Answers
Summary questions
1.1
1 (a)randomly arranged (b) close together,
randomly arranged (c) close together, only
vibrate
2Solid has a definite volume; gas has no
fixed volume / spreads out to fill container
completely
solid does not flow; gas can flow / spreads out
everywhere
solid can’t be compressed; gas can be
compressed
3(a) particles move faster, distance unchanged
(b)particles get closer together, speed
unchanged
1.2
1(a) boiling / evaporation (b) melting
(c) condensing
2energy absorbed; particles go from only
vibrating in place to sliding over each other
3volume decreases because particles slow down/
have less kinetic energy and hit the walls of the
syringe with less force.
4volume increases because while pressure
outside the syringe is lower than inside, gas
particles inside hit the walls and plunger of the
syringe with more force than those outside and
push the plunger outwards until atmospheric
pressure = pressure inside syringe
1.3
1 (a)liquid because 970°C is higher than the
melting point but lower than the boiling
point
(b)gas because 1500°C is higher than the
boiling point
2 (a)solid because –190°C is lower than the
melting point
(b)gas because –150°C is higher than the
boiling point
3 energy, melting, absorbed, forces, flat
2
4
Temperature
Unit 1 answers
Tm
Time
Tm = melting point
5energy absorbed is overcoming the forces
holding the particles close together instead of
raising the temperature
1.4
1 (a) mixture of solute in a solvent
(b)(compound) not containing water in its
structure
(c) does not dissolve in a (particular) solvent
(d) solution in water
2tap water contains impurities which may
interfere with the experiment
1000
= 32 g/dm3
3 4×
125
4 blue to pink
1.5
1particles; gases; random; different; mixed;
diffusion
2 (a)particles in solid break free from each
other / dissolve in water; particles
gradually spread out from higher to lower
concentration; by random movements /
collisions
(b)particles in liquid break free from each
other / particles escape into the air;
particles gradually spread out from
higher to lower concentration; by random
movements / collisions
3 methane; nitrogen; oxygen; carbon dioxide
End of unit summary questions
1 (a)the gradual spreading out and mixing up of
different particles by random movement
(b)the change of state from liquid to gas at
temperature below the boiling point
(c) the change of state from gas to liquid
2solid: particles close together; has a definite
shape; particles only vibrate (any 2); liquid:
particles close together; can flow but has
a definite surface; gas: particles move
everywhere; particles far apart
3 (a) energy absorbed
(b) energy released
4 anhydrous: does not contain water of
crystallisation
hydrated: contains water of crystallisation
solute: dissolves in a solvent
solvent: dissolves a solid, liquid or gas
5volume increases; particles have more energy
and hit each other and the walls of the
container with increased force ALLOW: particles
get further away from each other.
6 (a)More particles per unit volume put into the
balloon; greater frequency of collisions of
particles with the wall of the balloon; so the
pressure inside the balloon is greater than
atmospheric pressure and the balloon
expands.
(b)Particles in solids only vibrate / cannot
move and are close together. So they
cannot change positions.
(c)Particles in liquids are close together and
can be thought of as hard spheres (or other
shapes). So they cannot get any closer
together when pressure is applied.
Practice questions
1 C
2 D
3 (a)
[1]
[1]
(i)red colour in liquid around the crystal [1]
(ii)red colour spread (evenly) throughout
the water [1]
(b) (i)regularly arranged / arranged in rows
[1] motion: only vibrating ALLOW: do
not move [1]
(ii)irregularly arranged / randomly
arranged / no arrangement [1] motion:
sliding / slipping over each other
ALLOW: moving slowly (from place to
place) [1]
4 (a) (i) melting / fusion [1]
(ii) boiling / evaporation [1]
(iii) condensing [1]
(b)melting and boiling [1] attractive forces
between the particles overcome / reduced [1]
(c)arrangement: irregular / random / no
arrangement [1] motion: rapid / move
freely / move fast [1]
5 (a)volume decreases [1] particles pushed
closer together [1]
(b)volume increases [1] particles get further
apart / particles have more energy /
particles hit the side of the container with
greater force [1]
(c) (i) solute [1]
(ii) g/dm3 or mol/dm3 [1]
(d)arrangement: irregular ALLOW: random [1]
motion: slipping / sliding over each
other [1]
6 (a) (i)liquids absorb (thermal) energy from
surroundings, which overcomes forces
between particles [1] so that they can
spread apart, changing the substance
into a gas [1]
(ii)by diffusion [1] random movement of
particles when they collide [1]
(b)slightly closer to the HCl end / slightly
further from the methylamine end [1]
particle or molecule of methylamine is lighter
/ particle or molecule of HCl is heavier / HCl
has a higher molecular mass / methylamine
has a lower molecular mass. [1]
(c) (i)nearer the hydrogen chloride side /
further from the ammonia side [1]
(ii)ammonia has a lower molecular mass
than methylamine / methylamine
has a higher molecular mass than
ammonia. [1] rate of diffusion faster
for ammonia / rate of diffusion faster
the lower the molecular mass / mass
of molecule [1]
7 (a)increases pressure [1] particles pushed
closer together [1] increased frequency
3
of collisions of particles / greater force of
particles per unit area on wall of container [1]
(b)change of state is evaporation / boiling
[1] particles gain kinetic energy [1] forces
between water molecules / particles
overcome [1]
(c) (i)liquid cooling = C [1] gas changing to
liquid = B [1]
(ii)motion from rapid to less rapid /
decrease in speed / from freely moving
to restricted movement [1] separation
changes from far apart to close
together IGNORE: get closer [1]
(iii)In C energy of the particles is
decreasing as liquid cools [1]
In D energy is released / exothermic as
liquid changes to solid (solidification) [1]
In E energy of the particles is
decreasing as solid cools [1]
8 (a)one mark each for any two of: note level
of coloured water without the hydrogen
beaker present [1] place beaker of hydrogen
over porous pot [1] note how level of liquid
changes in each arm of the tube [1]
one mark for: coloured water higher in right
hand arm than left / coloured water goes
up [1]
(b)hydrogen diffuses faster than carbon
dioxide [1] hydrogen molecules move
into the pot [1] faster than carbon dioxide
moves out of the pot [1] pressure in pot
increases / number of molecules inside the
pot increases / concentration of molecules
inside the pot grows greater than in the
atmosphere [1] greater force on the coloured
water / greater frequency of collisions of the
molecules with surface of the water [1]
Unit 2 answers
Summary questions
2.1
1 (a)(top pan) balance (b) measuring cylinder
(c) burette/graduated pipette
4
2 (a)g or kg (b) dm3 or cm3 (c) °C or K or kelvin
3Use equipment with small scale divisions;
repeat measurements; use apparatus carefully
2.2
1 mixture; solubility; solvent; filter
2colour of the ink moves up the paper so you
don’t know which is the ink and which the
coloured substance/colour of ink moves up the
paper so base line no longer seen
3 valine>alanine>serine>lysine
2.3
1 sharp; solution; range; lower; pure
2S is impure; each separate spot is a different
substance
3melting point below 801°C ALLOW: down to 700°C;
boiling point above 1413°C ALLOW: up to 1500°C;
4 (a) impure (b) pure (c) impure (d) impure
2.4
1 (a)filtration ALLOW: decanting (b) evaporation
(c) crystallisation
2 solid; mixture; trapped; residue; filtrate
3heat gently to evaporate some of the solvent;
leave to crystallise; pick out/filter off the
crystals; dry crystals with filter paper
2.5
1distillation; volatile; lower; column
2 (a) fractional distillation
(b)dissolving (the copper(II) sulfate) then
filtration
(c) simple distillation
(d) chromatography
End of unit summary questions
1 (a)liquid which goes through the filter paper
during filtration
(b) solid left on the filter paper after filtration
(c)uniform mixture formed when a solute
dissolves in a solvent
(d)method of separating substances with
different boiling points from a mixture by
boiling the mixture and condensing the
vapours
2 (a) stopclock
(b) thermometer
(c)gas syringe ALLOW: upturned measuring
cylinder/burette over water
(d) volumetric (pipette)
3 volumetric flask: make up 500 cm3 accurately
measuring cylinder: measure out approx. 20 cm3
burette: measure out 18.5 cm3 accurately
beaker: to mix solutions
condenser: change a vapour to a liquid
4
Watch glass
(iii) B [1]
(iv) A [1]
6 (a) B [1] it has the lowest boiling point [1]
(b)A and D [1] They have boiling points which
are very close to each other [1]
(c)Fractional distillation depends on
difference in boiling points [1]
Mixture in flask heated and liquids
evaporate in order of volatility/lowest
boiling point first [1]
Rate of movement of vapours (gases) up
the column differs/the most volatile liquid
moves furthest up the column [1]
Chromatography paperVapours (gases) condense or change from
gas to liquid (in condenser) in order of
increasing volatility/decreasing boiling
Mixture
point of liquid [1]
Origin line
7 (a)boiling point of P is higher (than that of
(base line)
Solvent
pure ethanol) [1] P is slightly yellow [1]
ALLOW: filter paper in place of chromatography
(b)Any value between –116.9°C and –125°C [1]
paper
(c)Liquid [1] –20°C is higher than the melting
point but lower than the boiling point [1]
Practice questions
(d)evaporate some of the water (by heating)
1 C [1]
and leave to crystallise [1] pick out/filter off
2 D [1]
crystals [1] dry crystals on filter paper/dry
3 C [1]
crystals in drying oven [1] NOT: dry in oven
4 (a) (i)solute does not dissolve in a
8 (a)The origin line would move up the paper/
(particular) solvent ALLOW: does not
the colours in the ink would separate [1]
dissolve in water [1]
(b) 4 [1]
(ii)Add water and stir (to dissolve salt) [1]
(c)the amino acid furthest from the origin line
filter off the aqueous salt [1] evaporate
(the top mark) [1]
salt solution to dryness [1]
(d) 2.3/2.8 cm = 0.82 [1]
(b)Add mixture to water and shake (to dissolve
(e) use a different solvent [1]
salt)/Add mixture to hexane and shake (to
(f)spray chromatogram/spray paper [1] with
dissolve iodine) [1]
locating agent [1]
run off iodine solution / run off salt solution
(dependent on method used) [1]
Unit 3 answers
Evaporate iodine (solution) to dryness [1]
Summary questions
5 (a)see diagram above: solvent in bottom of
beaker and labelled [1]
3.1
chromatography paper labelled ALLOW:
1protons (neutrons); neutrons (protons);
filter paper [1]
nucleons; positive; no; electrons; shells; equal
origin line/base line above solvent level [1]
2 21
watch glass over beaker and labelled [1]
3 The number of positively charged protons = the
(b) (i) on the origin line/on the base line [1]
number of negatively charged electrons
(ii) C [1]
5
3.2
1 mass; neutrons; element; different; isotopes
2 (a) protons 92, electrons 92, neutrons 143
(b) protons 6, electrons 6, neutrons 8
(c) protons 26, electrons 26, neutrons 32
65
11
Cu (b) 127
3 (a) 29
53I (c)
5B
3.3
1 (a) 6
(b) 2
(c) 8
2 (a) 2,4 (b) 2,8,8,1 (c) 2,8,7 (d) 2,8,3
3.4
1 different; compound; ions; bonds
2 compounds have constant composition;
mixtures can be in any proportion; components
of compounds can’t be separated by physical
means; components of mixtures can be separated
by physical means; compounds have different
properties to the substances they are made from;
properties of mixtures are the average of the
properties of the substances they are made from;
ALLOW: energy change occurs when compound
made; usually no energy change or small energy
change when mixture made
3 compound; has completely different colour to
the substances it is made from
3.5
1conductors; thermal energy; ductile; opposite;
graphite; low
2 (a) e.g. sodium, potassium, gallium
(b) graphite
(c)e.g. conduct electricity / conduct thermal
energy / malleable / ductile / lustrous
(shiny) ALLOW: sonorous / high melting
point; high boiling point
End of unit summary questions
1 (a)
(b)
(c)
6
(i)in centre of atom / in nucleus
(ii) 1
(iii) +1
(i)in centre of atom / in nucleus
(ii) 1
(iii) 0
(i)outside the nucleus / far from the
nucleus
(ii) 1/1840 ALLOW:1/2000 or negligible
(iii) −1
2 O isotope p = 8; n = 8; e = 8
Pb isotope p = 82; n = 125; e = 82
H isotope p = 1; n = 0; e = 1
Cl isotope p = 17; n = 20; e = 17
3 (a)the number of protons plus neutrons in the
nucleus of an atom
(b)atoms with the same number of protons
but different numbers of neutrons
(c)substance containing two or more
elements or compounds not chemically
combined / bonded together
(d)substance containing two or more different
elements that are chemically combined /
bonded
4electrons = 18; protons = 19; neutrons = 22
5 isotopes: atoms of the same element with
different numbers of neutrons; element: a
substance containing only one type of atom;
compound: a substance containing two or more
different elements chemically bonded together;
proton: a positively charged particle in the nucleus
6 (a)metal (b) non-metal (c) non-metal
(d) non-metal (e) metal (f) non-metal
Practice questions
1
2
3
4
C [1]
D [1]
D [1]
(a) atoms which have the same number
of protons but different numbers of
neutrons [1]
(b) chlorine 35 = 18 [1] chlorine 37 = 20 [1]
(c)
Nucleus[1]
2,8,7 electrons[1]
3 electron shells[1]
(d) stable / unreactive electronic configuration [1]
5 (a)substance containing two or more
(different) elements bonded together/
chemically combined [1]
(b)1 mark each for any two of:
in compound iron and sulfur in fixed
7 (a) A has 2 electrons in its outer shell [1]
(b)B and E have the same number of electrons
in their outer shell / both have 6 electrons
in their outer shell [1]
(c) it has three shells of electrons [1]
(d) (i) atoms with the same number of protons
and different number of neutrons [1]
(ii) 17 [1]
8 (a) p = 16 [1] n = 20 [1] e = 18 [1]
(b)across a period number each successive
element has one more electron [1]
number of shells with electrons in them =
period number [1]
number of electrons in outer shell = group
number [1]
(c)they have the same electronic configuration [1]
(d)203 × 29.5 and 205 × 70.5 [1]
= 5 988.5 + 14 452.5 / idea of addition (allow
error carried forward) [1]
= 204.4 [1]
Unit 4 answers
Summary questions
4.1
1outer: transferred; chlorine; ions: noble; complete
2 (a) 2,8 (b) 2,8,8 (c) 2,8
3 (a)(a)
(b)
2+
2–
O 2– ion
Cl – Sion
2+ ion
+
××
××
×
××
××
××
× ×× ××
K+ ion
3+
Al 3+ ion
2–
× × ×
×
× ×× ××
S2+ ion
(b)
2–
× ×× ××
× ×× ×
× × ×
(c)
2–
(c)
2–
–
××
× ××
××
××
××
××
× ××
××
2+
+
×
××
3+
Al 3+ ion
× × ×
×
×
×××
× × ×
(a)
(b)
(b)(c)
Ca 2+ ion
Al 3+
K+ion
ion
× × ×
×
×
××
×
××
× ×
2–
O 2– ion
× ×
K+ ion
3+
×
× ×
Ca 2+ ion
×
× ×
proportions / in mixture iron and sulfur can
be in any proportion / no fixed amounts of
iron and sulfur [1]
in compound iron and sulfur can’t be
separated by physical means / in mixture
iron and sulfur can be separated by
physical means [1]
the properties of the compound are different
from those of the elements making it up /
the properties of a mixture are the average
of the elements which make it up [1]
(c) (i) 2,8,6 [1]
(ii) S has 6 electrons in its outer shell [1]
(iii) proton number [1]
(d)1 mark each for any 3 of:
iron conducts electricity / sulfur does not
conduct electricity [1]
iron conducts thermal energy / sulfur does
not conduct thermal energy [1]
iron is malleable / sulfur not malleable [1]
iron is ductile / sulfur not ductile [1]
iron is sonorous / sulfur not sonorous [1]
iron has high melting point (or boiling
point) / sulfur has low melting point (or
boiling point) [1]
iron dense / sulfur not dense [1]
ALLOW: iron is lustrous (or shiny) / sulfur
(powder) not shiny [1]
6 (a) (i)1 mark each for any three of:
conducts electricity / conducts thermal
energy / malleable / ductile / lustrous
(shiny) / sonorous ALLOW: high melting
point OR high boiling point [3]
(ii)1 mark each for any 2 of: low density [1]
(a) low melting point
(relatively)
[1] soft [1]
2+
(b)gas / has low boiling point [1] any other
reason for non-metals given in 5(d) [1]
(c)sodium chloride is white but neither iron
nor chlorine are white
[1]
Ca 2+ ion
O 2– ion
sodium chloride has a high melting point
but neither (c)
sodium nor chlorine
have high
+
melting points [1]
(d) (i) 2,8,1 [1]
(ii) 2,8,7 [1]
(e) 18 [1]
S2+ ion
7
4.2
1 molecules; electrons; noble; line; non-metal
(b)
(c)
(b)
2 (a) (a)
×
×
×
×
×
×
×
×
×
×
8
×
×
××
×
×
×
×
×
H
××
×
×
×
×
(b)
××
×
××
×
×
××
×
×
×
×
×
×
2molten: ions can move from place to place
when voltage applied.
solid: ions cannot move (from place to place)
3ionic; electrostatic; forces; lattice; melting; energy
H
S
F
F
Br
4.5
H
H 1covalent;
hexagons; strong; weak; melting; energy
(c)
2 layers of graphite slide over each other because
(c)
the forces are weak between the layers
S
Br
3 delocalised electrons move along the layers in
H
H
graphite but no delocalised electrons in diamond
4 one of: both have structure of linked
3 (a) 2
(b) 1
(c) 4
tetrahedrons / both have structure like linked
4.3
pyramids / both have structure of bent
1 two; triple; pairs; oxygen; nitrogen
hexagons;
(a)
(b)
(b)
2 (a)
both have atoms joined to 4 other atoms / C
H
and Si attached to 4 other atoms
H
Cl
one of: diamond has only 1 type of atom /
C
C
C
H
Cl
diamond is an element but SiO2 contains two
H
H
×
types of atom / is a compound
Cl
O-Si-O bond angle straight / 180°; all bonds in
diamond angular / less than 180° / less than 120°
4.6
(c)
(c)
1 positive; delocalised; attractions; melting;
P
H
H
malleable; layers
×
2 delocalised ‘sea’ of electrons move between the
H
positive ions when voltage applied
3 see right-hand part of Figure 4.6.2, p. 48; ions in
4.4
rows close to each other and labelled positive
1
ionic
simple molecular
ions / metal ions / metal cations ; electrons
shown as dots or e, labelled delocalised
+ and – ions
separate molecules
electrons or sea of electrons.
electrically charged
uncharged particles
particles
End of unit summary questions
solid at room
gas, liquid or solid at
1 simple molecular: has a low melting point and
temperature
room temperature
does not conduct electricity
ionic bonding
covalent bonding
giant ionic: has a high melting point and
high melting / boiling low melting / boiling
conducts electricity when it dissolves in water
point
point
giant covalent: has a high melting point but
conduct when molten do not conduct
doesn’t conduct electricity
or aqueous
metallic: solid conducts electricity
2 (a) ionic
(b) covalent
(c) covalent (d) ionic
3 pair; molecules; shares; electrons; shell; eight;
stable
4 A = simple molecular; B = ionic; C = simple
molecular; D = metal; E = ionic
5 (a) see Figure 4.1.1, p 38
(b) see Figure 4.2.4, p 41
(c) see Figure 4.2.1, p 40
6 (a)simple molecular
(b) ionic (c) giant covalent
Practice questions
1 B [1]
2 D [1]
3 (a)KCl has high melting (or boiling) point AND
methane has a low melting (or boiling)
point [1]
KCl conducts electricity when molten / KCl
conducts electricity in aqueous solution
AND methane does not conduct [1]
ALLOW: KCl soluble in water AND methane
is not (for 1 mark)
(b)Dot and cross diagram with 2.8.8
configuration AND + at top right [1]
(c)strong electrostatic force of attraction
[1] between positive and negative ions /
between oppositely charged ions [1]
(d) drawing as Figure 4.2.6, p 41 [1]
4 (a)Any 2 of: both contain only carbon atoms [1]
both covalently bonded [1]
both giant structures [1]
(b)1 mark each for any 2 of: diamond
tetrahedral shaped units / diamond bent
hexagonal units OR graphite hexagonal
(planar) units [1]
diamond atoms all joined as continuous
structure OR graphite layered structure [1]
C atoms in diamond joined to 4 others,
C atoms in graphite joined to 3 others [1]
(c) giant covalent [1]
(d)forces between the layers (of atoms) are
weak [1] layers can slide over each other [1]
(e) drilling / cutting [1] diamond is hard [1]
5 (a)drawing as Figure 4.3.5, p 43: two shared
electron pairs between the two C atoms [1]
rest of molecule correct [1]
(b) (i)weak forces of attraction between
molecules / intermolecular forces are
weak [1]
does not need much energy to
overcome these forces / only needs low
temperature to overcome these forces [1]
(ii)does not conduct electricity / thermal
energy [1]
(c)Ca ion as 2,8,8 [1], 2+ charge at top right [1];
Cl ion as 2,8,8 [1], single negative charge at
top right [1]
(d)regular arrangement of alternating positive
and negative ions [1]
(e)When solid, ions cannot move [1] when
molten, ions can move [1]
6 (a) (i)gas [1] small molecule with weak
intermolecular forces [1]
(ii)solid [1] giant covalent, lot of energy
needed / high temperature needed to
break large number of bonds [1]
(b)drawing as Figure 4.3.5, p. 43: two pairs of
bonding electrons between each C and O
[1], two pairs of non-bonding electrons on
each O atom [1]
(c) (i)both have structure of linked
tetrahedrons/ both have structure like
linked pyramids / both have structure
of bent hexagons [1]
both have atoms joined to 4 other
atoms / C and Si attached to 4 other
atoms [1]
ALLOW: both have giant covalent
structure
(ii)diamond has only 1 type of atom
/ diamond is an element but SiO2
contains two types of atom / is a
compound OR O-Si-O bond angle
straight / 180°; all bonds in diamond
angular / less than 180° / less than
120° [1]
(d) SiO2 [1]
(e)high melting / boiling point [1] lot of energy
needed / high temperature needed to
break large number of strong covalent
bonds [1]
does not conduct electricity [1] no mobile
electrons or ions [1]
9
7 (a)1 mark each for any three of: Zn conducts
electricity / thermal energy OR S does
not [1]
Zn high melting / boiling point OR S low
melting / boiling point [1]
Zn malleable / ductile OR S brittle [1]
Zn lustrous ALLOW: S dull [1]
Zn sonorous / S not sonorous [1]
(b)As right-hand drawing of Figure 4.6.1,
p. 48: ions in rows close to each other and
labelled positive ions / metal ions / metal
cations [1], electrons shown as dots or e
labelled delocalised electrons OR sea of
electrons [1]
(c) (i)layers of ions [1] slide over each
other [1]
(ii)delocalised sea of electrons [1] moves
when voltage applied [1]
(d)
×
×
××
Cl
××
××
××
Cl
××
××
S
one bonding pair between each Cl and S [1]
two lone pairs on S [1]
three lone pairs on both Cl atoms [1]
Unit 5 answers
Summary questions
5.1
1 (a)sodium bromide (b) magnesium oxide (c)
hydrogen iodide
2 (a) MgBr2
(b) KCl (c) BaO
(d) Mg3N2 (e) Ga2O3 (f) Na2S
3 (a) magnesium bromide
(b)aluminium iodide
(c) potassium sulfate
(d) strontium nitrate
5.2
(b) CO2
(c) C2H4
1 (a) N2
10
2 (a) potassium sulfate
(b) magnesium nitrate
(c) copper hydroxide
3 (a) CaCO3
(b) Mg(NO3)2
(c) NH4Cl
(d) Al2(SO4)3
5.3
1 (a)sodium + water → sodium hydroxide +
hydrogen
(b)magnesium + zinc sulfate → zinc +
magnesium sulfate
(c)copper oxide + sulfuric acid → copper
sulfate + water
2 (a) 2Na + Cl2 → 2NaCl
(b) Cl2 + H2 → 2HCl
(c) 2Na + O2 → Na2O2
3 (a) Cl2 + 2KBr → Br2 + 2KCl
(b) CuCl2 + 2NaOH → Cu(OH)2 + 2NaCl
(c) 2P + 3Cl2 → 2PCl3
5.4
1 (a) Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
(b) (l)
2 (a) Ag+(aq) + Br−(aq) → AgBr(s)
(b) Cu2+(aq) + 2OH−(aq) → Cu(OH)2(s)
(c) Br2(aq) + 2I−(aq) → I2(aq) + 2Br−(aq)
End of unit summary questions
1 (a)magnesium + chlorine → magnesium
chloride
(b) potassium + oxygen → potassium oxide
(c) sodium + bromine → sodium bromide
(d)carbon + oxygen → carbon dioxide
(ALLOW: carbon monoxide)
2 (a) NaCl (b) MgO (c) Al2O3
(d) CaCl2 (e) AlCl3
3 oxide = O2− ; hydrogen = H+; calcium = Ca2+;
chlorine = Cl2; chloride = Cl−; oxygen = O2
4 (a) 2Ca + O2 → 2CaO
(b) 2SO2 + O2 → 2SO3
(c) 2Na + Cl2 → 2NaCl
(d) C4H8 + 6O2 → 4CO2 + 4H2O
(e) Fe2O3 + 3CO → 2Fe + 3CO2
(f) 2PbO + C → 2Pb + CO2
5 (a)zinc + copper sulfate → zinc sulfate + copper
(b) iron + oxygen → iron oxide / iron(III) oxide
(c)ammonium chloride + sodium hydroxide
→ ammonia + sodium chloride + water
(d)copper nitrate + magnesium → copper +
magnesium nitrate
6 (a) Cl2(aq) + 2Br−(aq) → Br2(aq) + 2Cl−(aq)
(b) Fe2+(aq) + 2OH−(aq) → Fe(OH)2(s)
(c) Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g)
Practice questions
1 AGa2O3 [1]
2 D [1]
3 (a) NaCl, KBr, LiBr and KI [1]
(b) (i)ammonium bromide [1]
(ii) sodium sulfate [1]
(c)Cl2 + 2KBr → 2KCl + Br2 (1 for each
underlined and no other errors)
(d) (i) iodide [1]
(ii) oxide [1]
(iii) nitrate [1]
4 (a) (i) HCl [1]
(ii) H2SO4 [1]
(iii) MgSO4 [1]
(b) (i)Mg(s) + 2HNO3(aq) → Mg(NO3)2 (aq) +
H2(g) (1 for 2HNO3)
(ii)magnesium + nitric acid →
magnesium nitrate + hydrogen (1 for
each underlined)
(iii)(s) = solid AND (g) = gas [1] (aq) =
aqueous solution [1]
(c)2Mg + O2 → 2MgO (1 for correct formulae;
1 for correct balance)
5 (a)CaCO3 + 2HCl → CaCl2 + CO2 + H2O (1 mark
for each underlined)
(b)calcium carbonate → calcium oxide +
carbon dioxide [1]
(c) (i)CH4 + 2O2 → CO2 + 2H2O (1 mark for
correct formulae; 1 mark for balance)
(ii)formula showing number AND type of
different atoms in a molecule [1]
6 (a)N2(g) + 3H2(g) → 2NH3(g) (1 for correct
formulae; 1 for correct balance; 1 for correct
state symbols)
(b)NH3(g) + HCl(aq) → NH4Cl(aq) (1 for correct
formulae; 1 for correct state symbols)
(c)Cu2+ + 2OH− → Cu(OH)2 [2] (if 2 marks not
obtained, 1 mark for Cu2+ + OH−)
(d)2HNO3 + Ca(OH)2 → Ca(NO3)2 + 2H2O (1 mark
for correct formulae; 1 mark for balance)
7 (a)2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) (1 for
correct formulae; 1 for correct balance; 1 for
correct state symbols)
(b) (i)AgNO3(aq) + NaCl(aq) → AgCl(s) +
NaNO3(aq) (1 for correct formulae; 1
for correct state symbols)
(ii) Ag+(aq) + Cl−(aq) → AgCl(s) [1]
8 (a)the charge on the iron ion / oxidation
number [1]
(b)Fe2O3 + 2Al → 2Fe + Al2O3 (1 for correct
formulae; 1 for correct balance)
(c) (i) displayed [1]
(ii) CHO2 [1]
(iii)formula showing the simplest whole
number ratio of the different atoms or
ions in a compound [1]
Unit 6 answers
Summary questions
6.1
1 (a) 8
(b) 8
2 (a) 74.5 (b) 183
(c) 164
3 159.5 + (5 × 18) = 249.5
6.2
1 85.0 g
2 amount; molecules; mole
3 (a) 0.2 mol
(b) 0.3 mol
(c) 0.125 mol
6.3
1 56 g
2 4.2 g
3 35%
11
6.4
1 5.0 g
2 mol Mg = 0.1; mol of ethanoic acid = 0.1
The stoichiometry of the equation shows that
for 0.1 mol Mg we need 0.2 mol ethanoic acid.
But we have only 0.01 mol ethanoic acid, so Mg
is in excess and ethanoic acid is limiting.
6.5
1 volume; mole; room; pressure; all
2 (a) 6 dm3 (b) 1.4 g
3 1.67 × 10−3 mol CO2 = 1.67 × 10−3 mol CaCO3;
0.167 × 1/1.67 × 10−3 = Mr of 100
6.6
1 product; yield; masses; equation; theoretical
2 (a)11.50/23 = 0.5 mol Na; mol NaCl = 0.5 × 58.5
= 29.25 g NaCl
(b) 100 × 22.30/29.25 = 76.2%
3 100 × 24.5/26.5 = 92.5%
6.7
1 empirical; ratio; dividing; mass; atomic; lowest
2 CHO2 (O = 71.11%; moles = 2.223 C, 2.22 H and
4.444 O). Then divide by lowest number.
3 P4O10 (P2O5 = 142; 284/142 = 2; 2 × P2O5 = P4O10)
6.8
1 titration; acid; concentration; volume; moles;
stoichiometric
2 (a)0.2 × 25/1000 = 5 × 10−3 mol H2SO4(b) 0.01
mol NaOH (c) 0.01 × 1000/10 = 1.0 mol/dm3
NaOH
End of unit summary questions
1 (a) 102 (b) 142 (c) 342 (d) 208.5
2 Avogadro number: number of specified particles
in one mole of those particles
molar gas volume: volume occupied by one
mole of any gas
limiting reagent: reagent that is not in excess
relative molecular mass: sum of the relative
atomic masses
3 (a) 2.4/160 = 0.015 mol
(b) 9.6/160 = 0.06 mol
(c) 2 × 79.17/95 = 1.67 mol
12
4 (a)
(b)
(c)
5 (a)
(b)
(c)
6 (a)
(b)
(c)
7 (a)
(b)
(c)
(d)
7200 cm3
60 000 cm3
720 cm3
18.25 g
32.8 g
625.5 g
0.07 mol
0.04 mol
0.1 mol
1 mol/dm3
0.6 mol/dm3
0.05 mol/dm3
0.2 mol/dm3
Practice questions
1 D [1]
2 A [1]
3 (a) Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)
correct formulae [1]; correct balance [1];
correct state symbols [1]
(b) (i) 15.875 g / 15.9 g [1]
(ii) 280 g [1]
4 (a) 1 × 50/1000 = 0.05 mol [1]
(b)3.2/56 = 0.057 mol [1] stoichiometry is
1:1 so moles iron greater than moles
of acid [1]
(c)excess Fe = 0.007 mol [1] mass of Fe = 0.007 ×
56 = 0.392 g [1]
(d) 0.05 × 24 [1] = 1.2 dm3 / 1200 cm3 [1]
(e) Mr of FeSO4 = 152 [1]152 × 0.05 = 7.6 g [1]
(f) 7.22/ 7.6 [1] ×100 = 95% [1]
5 (a)Pipette a known volume of KOH into
flask [1]
Acid in burette [1]
Add indicator to flask [1]
Run acid into KOH until indicator changes
colour [1]
(b) (i)0.05 × 15/1000 = 7.5 × 10−4 mol
H2SO4 [1]
(ii)mol KOH = 1.5 × 10−3 [1]
concentration of KOH = 1.5 × 10−3 ×
1000
= 0.06 mol/dm3 [1]
25
(iii)
Mr of KOH = 56 so mass in 1 dm3 =
0.06 × 56 = 3.36 g [1] in 25 cm3 =
0.084 g [1]
6 (a) C = 0.96/12 H = 0.16/1 Cl = 2.84/35.5 OR
C = 0.08 mol H = 0.16 mol Cl = 0.08 mol [1]
divide each by 0.08 (C = 1 H = 2 Cl = 1) [1]
CH2Cl [1]
(b) empirical formula mass = 49.5 [1]
99/49.5 = 2 so C2H4Cl2 [1]
(c) (i)Cl = 8.1/71 = 0.114 AND CH4 = 1.6/16
= 0.1 [1]
methane is limiting [1]
(ii)(0.1 mol methane produces 0.1 mol
CH3Cl)
Mr of CH3Cl = 50.5 [1] yield = 0.1 × 50.5 =
5.05 / 5 g [1]
(iii)100 × 3.79/5.05 [1] × 100 = 75.05 /
75 % [1]
(d)5.05/50.5 = 0.1 mol [1] 0.1 × 24 = 2.4 dm3 /
2400 cm3 [1]
(e) 3 × 1/50.5 [1] × 100 = 5.9 / 6% [1]
7 (a) 5/100 = 0.05 mol CaCO3 [1] 0.1 mol HCl [1]
(b)volume = mol/ concentration OR volume =
0.1/ 0.5 [1]
0.2 dm3 / 200 cm3 [1]
(c) 35/100 = 0.35 mol [1] (= 0.35 mol CO2)
0.35 × 24 = 8.4 dm3 [1]
(d) (i) 1 mark each for any 2 of:
loss of material on filter paper / on
sides of beaker [1]
incomplete crystallisation / loss
during crystallisation [1]
side products formed [1]
ALLOW: reaction incomplete [1]
experimental yield
× 100 [1]
(ii) % yield =
theoretical yield
8 (a) (i) Mr of (NH4)NO3= 132 [1]
2 × 14
[1] × 100 = 21.2% [1]
132
(ii)(4 × 35) + (1 × 21.1) = 161.2 [1] 161.2/5 =
32.24 / 32.2% [1]
(b) (i)mol HNO3 = 2.0 × 15/1000 = 0.03 mol
[1] (= mol NH3)
concentration of NH3 = 0.03 × 1000/50
= 0.6 mol/dm3 [1]
(ii) 0.6 × 17 = 10.2 g/dm3 [1]
Unit 7 answers
Summary questions
7.1
1 resistance; electricity; thicker; thin; melt
2 substance which resists the flow of electricity
(or electric current) / substance which is a poor
conductor of electricity ALLOW: substance
which does not conduct electricity
3 (a)decomposition of an ionic compound
(when molten or aqueous) by passage of
electricity
(b)breakdown of a substance (into two or
more substances)
(c) positive electrode
7.2
1 (a) anode: fluorine; cathode: sodium
(b) anode: iodine; cathode: copper
(c) anode: bromine; cathode: zinc
2 (a)anode: red-brown gas (bromine); cathode:
silver-grey drops / coating (lead)
(b)anode: bubbles (oxygen); cathode: bubbles
(hydrogen)
(c)anode: bubbles of green gas (chlorine):
cathode: bubbles (hydrogen)
7.3
1 concentrated; hydrogen; ions; green; bubbles;
cathode
2 (a) anode: bromine; cathode: hydrogen
(b) anode: chlorine; cathode: hydrogen
(c)anode: oxygen / (small amount of) chlorine;
cathode: hydrogen
3 (a)anode: yellow-green gas (chlorine);
cathode: brown/ pink coating (copper)
(b)anode: yellow-green gas (chlorine);
cathode: bubbles (hydrogen)
(c)anode: brown solution (iodine); cathode:
bubbles (hydrogen)
13
7.4
1 positive; cathode; anode; hydrogen; gas; lose;
oxygen
2 (a) Pb2+ + 2e− → Pb (b) 2H+ + 2e− → H2
(c) 4OH− → O2 + 2H2O + 4e−
3 (a) anode: 2I− → I2 + 2e−
cathode: Zn2+ + 2e− → Zn
(b) anode: 4OH− → O2 + 2H2O + 4e−
cathode: 2H+ + 2e− → H2
7.5
1 electrolysed; anode; electrons; cathode; gain
2 (a) anode: 4OH− → O2 + 2H2O + 4e−
cathode: Cu2+ + 2e− → Cu
(b) anode: Cu → Cu2+ + 2e−
cathode: Cu2+ + 2e− → Cu
7.6
1 cathode; anode; electrolyte; solution; ions
2 Diagram as Figure 7.6.2 with metal anode
and object to be plated as cathode. Cathode
connected to negative pole of power pack and
anode connected to positive pole of power
pack. Electrolyte is solution containing ions of
the plating metal.
3 anode: Ni → Ni2+ + 2e−
cathode: Ni2+ + 2e−→ Ni
7.7
1 cryolite; lower; pure; energy; conductivity
2 carbon anode reacts with oxygen produced
by electrolysis to form carbon dioxide: carbon
dioxide is a gas so escapes to the atmosphere
3 4Al3+ + 12e− → 4Al
End of unit summary questions
1 (a)conductor
(b) conductor
(c) insulator
(d) insulator
(e) conductor
2 (a)decomposition of an ionic compound
(molten or aqueous) by an electric
current
14
(b)a rod which carries an electric current to or
from an electrolyte
(c)a particle which is formed by gain or loss
of one or more electrons from an atom or
group of atoms
(d)a substance which is a poor conductor of
electricity
(e)a substance, usually molten or in aqueous
solution, that decomposes on the passage
of an electric current
3 molten lead chloride: lead, chlorine
concentrated aqueous sodium chloride:
chlorine, hydrogen
dilute sulfuric acid: hydrogen, oxygen
molten aluminium oxide: aluminium, oxygen
4 Direct current
+
–
power supply
Anode
(positive electrode)
Cathode
(negative
electrode)
Electrodes
Electrolyte
Diagram with graphite/ platinum anode
and graphite/ platinum cathode. Cathode
connected to negative pole of power pack and
anode connected to positive pole of power
pack. Electrolyte is solution containing zinc
ions / soluble zinc salt.
5 (a)anode: yellow-green gas (chlorine);
cathode: shiny grey/silver solid (zinc)
(b)anode: red-brown gas/ vapour (bromine);
cathode: shiny silver liquid/ solid (potassium)
(c)anode: purple vapour (iodine)
cathode: shiny grey/ silver liquid solid (lead)
6 cathode; anode; electrolyte; tin; smaller;
electrons; attracted; gain; deposited
7 (a)cathode: bubbles of hydrogen released
since sodium more reactive (or less easily
discharged or gains electrons less readily)
than hydrogen / hydrogen lower in the
reactivity series than sodium (or more easily
discharged or gains electrons more readily)
anode: bubbles of oxygen released since
more water / more OH− ions than chloride
ion and reactivity similar (or ease of
discharge similar but much more water
present ) ALLOW: yellow-green chlorine
because more easily discharged than OH−
(b) cathode: 2H+ +2e− → H2
anode: 4O2− → O2 + 2H2O + 4e− / 2Cl− →
Cl2 + 2e−
Practice questions
1 D [1]
2 B [1]
3 (a) B [1]
(b) (i)bromine [1] red-brown gas ALLOW:
red-brown solution [1]
(ii) lead [1] grey/ silvery liquid/solid [1]
(c) → Br2 [1] Pb [1]
(d)a substance (either molten or in aqueous
solution) that decomposes on the passage
of an electric current [1]
(e) (i) graphite / platinum ALLOW: carbon [1]
(ii)electrical conductor [1] inert /
unreactive [1]
4 (a) D [1]
(b) (i)good electrical conductor [1] low
density [1]
(ii) to strengthen the cable [1]
5 (a)Ions can move in aqueous solution and
thus carry charge [1] ions cannot move in
solid [1]
(b) (i) iodine [1] (ii) hydrogen [1]
(c) (i) 2I− → I2 +2e− [1]
(ii) 2H+ +2e− → H2
(d)lithium more reactive (or less easily
discharged) / hydrogen lower in the
reactivity series than lithium (or more easily
discharged) [1]
Li+ gain electrons less readily than H+ / H+
gains electrons more readily than Li+ [1]
(e) any iodide of a reactive metal [1]
6 (a) (i)sodium more reactive (or less easily
discharged) / hydrogen lower in the
reactivity series than sodium (or more
easily discharged) [1]
Na+ gain electrons less readily than
H+ / H+ gains electrons more readily
than Na+ [1]
(ii)bromine less reactive (or more easily
discharged) / oxide higher in the
discharge series than bromide (or less
easily discharged) [1]
Br− loses electrons more readily than
O2− / O2− loses electrons less readily
than Br− [1]
(b) (i) 2H+ +2e− → H2 [1]
(ii) 2Br− → Br2 +2e− [1]
(c)anode AND oxidation is loss of
electrons [1]
(d)anode: oxygen ALLOW: chlorine and oxygen
[1] cathode: hydrogen [1]
7 (a) bauxite [1]
(b) 2Al2O3 → 4Al + 3O2 [1]
(c) (i)2O2− → O2 + 4e− [1]
(ii) Al3+ + 3e− → Al [1]
(d)to dissolve the aluminium oxide [1]
to lower the melting point of the
electrolyte [1]
(e)oxygen (from the electrolysis) reacts with
the carbon / graphite [1]
C + O2 → CO2 [1]
8 (a) (i)magnesium more reactive (or less
easily discharged) / hydrogen lower in
the reactivity series than magnesium
(or more easily discharged) [1]
Mg2+ gains electrons less readily than
H+ / H+ gains electrons more readily
than Mg2+ [1]
(ii) 2I− → I2 +2e− [1]
(b) (i)electrons move in external circuit
from the negative pole of the
battery to the cathode / towards the
positive pole of the battery from the
anode [1]
at the anode ions release electrons [1]
at the cathode ions gain electrons [1]
the ions in the electrolyte carry
the electrical charges (to either
electrode) [1]
15
(ii)oxidation at the anode because
electrons are lost [1]
reduction at cathode because
electrons are gained [1]
2
Energy
Unit 8 answers
Summary questions
Fe + S
Energy
CaO + CO2
∆H = +572 kJ/mol
CaCO3
Reaction pathway
8.1
1 (a)physical change: no new substance formed;
ALLOW: change is always reversible
chemical change: new substance formed;
ALLOW: change not always reversible
(b)physical change: any two of: melting,
condensing, freezing, boiling etc. ALLOW:
dissolving
chemical change: any two chemical
reactions
2 absorbs; surroundings; decreases; exothermic;
reaction; increases
3 (a)energy associated with movement of
particles (vibration/rotation/translation)
(b)surroundings: anything other than the
reactants or products of the chemical
reaction, e.g. the beaker, the air
8.2
1 minimum energy that colliding particles must
have in order to react
2
–100 kJ/mol
FeS
Reaction pathway
Ea may be included
3 reactants: products; downwards; negative;
activation; upwards; break
8.3
1 energy needed to break bonds in ethane and
oxygen is less than energy released when new
bonds formed
16
Ea
3 breaking bonds: 436 + 158 = + 594 kJ forming
bonds = 2 × 568 = –1136 kJ
energy change = –542 kJ
8.4
1 transport; exothermic; transferred; coal; acid;
global
2 (a) ethane + oxygen → carbon dioxide + water
(b) carbon + oxygen → carbon dioxide
1
3 2C4H10 + 13O2 → 8CO2 + 10H2O or C4H10 + 6
2
O2 → 4CO2 + 5H2O
8.5
1 oxygen; electricity; water; pollutant
2positive electrode O2 + 4H+ + 4e− → 2H2O
negative electrode 2H2 → 4H+ + 4e−
3 no pollutants formed / only water formed; more
efficient; more energy per gram of fuel used
End of unit summary questions
1 (a) exothermic (b) endothermic
(c) endothermic (d) exothermic
2 reaction; reactants; products; gain;
surroundings; decreases
3 Bond breaking is endothermic;
Bond making is exothermic;
Reduction takes place at a cathode;
A fuel cell is a source of electrical energy;
Methane is a hydrocarbon
Practice questions
1 B
2 D
3 A
4 (a) exothermic [1]
(b)take temperature of hydrochloric acid and
potassium hydroxide separately [1]
add the two reactants together [1]
take (maximum) temperature after addition
[1] (temperature increases)
(c)reactants on left and products on right in
correct place [1]
−20 kJ in middle of downward arrow /
energy released [1]
x-axis labelled reaction pathway [1]
(d) 40 kJ [1]
5 (a) (i)sodium hydroxide or calcium chloride [1]
(ii) potassium nitrate [1]
(b) endothermic [1]
(c) sodium hydroxide [1]
(d) (i)10°C change / final temp 28°C [1] the
same amount of energy is spread
through twice the volume [1]
(ii) 40°C change / final temp 58°C [1]
6 (a) hydrocarbon [1]
(b)methane + oxygen → carbon dioxide +
water (1 mark for correct reactants with
arrow and + signs; 1 mark for correct
products)
(c) (i)combustion when oxygen is not in
excess [1]
(ii) carbon monoxide [1]
(d)C3H8 + 5O2 → 3CO2 + 4H2O (1 mark for 3 and
1 mark for 4 in correct place)
7 (a)reaction which transfers energy to the
surroundings ALLOW: reaction which gives
out energy / reaction which releases energy
(b)bond breaking is endothermic and bond
making is exothermic [1]
more energy released than absorbed [1]
(c)Diagram similar to Fig 8.2.4 in text:
axes labelled correctly [1]
reactants above products and reactants to
the left of the products with energy
‘hump’ [1]
Ea labelled correctly shown as upward
arrow [1]
∆H labelled correctly and shown as
downward arrow [1]
(d) (i)(4 × 413) + (2 × 498) = + 2648 kJ [2] (If
2 marks not scored, 1 mark for either
(4 × 413) or (2 × 498)
(ii)(2 × 805) + (4 × 464) = − 3466 kJ [2] (If
2 marks not scored 1 mark for either
(2 × 805) or (4 × 464)
(iii)+ 2648 – 3466 = −818 kJ (1 for – sign
and unit, 1 for correct numerical
answer)
8 (a)hydrogen reacts with oxygen to form water,
which is not a pollutant [1] combustion of
gasoline produces carbon dioxide [1] which
contributes to global warming [1] ALLOW:
gasoline produces CO / C [1] with suitable
environmental issue [1]
(b) bonds broken: (2 × 436) + 498 = + 1370 kJ [1]
bonds formed 4 × 464 = − 1856 kJ [1]
energy released = − 486 kJ [1]
(c)(i)2H2 + 4OH− → 4H2O + 4e− [2] (1 mark
for incorrect balance of electrons or
electrons on wrong side)
(ii)O2 + 2H2O + 4e− → 4OH− [2] (1 mark
for incorrect balance of electrons or
electrons on wrong side)
(iii)electrons released at negative
electrode [1]
electrons accepted by oxygen and
water at positive electrode [1]
idea of electrons moving in external
circuit from where they are at higher
concentration to where they are at
lower concentration [1]
Unit 9 answers
Summary questions
9.1
1 rate; decrease; mixture; mass
2 similar to graph in Figure 9.1.2 p108
3 iron rusting, cement setting, firework exploding
4 The sulfur dioxide will dissolve in water so will
not collect at the top of the measuring cylinder
17
Mass
9.5
1 rate; increases; concentration
2 a & b – see graph
b
a
Time
3 collision; concentrated; unit; collide; frequently
4 Fewer reactant particles per unit volume as time
increases; collision frequency decreases
9.6
1 time; slower; rate
2
Mass
Time
9.2
1 mass loss of mixture / increase in volume of
hydrogen / change in pH / change in electrical
conductivity / increase in pressure of hydrogen
2 constant; dependent; measure; variable
3 (a)any two of: distance of flame from
calorimeter/ height of flame/ amount of
water in calorimeter / same calorimeter /
same temperature of water at start / same
external temperature
(b)thermometer not accurate / thermometer
on bottom of can / energy lost from can to
air / energy lost to walls of can / draughts
of air / flame flickering or not constant
height / evaporation of alcohol from burner
(before or after weighing) / carbon deposit
on calorimeter from flame prevents heat
getting to calorimeter
9.3
1
b
c
a
Temperature
Time
2 calcium carbonate; the reaction has finished so
all the hydrochloric acid is used up/ there is still
calcium carbonate present
3 fast; slows; stops
9.4
1 increases; rate; unchanged; again
2 very large surface area makes it extremely
reactive (because many particles exposed to air)
– reactive enough to cause explosion
3 Beads have larger surface area so greater
number of particles exposed for collision with
gas molecules
4 Lowers the activation energy so there is a
greater proportion of successful collisions
18
3 faster; kinetic; energy; more; activation;
effective; increases
End of unit summary questions
1a purple solution changes to a colourless solution:
measure the light transmitted through a solution
hydrogen is released during a reaction: measure
the volume of gas produced
two solutions react slowly to form a precipitate:
see how long it takes for a mark under the flask
to disappear
there are more ions in solution in the reactants
than in the products: measure change in
electrical conductivity
2 (a)increase in concentration or amount
of product per unit time or decrease in
concentration / amount of reactant per
unit time
3
4
5
6
7
8
(b)substance which increases rate of reaction
without itself changing
(c) (idea of) rise over run of graph
Graph as in Fig 9.1.2 on page 108
(a) increases
(b) decreases
(a) rate decreases
(b) rate decreases
increase in pressure increases rate. The particles
are pushed closer together at higher pressure,
so the concentration increases / number of
particles per unit volume increases. Greater
frequency of (effective) collisions.
(a)The reactant which is not in excess and is
used up first
(b)The minimum energy needed for colliding
particles to react
(c)the number of collisions per unit time
At higher temperatures particles vibrate more /
move more / have greater kinetic energy. More
particles have the activation energy to react
(with other molecules / with the air)
Practice questions
1 D [1]
2 (a)all points plotted correctly [2] (1 mark if one
point incorrectly plotted)
smooth curve through the points [1]
(b)curve to the left of the one already plotted
[1] final volume the same or only slightly
above the line already plotted [1]
(c)gradient of graph much lower ALLOW:
nothing happens [1] because catalyst
increases rate of reaction [1]
3 (a)Substance that speeds up reaction /
substance that increases rate of reaction [1]
(b) copper(II)sulfate [1]
(c)1 mark each for any 3 of: amount of
catalyst; concentration of HCl; mass of zinc;
temperature; size of zinc particles
(d) sodium chloride AND sodium sulfate [1]
4 (a) line 1 [1]
(b)A [1] because the gradient is greatest /
steepest [1]
(c)gas syringe or measuring cylinder full of
water in a trough of water [1] connecting
tubes to flask [1] apparatus airtight [1]
(d)use smaller pieces of calcium carbonate /
calcium carbonate powder [1] increasing
the temperature [1]
5 (a)gas syringe [1] volume of gas increases as
the reaction proceeds [1] decrease in mass
of reaction mixture [1] hydrogen lost as
reaction proceeds [1]
(ALLOW: change in pH [1] because acid
used up [1] OR electrical conductivity [1]
because fewer hydrogen ions as reaction
proceeds [1])
(b)idea of measuring the volume / mass etc [1]
at particular times / at intervals of time [1]
draw tangent to graph at particular point
[1] calculate gradient from the tangent (as
rise/run) [1]
(c) (i)increased rate [1] more particles per
unit volume [1] greater frequency of
collisions of particles [1]
(ii)decreases rate [1] particles move
slower / particles have less kinetic
energy [1] fewer particles have energy
greater than activation energy [1]
(iii)increases rate [1] greater surface
area of magnesium powder [1] more
magnesium particles exposed to HCl for
reaction in the same amount of time [1]
6 (a)mass on y axis and time on x axis [1] graph is
concave downwards curve [1] (see Fig 9.1.2
on page 108)
(b)the steeper the gradient, the greater the
rate [1] the gradient of the graph is steepest
at the start / the gradient of the graph is
least steep near the end / the gradient gets
less steep with time [1]
(c)As time proceeds there are fewer reactant
particles [1] per unit volume [1] so collision
frequency decreases [1]
(d) (i)2.0 × 30/ 1000 = 0.06 mol acid [1] 4/100
= 0.04 mol CaCO3 [1]
(ii)hydrochloric acid because
0.04 × 2 = 0.08 moles required for every
0.04 mol calcium carbonate [2]
(if 2 marks not scored, 1 mark for
idea of meaning of limiting reactant
e.g. calcium carbonate because it is
present in smaller number of moles)
19
(e) (i)temperature on x axis and time on
y axis [1] points plotted correctly
showing downward concave direction
[1] smooth line through the points [1]
(ii) 4 seconds [1]
7 (a)large pieces of zinc have smaller total
surface area [1] fewer zinc particles
exposed if smaller surface area [1] fewer
collisions per second / lower collision
frequency [1]
(b)fewer particles per unit volume [1] collision
frequency lower [1]
(c)(reaction 1 mol:1 mol) moles zinc = 6.5/65 =
0.1 mol [1] mol acid at higher concentration
= 1.5 × 50/1000 = 0.075 mol [1]
(d)Zn(s) + 2H+(aq) → Zn2+(aq) + H2(g) equation
correct [1] state symbols correct [1]
Unit 10 answers
Summary questions
10.1
1 crystallisation; white; anhydrous; chloride; pink;
reversible
2 closed system / concentrations of reactants and
products do not change at equilibrium / rates of
forward and backward reactions the same
3 (a)The extent to which reactants or products
predominate / how far the reaction is to the
left or right
(b) matter cannot escape from the container
10.2
1 equilibrium; concentration; right; disturbed;
products
2 (a)position of equilibrium moves further to the
right as there are fewer moles of gas on
the right
(b)position of equilibrium moves further to the
left to increase the concentration of CO
(c)position of equilibrium moves to the left.
For an endothermic forward reaction,
when the temperature is decreased, the
equilibrium shifts in favour of the backward
exothermic reaction.
20
10.3
1 sulfur; oxidised; reduced; loses
2 (a) Na oxidised, O2 reduced
(b) C oxidised, PbO reduced
(c) CO oxidised; CuO reduced
3 Ca2+ + 2e– → Ca is reduction
2Cl– → Cl2 + 2e– is oxidation
10.4
1 number; redox; increase; oxidation; decrease;
species
2 (a) +3
(b) +1
(c) +2
(d) –2
(e) +6
3 magnesium is oxidised because it loses
electrons / increases in ox. no.
iron ions reduced because Fe2+ gains electrons /
Fe2+ decreases in ox. no.
10.5
(b) O2
(c) Zn2+
1 (a) Fe2O3
2 (a) CO
(b) I−
(c) Li
–
3 purple colour (of MnO4 ions) to brown
colour (of I2); oxidising agent is potassium
manganate(VII)/ MnO4– ; reducing agent is
potassium iodide / I–
End of unit summary questions
1 oxidation: loss of hydrogen or addition of oxygen
reversible reaction: a reaction that can go in the
forward or backward direction
reduction: removal of oxygen or addition of
hydrogen
anhydrous: without water
2 (a) reduced
(b) oxidised
(c) oxidised
(d) reduced
3 (a)potassium manganate(VII) / potassium
permanganate; purple to colourless
(b) potassium iodide; colourless to brown
4 closed system / concentrations of reactants and
products do not change at equilibrium / rates of
forward and backward reactions the same
5 (a)more CaCO3 formed / more reactant
formed / position of equilibrium moves to
the left
(b)more CaCO3 formed / more reactant
formed / position of equilibrium moves to
the left
(c)more CaO and CO2 formed / more products
formed / position of equilibrium moves to
the right
(d)more CaCO3 formed / more reactant
formed / position of equilibrium moves to
the left
6 cobalt(II) chloride turns from red/pink to blue
because the water of crystallisation is removed
on heating
7 (a) reduction
(b) oxidation
(c) reduction
(b) CuSO4 / Cu2+ ions (c) MnO4–
8 (a) Cl2
Practice questions
1 A [1]
2 A [1]
3 (a) (i) add water [1]
(ii) CuSO4 + 5H2O → CuSO4.5H2O [1]
(b)hydrated [1] crystallisation [1] anhydrous [1]
(c) (i) Cu [1]
(ii)removal of oxygen (from a compound)
/ gain of electrons / decrease in
oxidation number [1]
(d)Fe2O3 [1] it loses oxygen [1]
4 (a)fewer particles of reactant to collide per
unit volume (as time goes on) [1] frequency
of collisions decreases [1]
(b)more particles of products per unit volume
[1] frequency of collisions increases [1]
(c)rate of forward reaction equals rate of
backward reaction [1]
(d)more product formed / more HI formed /
equilibrium shifts further to the right [1]
to reduce the amount of iodine added /
because increased concentration of iodine
increases rate of forward reaction [1]
(e)equal volume of gases on each side of the
equation / equal number of moles of gas
on each side of the equation [1]
(f)position of equilibrium moves to the left /
more reactants formed [1] The forward
reaction is exothermic / the backward
reaction is endothermic / the reaction
moves in the direction of absorbing heat [1]
5 (a)(i) 0 [1] (ii) –1 [1]
(iii) c hlorine [1] it increases the oxidation
number of iodide ions (from –1 to 0) [1]
(b) Cl2 + 2I– → 2Cl– + I2 [2]
(1 mark for correct species, 1 mark for
correct balance)
(c) Cl2 + 2e– → 2Cl– [1] 2I– → I2 + 2e– [1]
(d) (i)equilibrium reaction ALLOW: reversible
reaction [1]
(ii)more brown liquid formed / less
yellow colour [1] equilibrium shifts
further to the left [1]
as chlorine is no longer being added
and pushing the equilibrium to the
right / forming more product
(iii)position of equilibrium moves to
left / more reactants formed [1] for
decrease in pressure reaction goes in
direction of greater number of moles
of gas [1]
6 (a)nitrogen is being oxidised and oxygen
reduced [1] both oxidation and reduction
are occurring together [1] N2 is the reducing
agent [1]
(b)equilibrium shifts to the right [1] in the
direction of absorption of heat energy [1]
(c) (i)S is being oxidised [1] since ox. no. of
S increases from 0 to +6 [1] nitric acid
is oxidising agent because it oxidises
S / nitric acid is the oxidising agent
because the N in nitric acid is being
reduced [1]
(ii)
+5 [1]
(iii)S loses electrons [1] N in HNO3 gains
electrons [1]
7 (a)1 mark each for any two of:
concentration of reactants and products
remains constant / rate of forward reaction
= rate of reverse reaction / reaction is
reversible
(b) (i)position of equilibrium moves to the
left [1] to overcome/ reduce the effect
of decreasing the concentration of
chlorine [1]
21
(ii)position of equilibrium moves to the
right [1] there are fewer moles of gas /
lower volume of gas on the product
side OR there is 1 mol of gas on the left
but none on the right [1]
(c) (i) +1 [1]
(ii) –1 [1]
Unit 11 answers
Summary questions
11.1
1 scale; alkaline; acidic; high; neither; neutral;
seven; universal
2 (a) acidic (orange)
(b) alkaline (blue / purple)
(c) neutral (green)
(d) alkaline (blue-green ALLOW: blue)
3 Add drops of each solution to universal
indicator paper. Observe the colour. Match the
colour with the colour on the universal indicator
colour chart. Sodium hydroxide gives blue and
ethanoic acid gives orange / red.
11.2
1 dissolves; hydrogen; salt; oxides; hydroxides;
water
2 (a)zinc sulfate
(b)calcium chloride
(c)magnesium nitrate
3 (a)magnesium + nitric acid → magnesium
nitrate + hydrogen
(b)copper(II) carbonate + hydrochloric
acid → copper(II) chloride + water +
carbon dioxide
(c)sodium hydroxide + sulfuric acid → sodium
sulfate + water
11.3
1 soluble; hydroxide; ammonia; acids; salt
2 (a)ammonium sulfate + potassium
hydroxide → ammonia + potassium sulfate
+ water
(b)calcium oxide + hydrochloric acid →
calcium chloride + water
22
(c)magnesium hydroxide + nitric acid →
magnesium nitrate + water
3 (a)H2SO4 + 2KOH → K2SO4 + 2H2O
(b)Ca(OH)2 + 2HCl → CaCl2 + 2H2O
11.4
1 dissolves; ions; hydrogen; proton; base
2 an acid which is incompletely dissociated in
aqueous solution
3 pH of strong acid is lower / strong acid reacts
faster with magnesium
11.5
1 titration; volumetric; indicator; burette; colour;
end
2 (a)red (or pink); yellow
(b)colourless; blue
(c)blue; red/ pink
11.6
1 acidic; alkalis; salt; react; litmus; metals
2 add water: it reacts (ALLOW: dissolves) to form an
alkaline solution / solution turns red litmus blue
OR add acid: reacts with fizzing / bubbles formed
3 (a)ZnO + 2HCl → ZnCl2 + H2O
(b)Al2O3 + 2KOH → 2KAlO2 + H2O
End of unit summary questions
1 acid + carbonate: salt + water + carbon dioxide
acid + hydroxide: salt + water
acid + metal: salt + hydrogen
ammonium salt + alkali: salt + ammonia + water
2 (a)zinc + hydrochloric acid → zinc chloride +
hydrogen
(b)sulfuric acid + magnesium oxide →
magnesium sulfate + water
(c)calcium carbonate + nitric acid → calcium
nitrate + carbon dioxide + water
(d)ammonium sulfate + potassium hydroxide
→ potassium sulfate + ammonia + water
3 (a)substance which is a different colour in acid
and alkali and changes colour at the endpoint of a titration.
(b) (i) c olourless
(ii)red / pink
4 vinegar: pH 4.5, weakly acidic
dishwasher powder: pH 12, strongly alkaline
soap: pH 7.5, weakly alkaline
distilled water: pH 7, neutral
concentrated hydrochloric acid: pH 0, strongly
acidic
5 (a)basic (b) basic
(c)acidic (d) acidic
6 (a)Na2CO3 + 2HNO3 → 2NaNO3 + CO2 + H2O
(b)Mg + 2HCl → MgCl2 + H2
Practice questions
1 C [1]
2 D [1]
3 (a)substance containing hydrogen ions [1]
(b)sulfuric acid [1]
(c)H2SO4 [1] H2O [1]
(d)basic oxide [1] magnesium is a metal [1]
(e) (i)sulfuric acid + magnesium carbonate /
sulfuric acid + magnesium [1]
(ii)sulfuric acid + magnesium carbonate →
magnesium sulfate + carbon dioxide + water
(1 mark for correct reactants; 1 mark for
correct products)
OR
sulfuric acid + magnesium → magnesium
sulfate + hydrogen
(1 mark for correct reactants; 1 mark for correct
products)
4 (a)pH 10 [1]
(b)turns it blue [1]
(c)ammonium sulfate + sodium hydroxide →
ammonia + sodium sulfate + water
(1 mark for ammonia; 1 mark for sodium
sulfate + water)
(d) (i)NH3 [1] HCl [1]
(ii)ammonium chloride [1]
(e)yellow to red ALLOW: orange to red
5 (a) (i)blue [1] to colourless [1]
(ii)Add drops of HCl to universal indicator
paper. [1] Match the colour with the
colour on the universal indicator
colour chart [1]
(b) (i)magnesium + hydrochloric acid →
magnesium chloride [1] + hydrogen [1]
(ii)magnesium chloride [1]
(c)2(HCl) [1] CO2 [1] H2O [1]
(d)acidic oxide [1]
(e)pH (of potassium hydroxide) above pH 7
(maximum quoted = pH 14) / pH alkaline [1]
pH ends below pH 7 [1] If 2 marks not
scored, allow 1 mark for pH decreases.
6 (a)Add drops of ethanoic acid to universal
indicator paper. [1] Match the colour with
the colour on the universal indicator colour
chart. [1] Colour is yellow / orange / pH is
quoted value between > 3 and < 7 [1]
(b)Compare reactivity with same
concentration of a strong acid [1] Add
metal / metal oxide / metal carbonate [1]
solid decreases in size / solid disappears
more slowly than with strong acid (not
solid dissolves) [1] bubbles / effervescence
less than with strong acid [1]
(c)2CH3COOH + Mg → (CH3COO)2Mg + H2
(1 mark for correct formulae; 1 mark for
correct balance)
(d)proton transferred / lost from COOH group
of ethanoic acid [1] OH of KOH gains this
proton [1]
(e)base which is completely dissociated in
aqueous solution [1]
7 (a)CaO + 2HCl → CaCl2 + H2O (1 mark for
correct reactants and products, 1 mark for
correct balance)
(b)proton acceptor [1]
(c)CH3COOH ⇋ CH3COO− + H+ correct
formulae [1] rest of equation correct [1]
(d)O2− + 2H+ → H2O [1] IF 2 marks not scored,
1 mark for O2−
(e) (i)amphoteric oxide [1]
(ii)2NaOH(aq) (on left) [1] H2O (on
right) [1]
8 (a)Base that dissociates partially in aqueous
solution [1]
(b)2NH3 + H2SO4 → (NH4)2SO4 [2] IF 2 marks not
scored, 1 mark for (NH4)2SO4
23
(c)H+ ion from NH4+ donated [1] to OH− ion [1]
OR H+ ion lost from NH4+ [1] OH− ion accepts
H+ ion [1]
(d)NH3 accepts proton from water so base [1]
H2O donates proton to NH3 so acid NH4+
donates proton to OH– so acid [1] OH–
accepts proton from NH4+ so base [1]
Unit 12 answers
Summary questions
12.1
1 insoluble; neutralised; oxide; limiting; filter;
filtrate
2 (a)iron(III) oxide + hydrochloric acid →
iron(III) chloride + water
(b)magnesium + sulfuric acid → magnesium
sulfate + hydrogen
3 Add zinc oxide to hydrochloric acid until the
oxide is in excess then warm.
Filter off the excess zinc oxide then
evaporate the water from the filtrate until the
crystallisation point is reached. Leave the salt to
crystallise at room temperature.
Filter off the crystals then wash them and dry
them between sheets of filter paper.
12.2
1 soluble; alkali; burette; indicator; repeated
2 (a)aqueous ammonia + hydrochloric acid
(b)sodium hydroxide + hydrochloric acid
(c)aqueous ammonia + nitric acid
3 (a)sodium nitrate
(b)ammonium sulfate
(c)lithium chloride
12.3
1 b/ silver bromide; d/ barium sulfate; e/ lead
iodide
2 insoluble; precipitation; ion; attracted; lattice;
spectator
3 (a)Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) +
2KNO3(aq)
(b)FeCl2(aq) + 2NaOH(aq) → Fe(OH)2(s) +
2NaCl(aq)
24
12.4
1 collecting; heavier; displacement; insoluble;
water
2 (a)ammonia turns damp red litmus paper
blue
(b)chlorine bleaches litmus paper / universal
indicator paper
3 test for oxygen uses glowing splint, test for
hydrogen uses lighted splint;
results: oxygen relights (glowing) splint,
hydrogen pops / explodes
12.5
1 cations; hydroxide; ammonia; precipitate;
colour; white; zinc
2 (a)red-brown (b) white (c) blue
3 add a few drops of sodium hydroxide: both
calcium ions and zinc ions produce white
precipitate
add excess sodium hydroxide: precipitate
with calcium ions is not soluble in excess but
precipitate with zinc ions is soluble in excess to
form a colourless solution
OR
add a few drops of aqueous ammonia: no
precipitate or slight white precipitate with
calcium ions but white precipitate with
zinc ions.
12.6
1 (a)iodide (b) sulfate
2 (a)Add aluminium and sodium hydroxide then
warm. Gas produced turns damp red litmus
blue
(b)Add hydrochloric acid. Gas produced turns
limewater milky / white precipitate
(c)Add nitric acid then aqueous silver nitrate.
Cream precipitate.
3 copper(II) iodide
End of unit summary questions
1 iron(II) ions: sodium hydroxide
iodide ions: silver nitrate
sulfate ions: acidified barium chloride
carbon dioxide: limewater
nitrate ions: warm with aluminium powder and
sodium hydroxide
2 salt; excess; sulfuric; filtered; filtrate;
evaporating; water; crystallise
3 (a)test for oxygen uses glowing splint, test for
hydrogen uses lighted splint;
(b)oxygen relights (glowing) splint, hydrogen
pops / explodes
4 Put a known volume of sodium hydroxide in a
flask → add a suitable acid-base indicator →
add acid from the burette until the indicator just
changes colour → record the volume of acid
added → repeat the titration exactly as before
but without the indicator until the volume of
acid you recorded before has been added →
evaporate solution to point of crystallisation →
leave to form crystals → wash crystals → dry
crystals with filter paper
5(i)add iron metal to hydrochloric acid;
add iron(II) oxide to hydrochloric acid
and warm; add iron(II) carbonate to
hydrochloric acid
(ii) iron; iron(II) oxide; iron(II) carbonate
6 (a)insoluble (b)soluble
(c)insoluble (d)soluble
(e)insoluble
(f) soluble
(g) soluble (h) insoluble
7 (a) iii (b) i (c) iii (d) ii
Practice Questions
1
2
3
4
B [1]
D [1]
D [1]
(a)evaporate to point of crystallisation / heat to
form saturated solution [1] leave to crystallise
[1] wash crystals with cold solvent [1] dry
with filter paper / dry in drying oven [1]
(b)to make sure that all the sulfuric acid had
reacted [1]
(c)(add hydrochloric / nitric acid) add (aqueous)
barium chloride / nitrate [1] white precipitate [1]
5 (a)turns it red [1]
(b)pass through limewater [1] turns cloudy /
milky / white precipitate [1]
(c)white precipitate [1] on addition of
(aqueous) sodium hydroxide [1] which is
insoluble in excess sodium hydroxide [1].
On addition of ammonia no precipitate [1]
(d)One mark each for any 2 of: L is calcium
carbonate [1] M is ethanoic acid [1] reaction
of acid with carbonate produces CO2 [1]
molecular formula of M consistent with
CH3COOH for ethanoic acid. [1]
(e)sodium [1] sulfite [1]
6 (a)hydrochloric acid [1]
(b)Apparatus as in Fig 12.2.2 flask under
burette [1] flask labelled [1] burette
labelled [1]
(c)add indicator to flask [1] potassium
hydroxide in flask and hydrochloric acid in
burette [1] add acid from burette (to alkali)
until indicator changes colour [1]
(d)record volume of acid added when
indicator changes colour [1] repeat
experiment without indicator [1] using
same volume and concentration of both
alkali and acid [1]
(e)dissolve crystals in water / add dilute nitric
acid to crystals [1] add aqueous silver
nitrate [1] white precipitate (if chloride ions
present) [1]
7 (a)lead nitrate [1] any soluble iodide, e.g.
potassium iodide [1]
(b)Pb2+(aq) + 2I−(aq) → PbI2(s)
correct formulae [1], correct balance [1],
correct state symbols [1] (dependent on
correct formulae)
(c)Add the two aqueous solutions together
[1] filter off the solid / precipitate [1] wash
precipitate with cold water [1] dry crystals
with filter paper / dry in drying oven [1]
(d)add dilute nitric acid and aqueous silver
nitrate [1] (light) yellow precipitate [1]
(e)(i)Ba2+ (aq) + SO42− (aq) → BaSO4 (s) [2]
(IF 2 marks not scored, allow 1 mark
for the correct formula of one of
the ions)
(ii)add aluminium and sodium hydroxide
[1] warm and test the gas produced [1]
gas produced turns red litmus blue [1]
25
8 (a) (i)add (aqueous) sodium hydroxide [1]
iron(II) salts give green precipitate
[1] iron(III) salts give red-brown
precipitate [1]
(ii)aqueous ammonia contains OH–
ions [1] precipitates are the same /
both iron(II) hydroxide and iron(III)
hydroxides are formed [1]
(b) (i)oxidation [1] of iron(II) ions to iron
(III) ions [1]
(ii)Fe2+ → Fe3+ + e– [1]
(c) (i)add excess iron [1] to dilute sulfuric
acid [1] filter (excess solid) [1] heat
filtrate to point of crystallisation / heat
to form saturated solution [1] filter off
crystals / pick out crystals [1]
(ii)Fe(s) + H2SO4(aq) → FeSO4(aq) + H2(g)
(1 mark for correct formulae, 1 mark
for correct state symbols)
Unit 13 answers
Summary questions
13.1
1 proton; electrons; eight; groups; chemical; outer
2 (a)less metallic across a period / metals to the
left and non-metals to the right
(b)For Groups I to III charge is positive and
numerical value of charge = group number.
For Groups V to VII charge is negative and
numerical value of charge = group number.
Group IV only forms ions lower down group.
Group VIII does not form ions.
13.2
1 alkali; hydrogen; hydroxide; increases; fizzes;
surface; rapidly; fire
2 any value between and including 400 to 700°C
3 2Na + 2H2O → 2NaOH + H2
13.3
1 halogens; diatomic; decreases; chlorine; liquid;
iodine
2 chlorine is more reactive than bromine
3 Cl2(aq) + 2KBr(aq) → 2KCl(aq) + Br2(aq)
26
13.4
1 group; noble; eight; inert; energy; remove;
electrons; outer
2 increases down the group
3 Below oxygen in the same group, so likely to be
simple molecular structure. Simple molecules
have relatively low melting and boiling points
and are poor conductors of electricity and heat.
Non-metal so oxide will be acidic.
13.5
1 block; middle; high; densities; coloured; catalysts
2 often have catalytic activity; do not react with
cold water very rapidly
3 iron(II) and iron(III) chlorides are coloured; iron
has different oxidation states / forms two types
of ion ALLOW: they are catalysts
End of unit summary questions
1 alkali; soft; melting; darker; less; middle; high;
coloured; oxidation
2 chlorine: a green poisonous gas
bromine: a reddish-brown liquid
lithium: the least reactive of the alkali metals
neon: an unreactive gas
potassium: a metal that catches fire when it
reacts with water
iron: a metal with a very high melting point
3 Transition element has high melting point /
boiling point; high density; harder / stronger;
catalytic activity; coloured compounds; several
oxidation states / several types of ions; does not
react rapidly with cold water ALLOW: reverse
arguments for Group I metal.
4 (a)higher density down group; lower melting
and boiling points down the group; softer
down the group
(b)higher melting and boiling points down the
group; higher density down group; darker
in colour down group
5 lithium fizzes slowly but does not catch fire
but potassium fizzes violently and catches fire;
lithium remains solid but potassium melts
into a liquid ball; lithium disappears slowly but
potassium disappears rapidly
6 (a)sodium + water → sodium hydroxide +
hydrogen
(b)sodium + chlorine → sodium chloride
(c)chlorine + potassium iodide → iodine +
potassium chloride
7 chlorine reacts with potassium bromide
because chlorine is more reactive than bromine
so displaces the bromine from the bromide;
bromine does not react with potassium chloride
because bromine is less reactive than chlorine,
so cannot displace the chlorine from potassium
chloride
8 (a)2Li + 2H2O → 2LiOH + H2
(b)Br2(aq) + 2NaI(aq) → 2NaBr(aq) + I2(aq)
9 Decreases across period because more difficult
to form positive ions (because across a period the
force of attraction between the nucleus and the
electrons in the same outer shell increases)
Practice questions
1 D [1]
2 B [1]
3 (a) (i)values between 25 and 50°C (inclusive) [1]
(ii)values between 850 and 1250°C
(inclusive) [1]
(b)more reactive / explosive / very very
reactive [1]
(c)1 mark each for any 3 of: violent fizzing /
lots of bubbles / disappears / bursts into
flame / lilac (flame) / sparks
(d) (i)red litmus [1] turns blue [1]
(ii)potassium + water → potassium
hydroxide [1] + hydrogen [1]
4 (a)proton number [1]
(b)Period 3 [1]
(c) (i)F and Cl (both needed) [1]
(ii)Ne and Ar (both needed) [1]
(iii)Li and Na (both needed) [1] ALLOW: Be
in place of Li or Na
(iv)B [1]
(v)carbon [1] nitrogen [1]
(vi) Li [1]
5 (a)Both simple molecules / argon monatomic
and chlorine diatomic [1]
have low boiling points / weak forces of
attraction between molecules [1]
(b)Full outer shell of electrons / 8 electrons
in outer shell [1] takes too much energy to
add / remove / share electrons / energetically
stable electron configuration [1]
(c)molecule made up of two atoms [1]
(d)Cl2(g) [1] 2(HCl) [1]
(e) (i)chlorine + potassium bromide →
bromine [1] + potassium chloride [1]
(ii)colourless ALLOW: yellow-green [1] to
red-brown [1]
(iii)bromine is less reactive than chlorine [1]
6 (a)across the period more electrons added
[1] one (electron added) as atomic number
goes up by 1 [1] (electrons added) to
outer shell [1] ALLOW: marks for correct
electronic structures e.g. 2,8,1; 2,8,2; 2,8,3
as you go across the period gets 3 marks
(b)metals have low number of / 1,2,3 electrons
in outer shell [1] easier to remove electrons
from outer shell if nuclear charge is lower
[1] non-metals have higher number of
electrons in outer shell / 5/6/7 electrons in
outer shell [1] easier to gain electrons to
reach stable electronic configuration [1]
(c)density increases down the group [1]
reactivity decreases down the group [1]
(d) (i)bromine less reactive than chlorine [1]
(ii)Br2(aq) + 2KI(aq) → 2KBr(aq) + I2(aq)
(1 mark for correct species; 1 mark
for correct balance; 1 mark for correct
state symbols)
(iii)Cl2(aq) + 2OH−(aq) → Cl−(aq) + ClO−(aq)
+ H2O(l) [2] IGNORE state symbols
IF 2 marks not scored, allow 1 mark for
OH− and Cl−
7 (a)strontium forms ions more easily [1]
because it is easier to remove the outer
electrons from the larger atom / attraction
between outer electron and nucleus
smaller [1]
(b) (i)1 mark each for any 2 of: calcium
disappears / fizzing / effervescence
or bubbles ALLOW: solution becomes
cloudy
27
(ii)Ca + 2H2O → Ca(OH)2 + H2 (1 mark
for correct species; 1 mark for correct
balance)
(c)Elements in same group have similar
properties / Si should have similar
properties to C [1] has a giant structure like
carbon [1] AND 1 mark each for 2 suitable
properties: high melting point / high boiling
point; electrical insulator / semiconductor;
hard IGNORE: density
Unit 14 answers
Summary questions
14.1
1 potassium; cold; hydroxide; iron; steam; hydrogen
2 copper is above gold in the reactivity series /
copper is more reactive.
3 (a)no reaction
(b)reacts to form tin oxide and hydrogen
14.2
1 carbon; reduced; metals; heated; reducing;
oxygen
2 (a)2Ca + O2 → 2CaO
(b)2ZnO + C → 2Zn + CO2
(c)Mg + CuO → MgO + Cu
3 aluminium forms an oxide layer on its surface
which is unreactive and sticks strongly to the
surface of the metal.
14.3
1 extract; ores; bauxite; iron; carbon; zinc
2 It is above carbon in the reactivity series
ALLOW it takes too much energy (or too high a
temperature) to be economic
3 (a)SnO2 + 2C → Sn + 2CO
C is oxidised
(b)Fe2O3 + 3CO → 2Fe + 2CO2
CO is oxidised
14.4
1 displace; less; solution; more; outer
2 (a)CuSO4 + Mg → Cu + MgSO4
Cu2+ + Mg → Cu + Mg2+
28
(b)2AgNO3 + Cu → 2Ag + Cu(NO3)2
2Ag+ + Cu → 2Ag + Cu2+
3 copper is below iron in the reactivity series / copper
is too unreactive to donate electrons to iron ions
End of unit summary questions
1 water; sodium (potassium); potassium
(sodium); alkali; hydroxides; oxide; hydrogen
2 (a)calcium, magnesium, zinc, iron
(b)calcium, magnesium
(c)(calcium), magnesium, zinc, iron
(d)potassium above calcium; silver between
copper and gold
3 sodium: a metal that reacts with water to form
an alkaline solution
copper: a pinkish-brown metal that is not very
reactive
iron: a metal that reacts with steam but not with
cold water
potassium: a metal above sodium in the
reactivity series
magnesium: a reactive metal that reacts slowly
with cold water
4 The more reactive the metal, the more easily it
forms a positive ion
5 aluminium forms an oxide layer on its surface
which is unreactive and sticks strongly to the
surface of the metal.
Practice questions
1 C [1]
2 B [1]
3 (a)sodium AND calcium [1]
(b) (i)zinc [1]
(ii)3(Fe) [1] 4(H2O) [1] 4(H2) [1]
(iii)ion is oxidised [1] because it gains
oxygen [1] water is reduced since it
loses oxygen [1]
(c) (i)magnesium + hydrochloric acid →
magnesium chloride + hydrogen [1]
(ii)Mg + 2HCl → MgCl2 + H2
(1 mark for correct formulae; 1 mark
for correct balance)
(d) (i)One mark each for any two of: flames /
white powder formed / pink (or
brown) solid formed
(ii)magnesium + copper(II) oxide →
magnesium oxide + copper [1]
(iii)copper(II) oxide because it loses its
oxygen [1]
4 (a)rock [1] which contains a metal
(compound) that can be extracted [1]
(b) (i)ZnO + CO → Zn [1] + CO2 [1]
(ii)carbon monoxide [1] it gains
oxygen [1]
(c) (i)Zn lower in the reactivity series /
zinc doesn’t lose electrons as
easily / potassium higher in
reactivity series / potassium loses
electrons more easily [1]
(ii)2 (K) 2(H2O) 2(KOH) [1]
5 (a)zinc [1] removes oxygen from copper
oxide / oxidation number of Zn increases /
zinc transfers electrons to copper ions [1]
(b)zinc atoms to copper ions [1]
(c)zinc atoms release electrons more readily
than copper atoms [1]
(d)zinc is lower than magnesium in the
reactivity series [1] so loses its electrons /
forms ions less readily [1]
(e) (i)1 mark each for any 2 of: magnesium
disappears / magnesium coated with
pink (or brown) layer OR pink deposit
formed / colour of copper(II) sulfate
fades / effervescence or bubbles
(ii)Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s)
(1 mark for correct formulae; 1 mark
for correct state symbols)
6 (a) (i)1 mark each for any two of: sodium
disappears / bubbles or effervesces /
fizzing sound / moves around on the
surface of the water
(ii)Mg(s) + H2O(g) → MgO(s) + H2(g)
(1 mark for correct formulae; 1 mark
for correct state symbols)
(b) (i)reaction where one atom or ion
replaces another [1]
(ii)magnesium oxidised [1] because
oxidation number of Mg increases /
ox. no. goes from 0 to +2 [1] iron ions
reduced [1] because oxidation number
of Fe(II) decreases / ox. no. goes from
+2 to 0 [1]
(c) (i)mix magnesium power with
aluminium oxide [1] use magnesium
fuse to ignite the mixture [1]
(ii)3Mg + Al2O3 → 2Al + 3MgO
(1 mark for correct formulae; 1 mark
for correct balance)
(iii)too dangerous / cannot scale it up
sufficiently [1]
(iv)aluminium forms oxide layer [1] oxide
layer is unreactive [1] oxide layer not
easily rubbed off [1]
Unit 15 answers
Summary questions
15.1
1 blast; hematite; air / limestone; limestone / air;
reduces; oxide
2 (a)iron(III) oxide + carbon monoxide → iron +
carbon dioxide
(b)calcium carbonate → calcium oxide +
carbon dioxide
calcium oxide + silicon (IV) oxide → calcium
silicate
3 Fe2O3 + 3CO → 2Fe + 3CO2
CaCO3 → CaO + CO2
CaO + SiO2 → CaSiO3
15.2
1 oxygen; steel; hydrated; flakes; surface; rust
2 oxygen and water cannot get through the layer
of tin to reach the iron
3 Magnesium is more reactive than iron so
magnesium corrodes in preference to iron.
Magnesium loses electrons more readily than
iron. The electrons released prevent the iron
from oxidising.
15.3
1 mixture; non-metal; alloy; stronger; layers;
arrangement
29
2 B
3 In the pure metals the layers of atoms / ions
slide when a force is applied. Magnesium and
aluminium have different sized atoms. In the
alloy, these different sized atoms prevent the
layers from sliding easily when a force is applied.
15.4
1 different; carbon; mild; car; stainless; cutlery
2 aluminium is relatively unreactive because of its
oxide layer which resists corrosion and does not
easily flake off
3 Any two of: harder / stronger / does not corrode
as easily as the pure metal
End of unit summary questions
1 brass: copper, zinc
stainless steel: iron, carbon, chromium
mild steel: iron, carbon
2
P
Q
S
R
Q
3 blast; monoxide; coke; air; decomposes;
calcium; impurities; slag
4 aluminium: aircraft bodies
mild steel: car bodies
stainless steel: cutlery
copper: electrical wiring in the home
zinc: galvanising iron roofs
5 (a)electrolysis
(b)heating with carbon
(c)electrolysis
(d)heating with carbon
(e)electrolysis
6 C and D
Practice questions
1 D [1]
2 C [1]
3 B [1]
30
4 (a)hematite / iron ore [1] air [1] limestone [1]
(b) (i)F [1]
(ii) D [1]
(iii)B [1]
(c) (i)carbon monoxide + iron(III) oxide →
iron + carbon dioxide
carbon dioxide as product [1] rest of
equation correct [1]
(ii)C + CO2 → 2CO
correct symbols [1] correct balance [1]
(d) (i)oxygen / air [1] water [1]
(ii)1 mark each for any 2 of: coating or
covering with zinc (or galvanising) /
plastic / tin / chromium etc / greasing
(or oiling) / sacrificial protection with
magnesium / zinc
5 (a)mixture [1] of metal and one or more other
elements [1]
(b)iron [1] carbon [1]
(c)chromium / nickel [1]
(d) (i)cutlery / chemical plant / surgical
instruments / other suitable uses [1]
(ii)1 mark each for any two of: harder /
stronger / more resistant to corrosion
6 (a)iron [1] tin [1] ALLOW: zinc [1]
(b)Any two pairs of: aircraft [1] low density [1];
food containers [1] resistance to corrosion
[1]; (overhead) power cables [1] good
electrical conductor / low density [1]
(c) (i)high temperature / heat [1]
(ii)Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)
3 (CO) [1] 2(Fe) [1]
(d) (i)decomposes [1] to calcium oxide and
carbon dioxide [1]
(ii)(calcium oxide) reacts with impurities /
silicon dioxide in the ore / removes
impurities in the ore [1] to form slag /
calcium silicate [1]
7 (a)hematite [1]
(b) (i)carbon / coke reacts with oxygen / air
[1] to form carbon dioxide [1] carbon
dioxide reacts with excess carbon /
coke [1]
(ii)Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)
correct symbols [1] correct balance [1]
state symbols correct [1]
(c)iron(III) ions gain electrons [1] carbon loses
electrons [1] gain of electrons is reduction
and loss of electrons is oxidation [1]
(d) (i)hydrated [1] iron(III) oxide [1]
(ii)zinc layer on surface of iron [1]
prevents oxygen / air or water from
penetrating to the iron [1] zinc is more
reactive than iron [1] so corrodes
instead of iron [1]
8 (a)mixture [1] of metal and one or more other
elements [1]
(b)carbon [1] nickel / chromium ALLOW: other
transition elements e.g. vanadium [1]
(c)cutlery / chemical plant / surgical
equipment [1] harder / stronger / more
resistant to corrosion [1]
(d) (i)See Figure 15.3.1(b) layers of atoms
[1] alloying metal atoms arranged
randomly [1]
(ii)In iron the layers of atoms / ions slide
when a force is applied. [1] In the alloy,
the alloying metal / carbon has atoms
of different size from iron atoms. [1]
The different sized atoms prevent the
layers from sliding easily when a force
is applied. [1]
Unit 16 answers
Summary questions
16.1
1 Haber; nitrogen; compressed; converter;
kilopascal; iron; rate
2 If temperature is too high, the yield is poor. If the
temperature is too low, the rate of reaction is
too slow.
3 Nitrogen from the air. Hydrogen from cracking
hydrocarbons or from reacting steam with
methane.
16.2
1 phosphorus / potassium; potassium /
phosphorus; fertilisers; soil; elements;
harvested
2 Titrate the potassium hydroxide with
phosphoric acid (with potassium hydroxide
in the flask with a suitable indicator). Record
the reading on the burette when the indicator
changes colour. Repeat the titration without the
indicator. Warm solution to reduce volume and
then leave to crystallise (in a drying oven).
3 ammonia + nitric acid → ammonium nitrate
16.3
1 (a)copper(II) oxide + sulfuric acid → copper(II)
sulfate + water
(b)sodium hydroxide + sulfuric acid → sodium
sulfate + water
2 (a)Ba(OH)2 + H2SO4 → BaSO4 + 2H2O
(b)CaCO3 + H2SO4 → CaSO4 + CO2 + H2O
3 equilibrium; more; SO2; volume; temperature;
SO3
16.4
1 fossil; sulfur; water; sulfurous; oxidised; sulfuric
2 any two of: tree leaves damaged or trees die /
aquatic life in lakes and rivers dies / soil too
acidic to grow crop plants / buildings made
from carbonate rocks will be eroded / metal
bridges and iron railings corrode
3 (a) S + O2 → SO2
(b)SO2 + H2O → H2SO3
End of unit summary questions
1 ammonium nitrate: a salt used as a fertiliser
nitrogen dioxide: a gas responsible for acid rain
methane: a gas used to produce hydrogen
ammonia: an alkaline gas used to make
fertilisers
2 crops; nitrate / phosphate; phosphate / nitrate;
elements; harvested; potassium
3 (a)ammonia and sulfuric acid
(b)potassium hydroxide and phosphoric acid
(c)ammonia and nitric acid
4 (a)nitric acid + potassium hydroxide →
potassium nitrate + water
(b)sulfur + oxygen → sulfur dioxide
(c)nitrogen + oxygen → nitrogen dioxide
(d)sulfuric acid + calcium carbonate →
calcium sulfate + carbon dioxide + water
31
5 (a) H2SO4 + MgO → MgSO4 + H2O
(b) H2SO4 + Zn → ZnSO4 + H2
(c) H2SO4 + 2NaOH → Na2SO4 + 2H2O
(d) H2SO4 + Na2CO3→ Na2SO4 + CO2 + H2O
Practice questions
1 A
2 B
3 (a)to increase crop yield / to make plants grow
faster [1]
(b)nitrogen [1] phosphorus [1] potassium [1]
(c)Put ammonia in a flask with indicator [1]
add sulfuric acid from burette [1] until
indicator changes colour [1] record volume
of sulfuric acid used [1] repeat experiment
using same volume of acid but without
indicator [1]
(d)ammonia + nitric acid → ammonium nitrate
ammonia + nitric acid [1] rest of equation
correct [1]
4 (a)pH 4.5 [1]
(b)sulfur dioxide: burning fossil fuels or
burning named fossil fuel / volcanoes[1]
nitrogen dioxide: car engines / hightemperature furnaces / bacterial
denitrification / lightning [1]
(c)nitrogen dioxide + water → nitric acid +
nitrous acid [2]
If 2 marks not scored, 1 mark for nitrogen
dioxide reacts with water (in atmosphere)
nitric acid formed
(d)2SO2 + O2 → 2SO3
O2 [1] correct balance [1]
(e)chemical erosion / building eaten away
ALLOW: building crumbles [1] reaction
between acid and carbonate [1]
5 (a)ammonia [1] phosphoric acid [1]
(b)Put ammonia in a flask with indicator
[1] add phosphoric acid from burette [1]
until indicator changes colour [1] record
volume of phosphoric acid used [1] repeat
experiment using same volume of acid but
without indicator [1]
32
(c)solution; phosphate; evaporated;
concentrated; filtered; dried
6 correct = 4 marks; 4 or 5 correct = 3 marks;
2 or 3 correct = 2 marks; 1 correct = 1 mark
(d)1 mark each for any two of: nonpoisonous nitrate / non-poisonous soluble
phosphate / suitable potassium salt /
ammonium salt
6 (a)the air [1]
(b)methane (+ steam) ALLOW: cracking
hydrocarbons [1]
(c)equilibrium moves in the direction of fewer
moles of gas / decrease in gas volume [1] to
oppose / reduce the increase in pressure [1]
3 moles of gas on the left (reactants)
2 moles of gas (products) on right [1]
(d)high pressure can be dangerous [1] need
for thicker pressure vessels which are more
expensive / too much energy needed to
produce increased pressure [1]
(e)Increase in temperature decreases the
yield of ammonia [1] reaction is exothermic
[1] so increasing temperature favours the
endothermic reaction which is in favour of
reactants [1]
(f)Higher temperature decreases yield of
ammonia [1] at lower temperatures the
rate of reaction is too slow for useful rate [1]
7 (a)yield of SO3 decreases [1] equilibrium
moves in the direction of greater number of
moles of gas / increase in gas volume [1] to
oppose the decrease in pressure [1]
(b)The yield is high already [1] increasing
pressure is more expensive than increased
financial returns on the yield [1]
(c)Increase in temperature decreases the
yield of SO3 [1] reaction is exothermic [1]
so increasing temperature favours the
endothermic reaction which is in favour of
reactants [1]
(d) (i)increases the rate of reaction [1] lowers
the activation energy of the reaction [1]
catalyst not used up / is unchanged at
the end of the reaction [1]
(ii)none / has no effect on the position of
equilibrium [1]
(iii)V has high melting point [1] V has high
density [1]
8 (a)has two hydrogen ions that can be
replaced by other ions [3]
If 2 marks not scored: 1 mark for idea of two
hydrogens per molecule
(b)acid is a proton donor / substance which
ionises to form H+ ions [1]
acid which is completely dissociated /
ionised in solution [1]
(c)H2SO4(aq) + Zn(s) → ZnSO4(aq) + H2(g)
correct formulae [1] correct state
symbols [1]
(d)H2SO4 + CaCO3 → CaSO4 + CO2 + H2O [2]
If 2 marks not scored CO2 + H2O [1]
(e)Sulfur in fossil fuel reacts with oxygen /
burns [1] to form sulfur dioxide [1]
sulfur dioxide oxidised to sulfur trioxide in
atmosphere [1]
sulfur trioxide reacts with water (in
atmosphere) [1]
Unit 17 answers
Summary questions
17.1
1 nitrogen; oxygen; argon; air; dioxide; warming;
climate
2 (a)complete combustion of carbon-containing
fuels / decomposition of carbonates /
action of acid on carbonate / respiration
(b)decomposition of vegetation / waste gases
from digestion of animals / melting of
permafrost / paddy fields
(c)vehicle engines / high temperature
furnaces / lightning
3 incomplete combustion of carbon-containing
compounds / combustion in limited air (or
oxygen), CO is toxic / poisonous
17.2
1 Any 3 of: burning fossil fuels / decomposition
of carbonates / action of acid on carbonate /
respiration / decay of vegetation
2 photosynthesis
3 carbon; atmosphere; photosynthesis; oxygen;
glucose; water; uses
17.3
1 waste product of digestion in animals / paddy
fields / melting of permafrost / decomposition
of vegetation
2 any two effects of global warming e.g.
melting of ice caps / glaciers ; sea level rise;
desertification; more extreme weather; more
flooding
3 methane; greenhouse; global; absorb; radiated;
atmosphere; increase
17.4
1 acid rain / stated effect of acid rain;
increased global warming / greenhouse gas /
photochemical smog
2 need to remove sulfur dioxide from factory /
power station emissions which cause acid
rain; use a spray of calcium oxide (or calcium
carbonate) to react with sulfur dioxide; calcium
sulfite formed removed as a solid
3 exhaust; nitrogen; monoxide; converter;
reduced; oxidised
17.5
1 drinking; filter; insoluble; chlorine; bacteria;
carbon
2 (a)respiration
(b)for bones / for cartilage / for proper enzyme
function / for chlorophyll (or other named
biological component)
3 more oxygen nearer the surface for respiration /
more light for photosynthesis by plants which
produce oxygen
17.6
1 metal; toxic; microbes; disease; phosphates;
deoxygenation; aquatic
2 (a)Waste water / solids from human
household activities e.g. washing / toilet
(b)removal of oxygen
(c)poisonous / can kill you
3 trap animals or fish / harm digestive system of
aquatic organisms / poisonous compounds
washed out / reduce oxygen getting to blood
33
End of unit summary questions
1 particulates: cancer
nitrogen oxides: photochemical smog and
acid rain
methane: increased global warming
carbon monoxide: stops respiration
2 burning / combustion of carbon-containing
substances; in limited air / oxygen (or
combustion is incomplete)
3 dry; 78%; 21%; noble; dioxide; increased; global;
climate
4 CH4: cows and sheep
CO: incomplete combustion of C2H6
SO2: burning fossil fuel containing sulfur
compounds
NO: lightning
CO2: complete combustion of C2H6
5 Any 3 of: burning fossil fuels / decomposition
of carbonates / action of acid on carbonate /
respiration / decay of vegetation
6 (a)any two of nitrous oxide / nitric oxide /
nitrogen dioxide (allow nitrogen(I) oxide /
nitrogen(II) oxide / nitrogen(IV) oxide)
(b)high temperature and pressure causes
nitrogen and oxygen to combine
(c)carbon monoxide and oxides of nitrogen
from car engine react in catalysed reaction
in the convertor to produce nitrogen and
carbon dioxide
7 infrared; energy; greenhouse; methane; carbon;
temperature; global; change
Practice questions
1 D [1]
2 D [1]
3 (a) (i)oxygen [1] carbon dioxide [1] argon [1]
(ALLOW: one other noble case in place
of oxygen or carbon dioxide)
(ii)(oxygen) 21% / (carbon dioxide)
0.04% / (argon) values between 0.09
−1% [1]
34
(b) (i)combustion of carbon-containing
compounds / named carbon
compound [1]
combustion incomplete / combustion
in limited air or oxygen [1]
(ii)toxic / poisonous [1]
(c) (i)1 mark each for any two of
decomposition of vegetation / waste
gases from digestion of animals /
melting of permafrost / paddy fields
(ii)it is a greenhouse gas / it absorbs
energy [1] increases global
warming / increases warming of the
atmosphere [1]
(iii)melting of ice caps / glaciers; sea level
rise; desertification; more extreme
weather; more flooding [1]
4 (a)0.04% [1]
(b)glucose + oxygen → carbon dioxide + water
glucose on left [1] oxygen on left [1] water
on right [1]
(c) (i)1 mark each for any two of:
combustion of carbon-containing
fuels (or suitable named fuel) /
reaction of acids with carbonates /
thermal decomposition of carbonates
(ii)photosynthesis [1]
(d)water creatures / fish need it for respiration [1]
(e)(essential) minerals / non-toxic metal ions [1]
(f)bacteria / microbes grow / live in
sewage [1] they cause disease in aquatic
organisms / fish / humans [1]
(g) (i)carbon removes bad tastes / bad
odours [1]
(ii)chlorine kills bacteria / microbes [1]
5 (a)plants form glucose [1] by absorbing carbon
dioxide [1] and releasing oxygen [1] in the
presence of chlorophyll [1] and light [1]
(b)6CO2 + 6H2O → C6H12O6 + 6O2
1 mark for correct formulae [1] 1 mark for
correct balance [1]
(c)combustion of carbon-containing fuels (or
suitable named fuel) / reaction of acids
more use of solar power / hydroelectric
power etc [1] which does not produce
greenhouse gases [1]
less livestock farming [1] so less methane
produced [1]
use of carbon capture in power stations
[1] so less carbon dioxide gets into the
atmosphere [1]
Unit 18 answers
Summary questions
C=C
−
−
18.1
1 ethane; homologous; functional; atom;
compound; chemical
2 (a)alcohol, -OH
(b)alkene,
−
(c)carboxylic acid,
−
O
−
−C
=
H
H
ethanol
=
−
−
H−C− C−O−H
H−C− C−O−H
−
−
−
O−H
3 any three of: same general formula / trend
in physical properties / similar chemical
properties / differ by –CH2 group between
successive members
18.2
1 members; prefixes; prop-; pent-; number; chain;
butane; three
2 (a)butane (b) propene
3
H H
H O
−
with carbonates / thermal decomposition
of carbonates [1]
(d)on the left: 6 (O2) [1]
on the right: 6 [1] + H2O [1]
(e) (i)gas which absorbs (infrared) energy [1]
increases global warming / increases
warming of the atmosphere [1]
(ii)increased use of fossil fuels / increased
livestock farming [1]
6 (a)N2 + O2 → 2NO [2]
correct formulae [1] correct balance [1]
(b)oxides of nitrogen react [1] with carbon
monoxide [1] to form nitrogen and carbon
dioxide [1]
(c)reducing reagent is C6H14 and oxidising
agent is NO2 [1] carbon is oxidised to
carbon dioxide (by NO2) / oxidation number
of carbon increases [1] nitrogen (in NO2) is
reduced (by the hydrocarbon) / oxidation
number of N decreases [1]
(d)pass waste gases through spray / aqueous
slurry [1] of calcium oxide ALLOW: calcium
hydroxide / calcium carbonate [1] calcium
sulfite formed is removed as solid [1]
CaO + SO2 → CaSO3 ALLOW: suitable
equations for calcium hydroxide / calcium
carbonate [1]
(e)idea of light involved in the reaction [1] NO
reacts with oxygen to form ozone [1] which
reacts with (unburned) hydrocarbons from
vehicle [1]
7 (a) (i)combustion where hydrocarbon in
excess / air or oxygen is limiting [1]
(ii) 2CH4(g) + 3O2(g) → 2CO(g) + 4H2O(l)
correct formulae [1] correct balance
[1] correct state symbols [1]
(b)gas which absorbs (infrared) energy [1]
increases global warming / increases
warming of the atmosphere [1]
(c)More livestock [1] ALLOW: more melting of
permafrost
(d)Two distinct suitable strategies (1 + 1)
relevant explanation of each (1 + 1) e.g.
more electric cars [1] so that less carbon
dioxide gets into the atmosphere [1]
H
ethanoic acid
18.3
1 (a)CH3CH=CH2
(b)CH3COOH
(c)CH3CH2CH2CH2CH2CH3
2 (a)2-methylpropane / methylpropane
(b)propene
3 CH3CH2CH2CH3 CH3CH(CH3)CH3
35
End of unit summary questions
−
36
−
−
−
1 naphtha: making chemicals
bitumen: surfacing roads
diesel: fuel for diesel engines
kerosene: jet fuel
2 ethane; homologous; alkanes; functional;
alcohols; alkenes
3 (lowest) refinery gas, naphtha, kerosene; fuel oil;
bitumen (highest)
4 methane: the main constituent of natural gas
coal: a solid fuel that often contains sulfur
petroleum: a thick liquid mixture of hydrocarbons
fraction: a group of molecules with a similar
range of boiling points
hydrogen: a gaseous fuel that forms only water
when it burns
5 (a) alcohol, -OH
(b)alkene,
C=C
(c)carboxylic acid,
O
−
−C
=
O−H
6 (a)compounds with the same molecular
formula but different structural formula
CH3 − CH − CH3
(b) (i) CH3 − CH2 − CH2 − CH3
−
18.4
1 fractional; petroleum; volatile; viscous; excess;
water
2 (a)methane + oxygen → carbon dioxide + water
(b)hydrogen + oxygen → water
3 2C2H6 + 7O2 → 4CO2 + 6H2O
18.5
1 fractions; hydrocarbons; boiling; tower; higher;
condense
2petroleum heated / vaporised
hydrocarbons fractionally distilled in tall tower /
column
temperature gradient in tower / column high at
bottom, low at top
shorter chain hydrocarbons move further up
column than longer chain hydrocarbons
fractions condense where temperature in
column falls just below boiling point
3 (a)fuel for ships / home heating / power stations
(b)fuel for jet aircraft / heating
(c)chemical feedstock / to make chemicals
CH3
(or displayed / structural formula)
(ii)CH3―CH=CH―CH3 CH2=CH―CH2―CH3 (or
displayed / structural formula)
7 any three of: same functional group / same
general formula / trend in physical properties /
similar chemical properties / differ by –CH2−
group between successive members
Practice questions
1 B [1]
2 D [1]
3 (a)(i)group of hydrocarbons [1] with similar
range of boiling points [1]
(ii)compound containing carbon and
hydrogen only [2]
If 2 marks not scored, 1 mark for
compound containing carbon and
hydrogen
(b)different fractions have different (range of)
boiling points [1]
temperature gradient in tower / column
higher at bottom and lower at top [1]
each fraction comes off where the
temperature in the tower / column falls
below its boiling point [1]
(c) (i)jet fuel / fuel for heating [1]
(ii)two fractions other than kerosene e.g.
refinery gas / bitumen (1 +1)
two uses specific to the fractions
chosen e.g. for refinery gas: fuel for
heating / cooking [1] for bitumen:
making roads [1]
(d)fractions [1] shorter [1] lower [1] mass [1]
condense [1]
4 (a)exothermic [1]
(b) (i)methane / ethane / propane /
butane [1]
− −
−
−
−
−
−
[1]
H
(ii)CH3CH(CH3)CH3
(e) (i)Compounds with the same molecular
formula but with different structures
(ii)CH3― CH=CH―CH3 [1]
CH2=CH―CH2―CH3 [1]
CH2 = C − CH3
−
CH3
(or displayed / structural formula)
Unit 19 answers
Summary questions
−
−
19.1
1 hydrocarbons; single; unreactive; substitution;
excess; carbon; water.
2 compound containing carbon and hydrogen
only which has only single covalent bonds
3
H H
−
H − C − C − Cl
H
H
−
−
−
−
−
−
−
−
−
−
−
19.2
1 long; alkanes / alkenes; alkenes / alkanes; high;
catalyst; silicon
(b) H2
2 (a)C4H8
3 Shorter chain alkanes and alkenes are in short
supply; longer chain alkanes are not in short
supply; cracking produces more petrol / more
alkenes / more short-chain hydrocarbons /
hydrogen / ethene
19.3
1 hydrocarbon; saturated; bromine; colourless;
remains; shaken
2 CH3CH=CH2 is unsaturated because it has a C=C
double bond
CH3CH2CH3 is saturated because it has only
single bonds
(b)
H H H H
3 (a) H H H
−
(d)family / group of compounds with similar
chemical properties [1] due to the same
functional group [1]
5 (a)A and C [1]
(b)C [1]
(c)carboxylic acid [1]
(d)methanol [1]
(e)CH4O [1]
(f)displayed formula for alkane other than
ethane (see Topic 18.2 in coursebook) [1]
(g) (i) –OH [1]
(ii) –COOH [1]
6 (a)D [1]
(b)A [1]
(c)gasoline [1] molecules (or chains) are
shorter / molecules (or chains) have lower
mass / attractive forces between molecules
lower [1]
(d)two other fractions e.g. refinery gases /
naphtha (1 + 1)
position in column made clear e.g. refinery
gases above gasoline [1] naphtha between
gasoline and kerosene [1]
uses: refinery gases: gas for heating and
cooking [1] naphtha: for making chemicals [1]
(e) (i)more volatile higher up the column /
less volatile lower in the column [1]
(ii)more viscous lower down the
column / less viscous higher in the
column [1]
7 (a)family / group of compounds with similar
chemical properties [1] due to the same
functional group [1]
(b)CnH2n [1]
(c)C5H12 [1]
H−C−C−C−H
H H
−
H
H
H−C−H
H
H
−
−
H−C− H
(d) (i)
−
(ii)any suitable e.g. ethanol / pentane /
kerosene [1]
(iii)coal / wood [1]
(c) (i)compound of hydrogen and carbon
only [1] which contains only single
bonds [1]
(ii)C2H6 [1]
H
(iii)
−
H−C−C−C−H
H−C−C−C−C−H
H Br Br
H H H H
37
(c)C2H4 + H2O → C2H5OH
(d)C5H12 + 8O2 → 5CO2 + 6H2O
(e)2CH3COOH + 2Na → 2CH3COONa + H2
4 (a)addition / hydration
(b)oxidation / redox
(c)combustion / oxidation
(d)esterification / addition-elimination
5 (a)300°C; 6000 kPa; acid catalyst
(b)hydrogen; nickel catalyst; 60°C
(c)acidified potassium manganate(VII);
reflux / heat
(d)ethanol; acid catalyst / sulfuric acid; warm
gently ALLOW: room temperature
6 Divide portion of ethanol into 2. Oxidise one
portion to ethanoic acid by refluxing with
acidified potassium manganate(VII). Purify the
sample to get pure ethanoic acid (details not
needed). Warm the ethanoic acid with the other
portion of ethanol in the presence of an acid
catalyst to get ethyl ethanoate.
(b)
(c)
7 (a)
−
− −
−
−
−
O−H
−
H
O
−
−
−
−
H H
−
−
−
−
−
−
− −
−
−
H−C−C−C−H
H
H−C−H
H
H
H−C−C−C−H
H
H
H
Practice questions
1 B [1]
2 A [1]
3 (a) (i)C6H14 [1]
(ii)ethene [1]
−
−
−
H H
−
−
−
−
−
−
−
−
fermentation of glucose
cracking: the breaking down of long-chain
alkanes to alkenes and shorter-chain alkanes
unsaturated: organic compounds containing
C=C double bonds
addition: a reaction in which two or more
compounds combine to form only one compound
saturated: organic compounds containing only
single C–C bonds
2 bromine; orange; decolourises; ethane; bonds;
added; ethene.
3 (a)C10H22 → C2H4 + C8H18
(b) C
H + Br2 → C2H4Br2
2 4
−
−
−
−
−
−
=
−
−
H
H
(c)
H H H
H H
H H H
H
O
End of unit summary
H − C − C =questions
C
H−C−C−C−C
H
O−H
H the products of the
H H H
1 ethanol: one of
38
H H
H−C−C−C−C
H
H−C−H
H
H
−
−
−
−
−
−
H − C −(a)C − O − C − C − C − H (b)
H
H
H
H H H
=
H O
−
(b)
H
=
−
H
H−C−C=C
−
H − C − O− Na+
−
H
=
19.4
1 functional; ethanol; ethene; steam;
fermentation
2 solvent; fuel
3 (a)CH3CH2CH2OH (b) CH3CH(OH)CH3
19.5
1 yeast; ferments; glucose; ethanol; carbon;
enzymes; catalyse
2 absence of oxygen; 25–35°C; ALLOW: catalyst /
yeast OR pH neutral
3 (a)low temperature required / renewable
source
(b)continuous method / fast rate of reaction /
ethanol of high purity
19.6
1 functional; hydrogen; salt; water; ethanoates
2 (a)ethanoic acid + potassium carbonate →
potassium ethanoate + carbon dioxide +
water
(b)ethanoic acid + zinc → zinc ethanoate +
hydrogen
O
3 (a)
C=C
H H [1]
(b)high temperature [1] (Al2O3/SiO2) catalyst [1]
(c) (i)substance containing C-C bonds
that are single only / substance only
containing single covalent bonds [1]
H
H
(ii)2CH3CH2COOH + K2CO3 →
2CH3CH2COOK [1] + H2O + CO2 (1 for
both small molecules)
correct balance [3]
(d) (i)potassium manganate(VII) [1]
(ii)acid catalyst [1] reflux / heat [1]
(iii)C2H5OH + 2[O] → CH3COOH + H2O
correct formulae [1] correct balance [1]
7 (a)(i)CH3CH=CHCH3 / CH2=CHCH2CH3 /
CH2=C(CH3)CH3 [1]
(ii)
H H H H
H H H
H
H−C− C−O−H
H
H
−
−
−
−
[2] (1 mark if OH instead of -O―H)
(ii) H H
C=C
−
−
−
−
−
−
−
−
H
−
−
−
−
−
−
−
− −
−
−
−
−
−
−
−
−
−
−
−
−
H
−
−
=
−
−
−
−
−
−
−
H−C− C−O−H
O
=
(ii)
H−C− O−H
[1]
(b) (i)acid catalyst [1] warm gently / room
temperature [1]
(ii)propyl methanoate [1]
−
−
−
−
−
H H H
−
O
=
[2] (1 mark if COOH without bonds)
(b)rate of reaction with metals / carbonates /
hydroxides is slower with ethanoic acid [1]
pH of ethanoic acid higher than that of
strong acid [1]
(c) (i)2CH3CH2COOH + Mg →
(CH3CH2COO)2Mg [1] + H2 [1] + [1] for
correct balance
[1]
H
−
H
H−C−O−C−C−C−H
H H H
H
H−C−
[1]
39
C=C−
−
−
H H [1]
(b)fermentation: temperature 25–35°C [1]
hydration: 300°C / high temperature [1]
H−C−C=C−C−H
C=C−C−C−H
H
H
H
H H
fermentation: atmospheric pressure [1]
hydration: high pressure / 6000 kPa [1]
H
fermentation: catalyst yeast [1] hydration:
H−C−H
H
H Hacid
H [1]
H
H H H
catalyst: (phosphoric)
H
H
=C−C−C−H
H−C−C=C−C−H
C=C−C−H
(c)glucose [1] → ( ethanol
+) carbon dioxideC[1]
H
H
H
H
H H
H
[1]
5 (a)Add to aqueous bromine [1] ethane:
(b) (i)UV light [1]
bromine remains orange [1] ethene:
bromine decolourised [1]
(ii)substitution / photochemical [1]
H
H
(b)
(c) (i)C2H4 + Br2 → C2H4Br2
H−C− C−H
formulae of reactants [1] formula of
[1]
H H
product [1]
(c) (i)breakdown / decomposition [1] of
(ii)addition [1]
long-chain alkanes [1] to short-chain
(iii)red / red-brown / brown colour of
alkanes [1] and alkenes / hydrogen [1] bromine [1] decolourised [1]
(ii)1 mark each for any 2 of: reduce
(d) (i)300°C ALLOW: high temperature [1]
amount of long-chain alkanes
6000 kPa ALLOW: high pressure [1]
wasted / produce more petrol (or
acid catalyst [1]
diesel) / produce ethene
(ii)CH3CH=CH2 + H2O → CH3CH(OH)CH3
(d)3(O2) [1] 2(CO2) [1] 3(H2O) [1]
formulae of reactants [1] formula of
(e)fuel [1] solvent [1]
product. ALLOW CH2CH2CH2OH as
(f)ethanoic acid + magnesium → magnesium
product [1]
ethanoate [1] + hydrogen [1]
H
8 (a) (i)
6 (a) H O
H−C− O−H
− −
−
−
−
−
(ii)substance containing hydrogen
and carbon [1] and no other
elements [1]
H H
4 (a) (i)
−
−
−
−
−
−
−
−
−
−
−
−
−
20.1
1 ethene; addition; monomer; molecules;
polymer
2 poisonous fumes when burned / landfill uses up
agricultural land or housing land / ideas of litter
or being an eyesore / defined effects on animals
e.g. fishing nets strangle them or block digestive
system
3 PET is hydrolysed to the monomers; monomers
repolymerised
20.2
1 (a)poly(butene) (b)poly(tetrafluoroethene)
(c)poly(ethenyl ethanoate)
2
CH3 CH3 CH3 CH3 CH3 CH3
−C−C−C−C−C−C−
H
H
H
H
−
−
F
−
HO − C −
F
H
O
=
(b)
− C − O−
20.4
1 amine; carboxylic acid
2 order; irregular; repeat; regular; unit
End of unit summary questions
1 ethene; chains; polymer; join; monomers
2 monomer: a simple molecule from which a
polymer is made
addition: a reaction where two or more
molecules combine to form only one product
polymer: a molecule made by combining
monomers
40
O
HO − C −
− C − OH
H O−
− OH
O
− C − OH
H2N −
− NH2
Practice questions
1 B [1]
2 B [1]
H
3 (a)
H
−
−
− C − N−
(b)
−
=
20.3
1 condensation; monomers; diamines;
polyamide; water; eliminated
(a)
O
2
−
F
=
C=C
−
F
−
3
H
=
H
=
Summary questions
poly(ethene): the name of a polymer formed
from C2H4 monomers
3 (a)positive: can be used as a fuel. negative:
release poisonous / acidic fumes when
burned.
(b)positive: can be used for useful articles /
plastic not wasted / plastic doesn’t litter
the environment etc.; negative: expense of
collecting / sorting / using fuel to collect,
sort etc.
(c)positive: reduces litter / no advantage.
negative: wastes space for crops / spoils
countryside / litter blows away in wind
4 poly(chloroethene): CH2=CHCl
poly(butene): C2H5CH=CH2
poly(ethenyl ethanoate): CH3COOCH=CH2
poly(propene): CH3CH=CH2
poly(ethene): CH2=CH2
5 a and e only
6 (a) and (b)
O
O
(a)
=
Unit 20 answers
C=C
[1]
(b)monomer [1]
(c)poly(ethene) [1]
(d)addition [1]
(e)C=C double bond [1]
(f) ―CH2CH2CH2CH2―
at least 4 CH2 groups ALLOW: displayed
structure [1]
continuation bonds [1]
4 (a)addition [1]
(b)―CH(CH3)―CH2―CH(CH3)―CH2―CH(CH3)―
CH2― (or correct displayed structure)
H H
−
H H
n
HO − C −
− C − OH
H2N −
=
(1 mark for each monomer)
(d) (i)
O
− NH2
O
=
=
=
Structure within the brackets correct [1]
Continuation bonds and brackets [1]
n outside brackets at bottom right [1]
5 (a)reaction of monomers to form a polymer [1]
with the elimination [1] of a small
molecule [1]
(b)amide [1]
O
(c) O
H
−
−
− N − C6 H4−N − C− C6 H4− C−
H
n
OR displayed formula
NH-CO linkage [1]
correct structure within brackets [1]
continuation bonds and n [1]
(ii)water [1]
6 (a)formed from monomer with double bond
breaking then linking together [1]
no other molecule formed [1]
−
−
−
−
C=C
H Cl [1]
(ii)1,1-dichloroethene ALLOW:
dichloroethene [1]
(c) (i)poly(tetrafluoroethene)
(ii)―CF2―CF2―CF2―CF2―CF2―CF2― or
displayed formula
3 CF2 units or 6 CF2 units [1]
continuation bonds at each end [1]
(d)poisonous fumes released / acidic fumes
released [1]
7 (a)ester [1]
(b)PET / terylene [1]
―COOH [1] HO― ―OH
(c) (i)HOOC―
[1]
(ii)condensation [1] polymer formed
from two types of monomer [1] small
molecule eliminated [1]
8 (a)amino acids [1]
O
(b) (i)
− C − N−
−
−
−C − C −
H Cl
(b) (i)
=
−
−
three CH(CH3)―CH2 units [2]
if 2 marks not scored 1 mark for a chain of
6 carbon atoms [1]
continuation bonds [1]
(c)
CH3 H
H
(ii) nylon [1]
(c) —NH―CO―CH2―NH―CO―CH2―NH―CO―
CH2― or displayed formula
repeat units [1] all NH―CO bonds in same
direction [1]
continuation bonds at each end [1]
41