National 5 Unit 1
Chemical Changes
and Structure
Check Tests
Check Test 1.1
Decide whether each of the following:
A – IS a chemical reaction
B – IS NOT a chemical reaction
1. Mixing two solutions to produce a
gas
13. Mixing two solutions forming a
yellow solid
2. Boiling water in a kettle
14. Mixing sand and water
3. Gas fizzing when you open a bottle
of lemonade
15. Petrol burning in a car engine
4. Mixing salt and pepper
16. Dissolving sugar in tea
5. Breaking up a lump of chalk to make
a powder
17. Milk being produced in a cow
6. Mould forming on stale bread
18. Adding milk to coffee
7. A gas explosion
19. A leaf growing on a tree
8. Breaking glass
20. Burning paper
9. Separating a solid from a liquid
21. Food digesting in the stomach
10. Melting a plastic
22. Making toast from bread
11. Using a magnet to separate iron
from a mixture
23. New skin forming over a cut
12. A pea forming in a pod
24. Slicing bread
Page 1
Check Test 1.2
1. You are making roast potatoes, what two things could you do to make them cook
faster?
2. In gas cookers it is often found that the metal first rusts nearest the burners. Explain.
3. If 1g of a catalyst is used in an experiment, what mass will be left when the reaction
is finished?
4. Sea shells (mainly calcium carbonate, like marble) react with vinegar (an acid) to
produce carbon dioxide gas. What would be the effect on the speed of reaction if
a.
b.
c.
d.
e.
f.
the shells were crumbled
water was added to the vinegar
the vinegar was heated
a catalyst was used
the experiment was carried out in a refrigerator
the ordinary vinegar (5% acid) was replaced by another vinegar (7% acid).
Page 2
Check Test 1.3
1. A group of students were investigating the
reaction between chalk and acid.
They all used 100cm3 of the same hydrochloric
acid, in each reaction all of their chalk was
used up.
They each measured the rate at which the mass
of the mixture changed
One student used 5g of chalk lumps and
obtained the graph opposite.
Copy the graph and add to it the curves you would expect for the experiments
carried out by two other students, the details of which are:
a. Student 2 used 5g of chalk lumps but ground them to a fine powder.
b. Student 3 used 2.5g of chalk lumps the same size as the lumps used by
student 1.
2. A group of pupils wanted to investigate the effect of changing the acid concentration
in the reaction rate with magnesium metal by timing how long it takes for the
magnesium to disappear. Describe three variables that need to be kept constant in
the investigation.
Questions 3 and 4 refer to this graph.
volume of
hydrogen
(cm3)
50
40
30
20
10
1
2
3
4
5
6
time (minutes)
3. What is the average rate of reaction
during the time interval 0 – 1 minutes?
A
B
C
D
4. What is the average rate of reaction
during the time interval 1 – 3 minutes?
15 cm3 / min
25 cm3 / min
35 cm3 / min
20 cm3 / min
A
B
C
D
Page 3
17 cm3 / min
27 cm3 / min
37 cm3 / min
30 cm3 / min
Questions 5 and 6 refer to the graph shown, which was plotted from the reaction
between marble and hydrochloric acid.
volume of
carbon
dioxide
(cm3)
5. The rate of reaction at point X is
best described as
A
B
C
D
Y
X
time
(minutes)
6. What
conclusion can be made from the rate
shown at point Y
very fast
medium
quite slow
almost stopped
A
B
C
D
Page 4
All the acid has been used up.
All the marble has been used up.
There is no reaction taking place.
All the reactants have been used up.
Check Test 1.4
1. A student is given a sample of an unknown element.
Describe how they could identify whether the element is a metal or a non-metal.
2. The table lists some substances.
A
D
Bromine
Oxygen
B
E
Methane
Uranium
C
Mercury
F
Water
Which box (or boxes)
a. is not an element?
b. is an element which is a liquid at room temperature?
c. is an element which is a gas at room temperature?
3. Present the following information in the form of a table with the headings
Alkali Metals and Noble Gases.
React violently with water, low boiling points, present in the air, produce coloured
flames, have a full outer electron shell, very unreactive chemically, can conduct
electricity, contain one outer electron.
4. Copy and complete the following sentences into your jotter.
a. A column of elements is called a ____________________.
b. A row of elements is called a _______________.
5. Name the family of
a. Unreactive elements
b. Very reactive metallic elements.
c. Reactive non-metallic elements.
Page 5
Check Test 1.5
1. What is the name given to the core at the centre of an atom?
2. Consider this list of elements:
magnesium, carbon, oxygen, chlorine, sodium, nitrogen
a. Which element has an atomic number of 17?
b. Which element has 11 electrons in each of its atoms?
c. Which element has 12 protons in each of its atoms?
3. Copy and complete the following table.
Subatomic Particle
Mass
Charge
Location
electron
proton
neutron
4. An atom has a mass of 7. It contains 4 neutrons. How many protons does this atom
contain?
5. Atom A has mass number 239 and atomic number 93.
Atom B has a mass number 239 and atomic number 94.
a. How many protons has A?
b. How many neutrons has B?
c. Are atoms A and B of the same element? Explain your answer.
6. Which box (or boxes) in the grid below shows:
a. a particle found outside the nucleus of an atom
b. shows the information about a carbon atom
c. an isotope of an atom with 7 protons, 8 neutrons and 7 electrons?
A atom contains 6
B
C
protons, 7 neutrons
electron
and 6 electrons
D
E atom contains 7
F
proton
protons, 7 neutrons
and 7 electrons
Page 6
atom contains 7
protons, 8 neutrons
& 10 electrons
neutron
Check Test 1.6
1. In nuclide notation what is the name given to
X
Y
Z
a. The number in position X?
b. The number in position Y?
c. The letter(s) in position Z?
2. Write the nuclide notation an atom with:
a. atomic number 12 and mass number 24
b. atomic number 17 and mass number 35
c. atomic number 5 and mass number 11
d. 7 protons and mass number 7
e. mass number 19 and 10 neutrons
f. 15 protons and 16 neutrons.
79
35
3. Bromine exists as two types of atom;
Br
Br
81
35
and
What name is given to these types of atom of an element?
4. Copy and complete this table.
Symbol
16
8
O
39
19
K
64
Atomic
number
Mass
Number
Number of
protons
Number of
neutrons
35
46
Number of
electrons
Cu
238
U
16
10
Co
12
68
5. Why is the Relative Atomic Mass often not a whole number?
6. Which of the two bromine atoms in Q3 is more abundant?
Page 7
16
Check Test 1.7
1. An atom has 14 electrons. Draw a target diagram of how these are arranged and
underneath it write down the electron arrangement.
2. Draw target diagrams to show how the electrons are arranged in the following
elements:
a. boron
b. magnesium
c. O
d. C
e. atomic number 10
f. atomic number 19
3. Which elements have the following electron arrangements:
a. 2,8,8,2
b. 2,8,5
c. 2,7
d. 2,8,8?
4. Copy and complete the following table.
Symbol
Atomic
number
Mass
Number
Number of
protons
Number of
neutrons
Electron
arrangement
Mg
12
25
12
13
2,8,2
4
2,1
18
2,8,7
10
2,7
18
8
41
20
Page 8
Check Test 1.8
1. What name is given to the type of particle formed when an atom gains or loses
electron(s)?
2. What type of element tends to
a. lose electrons when it reacts?
b. gain electrons when it reacts?
3. What charge will an ion has if it is formed when an atom
a. loses 3 electrons?
b. gains 2 electrons?
4. Why do noble gases neither gain nor lose electrons?
5. Write the symbols and electron arrangements for:a. a magnesium ion
b. the ion formed by sulphur atoms.
c. the ion formed by nitrogen atoms.
d. a potassium ion
e. an aluminium ion
f. the ion formed by fluorine atoms.
g. What can you say about the electron arrangements of the ions in (a), (c),
(e) and (f)?
6. Which box (or boxes) in the grid below shows an:a. atom or ion which contains 10 electrons
b. atom or ion which has 8 neutrons
c. ion which has 16 protons
d. ion which has no electrons?
A
D
16
8
O 2
B
33
16
S 2
E
14
6
20
10
C
Ne
C
F
18
8
3
1
O
H
7. What two things link every element in a group of the periodic table?
Page 9
Check Test 1.9
1. Name the elements present in the following compounds and give their chemical
symbol.
a. sodium bromide
b. lithium phosphide
c. iron carbide
d. potassium fluoride
e. magnesium nitrate
f. calcium carbonate
g. cobalt chlorate
h. lead sulphate
2. Name the compounds formed from the following elements
a. tin and hydrogen
b. calcium and carbon
c. copper and iodine
d. silver and oxygen
e. iron, carbon and oxygen
f. zinc, phosphorous and oxygen
g. tin, sulphur and oxygen
h. barium, nitrogen and oxygen
3. Which box (or boxes) in the grid below shows an element contained in
a. sodium carbide
b. calcium sulphate
c. potassium sulphite
d. potassium carbonate
e. sodium oxide
A
D
calcium
carbon
B
E
sodium
oxygen
C
F
sulphur
potassium
4. Write a word equation for the formation of a compound from the following
elements.
a. copper and chlorine
b. sodium and bromine
c. nitrogen and hydrogen
d. magnesium and phosphorus
Page 10
Check Test 1.10
1. Write the formula for the following compounds.
a. hydrogen chloride
b. phosphorus oxide
c. silicon phosphide
d. carbon hydride
e. phosphorous sulphide
f. carbon nitride
2. Name the following compounds from their formulae.
a. NH3
b. SiH4
c. HI
d. NaBr
3. Write the formula for these compounds
a. sulphur trioxide
c. carbon dioxide
b. nitrogen monoxide
d. dinitrogen tetraoxide
4. Which box (or boxes) in the grid below shows
a. the valency of the group six elements?
b. an element with a valency of one?
c. an element with a valency of three?
d. the valency of helium?
A
D
two
zero
B
E
hydrogen
phosphorus
C
F
nitrogen
one
5. Which box (or boxes) in the grid below shows
a. a non-metal with three unpaired outer electrons?
b. a non-metal with no unpaired outer electrons?
c. an element with a valency of two?
d. an element which has electrons in the fourth electron shell?
A
D
chlorine
nitrogen
B
E
oxygen
sulphur
C
F
calcium
argon
6. A compound of an unknown element, X, and hydrogen contains three hydrogen
atoms for every atom of X.
a. What is the valency of unknown element X?
b. In which group(s) in the periodic table could X be found?
c. Suggest a metal that X could be and name the compound.
d. Suggest a non-metal that X could be and write a word equation for its
formation.
Page 11
Check Test 1.11
1. Write the formula and state the valency of the following group ions.
a. sulphate
b. nitrate
c. hydroxide
d. carbonate
e. sulphite
f. phosphate
2. Write the formula for the following compounds
a. magnesium sulphate
b. sodium hydroxide
c. calcium sulphite
d. aluminium phosphate
e. potassium carbonate
f. lithium sulphate
g. ammonium hydroxide
h. potassium nitrate
3. Write the formula for the following compounds
a. copper(I) sulphate
b. zinc(II) hydroxide
c. silver(I) nitrate
d. cobalt(II) chloride
4. Name the following compounds from their formula
a. NaNO3
b. Al2(SO4)3
c. Li3PO4
d. CaSO3
5. Name the following compounds from their formula, including roman numerals
a. CuO
b. Cu2O
c. FeCl3
d. ZnSO4
e. AgNO3
f. Ni(OH)2
Page 12
Check Test 1.12
1. State the names and formulae of the seven diatomic elements
2. Draw a diagram showing all outer electrons in a molecule of
a. carbon hydride
b. nitrogen hydride
c. carbon chloride
d. phosphorus fluoride
e. chlorine
f. hydrogen bromide
3. What is a covalent bond?
4. Describe how a covalent bond holds two atoms together.
5. Compound X and Y both contain covalent bonds. X has a melting point of -57 ˚C
and Y has a melting point of 1713 ˚C. Explain which type of covalent structure
compound X and Y have.
6. What is an ionic bond?
7. What is the name given to the ordered arrangement of ions in a solid?
8. Why can ionic compounds such as lithium chloride conduct electricity when in the
liquid state?
9. Why can covalent compounds such as ethanol not conduct electricity in any state?
10. Copy and complete the following table
Conduction
Substance
solid
solution
lithium chloride
ethanol
no
no
calcium nitrate
no
yes
candle wax
Ionic or
Covalent
ionic
covalent
11. A group of pupils are given two compounds and told that one is covalent and one
is ionic. Describe a test the pupils could carry out to identify each.
12. What is the definition of an electrical current?
Page 13
Check Test 1.13
1. State the chemical formula for the following compounds
a. sodium bromide
b. lithium phosphide
c. iron(II) sulphate
d. potassium oxide
e. barium nitrate
f. calcium carbonate
2. Mark your answers to question 1, then, when correct, give the ionic formula for
each compound.
Check Test 1.14
1. Write a formula equation for the formation of a compound from the following
elements.
a. aluminium and chlorine
b. sodium and bromine
c. nitrogen and hydrogen
d. magnesium and phosphorus
2. Write the formula with the correct state symbol for the following
a. molten aluminium oxide
b. sodium bromide solution
c. steam
d. magnesium carbonate crystals
e. lithium hydroxide solution
f. liquid water
3. Write a formula equation with state symbols for the following reactions.
a. Sodium metal reacts with water to form sodium hydroxide solution and
hydrogen gas.
b. Magnesium metal burns in oxygen gas to form a white powder called
magnesium oxide.
Page 14
Check Test 1.15
1. Copy and balance the following
a. H2
+
F2
→
b. C
+
O2
→
c. C
+
Cl2
→
d. C2H6 +
O2
→
equations.
HF
CO
CCl4
CO2 +
H2O
2. Change the following word equations into balanced formulae equations
a. nitrogen hydride
+
oxygen
→
nitrogen
+
water
b. nitrogen monoxide +
oxygen
→
nitrogen dioxide
3. Write a balanced formula equation for the following reaction, including state
symbols.
When petrol, C8H18, burns in a car engine, carbon dioxide gas and water vapour
are emitted from the exhaust.
Check Test 1.16
1. State the relative atomic mass of the following elements.
a. lithium
b. sulphur
c. sodium
d. iron
e. gold
f. copper
g. chlorine
h. argon
2. Why is the relative atomic mass of chlorine not a whole number?
3. State another name for the mass of one mole of a substance.
4. Calculate the gram formula mass of the following substances
a. nitrogen N2
b. nitrogen dioxide NO2
c. sodium nitrate NaNO3
d. silicon tetrachloride SiCl4
e. copper(II) chloride CuCl2
f. calcium hydroxide Ca(OH)2
g. lead(IV) oxide PbO2
h. aluminium bromide AlBr3
5. Write the formula of the following compounds and calculate the mass of one
mole.
a. sodium chloride
b. aluminium fluoride
c. calcium sulphate
d. hydrogen chloride
e. sodium hydroxide
f. nitrogen tribromide
g. copper(II) carbonate
h. ammonium nitrate
Check Test 1.17
Page 15
1. Calculate the mass of the following
a. 1 mole of chlorine Cl2
c. 10 moles of methane CH4
e. 0.5 moles of ammonia NH3
b. 2 moles of sulphur dioxide SO2
d. 1.5 moles of water H2O
f. 3.7 moles of sodium carbonate Na2CO3
2. How many grams is contained in the following
a. 1 mole of copper
b. 4 moles of argon
c. 2 moles of oxygen
d. 1.5 moles of carbon dioxide
e. 10 moles of calcium carbonate
f. 3 moles of sodium chloride
g. 0.5 moles of lithium fluoride
h. 0.2 moles of ethane
i. 0.25 moles of copper(II) oxide
j. 2 moles of ammonium sulphate
3. How many moles are contained in
a. 56 g of nitrogen
c. 400 g of copper(II) oxide
e. 30 g of aluminium sulphide
g. 321 g of iron(III) hydroxide
i. 145 g of methane
b.
d.
f.
h.
j.
85 g of lithium chloride
117 g of sodium sulphide
84 g of magnesium carbonate
2 kg of hydrogen
5.6 g of calcium oxide.
Check Test 1.18
Page 16
1. Calculate the concentration of the following solutions.
a. 2 moles of sodium chloride dissolved in 1 litre of water.
b. 1 mole of calcium nitrate dissolved in 500 cm3 of water.
c. 0.5 moles of sugar dissolved in 200 cm3 of water.
d. 1.5 moles of copper sulphate dissolved in 250 cm3 of water.
2. Calculate the number of moles of solute in the following solutions
a. 2 litres of 2 moll-1 solution
b. 500 cm3 of 0.5 moll-1 solution
c. 250 cm3 of 0.1 moll-1 solution
d. 100 cm3 of 4 moll-1 solution
3. What is the concentration of a solution obtained by dissolving
a. 40 g of sodium hydroxide in 1 litre of water?
b. 585 g of sodium chloride in 5 litres of water?
c. 2.8 g of potassium hydroxide in 150 cm3 of water?
d. 8.5 g of sodium nitrate in 50 cm3 of water?
4. Calculate the mass of
a. potassium hydroxide needed to make 500 cm3 of 1 moll-1 solution.
b. copper (II) sulphate needed to make 250cm3 of 0.1 mol-1 solution.
c. potassium chloride is dissolved in 100 cm3 of water to make a 1.5 moll-1
solution.
5. Calculate the volume of solvent required to make
a. 0.25 moll-1 solution containing 58.5 g of sodium chloride.
b. 0.1 moll-1 solution containing 1.06 g of sodium carbonate.
c. 0.4 moll-1 solution containing 40 g of sodium hydroxide.
Check Test 1.19
1. Which box (or boxes) in the grid below shows:
Page 17
a.
b.
c.
d.
A
D
a colour produced when pH indicator is added to an acid?
a pH number of an alkaline solution?
the colour when sodium hydroxide is added to pH paper?
the pH number of pure water?
orange
red
B
E
fourteen
eight
C
F
blue
seven
2. State what happens to the pH when water is added to
a. an acidic solution
b. an alkaline solution.
3. State whether each of the following statements is true or false.
a. All alkaline solutions contain the oxide ion.
b. A vinegar solution should have a pH of 9.
c. Neutral solutions must have a pH equal to 7.
d. pH numbers are always whole numbers between 0 and 14.
4. Copy and complete the following sentences.
A substance which can neutralise and acid is called a __________. They can be
metal _______________, metal ________________ or metal ________________.
5. Which box (or boxes) in the grid below contains:
a. an alkali?
b. an insoluble base?
A
B
ammonium
sodium
hydroxide
chloride
D
copper(II)
oxide
E
sodium
hydroxide
C
calcium
carbonate
F
silver(I)
nitrate
6. Copy and complete the following word equations
a. sulphuric acid
+
sodium hydroxide
b. hydrochloric acid
+
potassium hydroxide
→
→
7. Rewrite each of the two equations in Q6 as a balanced formula equation.
Check Test 1.20
1. Which ion is present in a greater concentration in
a. an acid solution than in pure water?
Page 18
b. an alkaline solution than in pure water?
2. Which box (or boxes) in the grid below contains compounds which are:
a. Insoluble hydroxides?
b. Insoluble oxides?
c. Compounds of alkali metals?
d. Alkaline when dissolved in water?
A
B
C
magnesium
copper(II)
potassium
hydroxide
oxide
hydroxide
D
Zinc(II)
oxide
E
F
lead(II)
oxide
sodium
oxide
3. Explain why pure water can conduct electricity.
4. During the electrolysis of an acid ________________ gas is formed at the
_________________ electrode. This proves that all acids contain the _____________
ion which has the formula ______.
5. State the chemical formula for
a. Sulphuric acid
c. Hydrochloric acid
e. Calcium hydroxide
b. Nitric acid
d. Sodium hydroxide
f. Aluminium hydroxide
6. Which of the chemicals listed in Q5, when added to water, would have no effect on
its pH? Explain your answer.
Page 19