1.1.2 Moles and equations
This Powerpoint contains the questions
and answers for the activities 1-20
1. Convert the following masses as
specified.
i)0.357 kg into g;
ii)5.46 tonnes into g;
iii)89000000 g into tonnes;
iv)1.34 x 109 g into kg;
v)1.43 x 10-7 tonnes into g.
1. Convert the following masses as
specified- Answers
i)0.357 kg into g;
ii)5.46 tonnes into g;
iii)89000000 g into tonnes;
iv)1.34 x 109 g into kg;
v)1.43 x 10-7 tonnes into g.
357g
5 460 000g
89 tonnes
1340000kg
0.143g
2. Conversion of volumes into
different units
i)0.357 dm3 into cm3;
ii)6.35 m3 into cm3;
iii)51000000 cm3 into m3;
iv)7.48 x 10-7 m3 into cm3.
2. Conversion of volumes into
different units
i)0.357 dm3 into cm3;
ii)6.35 m3 into cm3;
iii)51000000 cm3 into m3;
iv)7.48 x 10-7 m3 into cm3.
357cm3
6350000cm3
51m3
0.748cm3
3. Using significant figures
• Answering to 3 significant figures
• Write the following numbers to 3 significant figures
i) 0.10752
ii) 58.942
iii) 0.0001178
iv) 23467889
v) 4.522 x 10-4
3. Using significant figures
i) 0.10752
ii) 58.942
iii) 0.0001178
iv) 23467889
v) 4.522 x 10-4
0.108
58.9
0.000118
23500000
4.52 x 10-4
5. Categorizing materials as
substances or mixtures
Underline the materials from the list below
which you would describe as substances
(Hint; substances are those which are not
mixtures).
Sugar, water, air, seawater , wood, sodium
chloride, sulphur dioxide, chlorine,
calcium, lemon juice, bromine, plastic
6. Converting numbers of particles
into moles
Convert the following numbers of particles
into moles
i)12.04 x 1023 electrons;
ii) 1.35 x 1024 sodium ions
6. Converting numbers of particles
into moles
i) 12.04 x 1023 electrons;
ii) 1.35 x 1024 sodium ions;
2 moles
2.2 moles
7. Converting moles into numbers
of particles
i) How many particles are present in 0.0032 moles of
electrons?
ii) How many atoms are present in 2.4 moles of
magnesium?
7. Converting moles into numbers
of particles
i) How many particles are present in 0.0032 moles
of electrons? 1.93x1021
ii) How many atoms are present in 2.4 moles of
magnesium? 1.44 x1024
9. Finding the molar masses of
simple compounds
Calculate the molar mass of the following compounds from
their formulae
i) CO2
ii) H2O
iii) Ca(OH)2
iv) NH4NO3
9. Finding the molar masses of
simple compounds
i) CO2
44g
ii) H2O
18g
iii) Ca(OH)2
74.1g
iv) NH4NO3
80g
10. Calculating the percentage by
mass of an element in a compound
Calculate the percentage by mass of the named
element in each of the compounds listed.
i) Aluminium in AlCl3
ii) Hydrogen in (NH4)3PO4
10. Calculating the percentage by
mass of an element in a compound
i) Aluminium in AlCl3
Mr 133.5
20.2%
ii) Hydrogen in (NH4)3PO4
Mr 149.1
8.05%
12. Deducing the molecular formula
from empirical formula and molar mass
i) An oxide of hydrogen with molar mass 34 has an
empirical formula OH. What is the molecular formula?
12. Deducing the molecular formula
from empirical formula and molar mass
i) An oxide of hydrogen with molar mass 34 has an
empirical formula OH. What is the molecular
formula? H2O2
13. Calculating the empirical formula from
percentage composition
Work out the empirical formulae for the
following compounds
i) N 87.5%
H 12.5%
13. Calculating the empirical formula from
percentage composition
i) N 87.5%
H 12.5%
NH2
14. Calculating the empirical formula
from the percentage of one reactant
Work out the empirical formulae for the following
compounds
i) A chloride of chromium which contains 73.3%
chlorine;
ii) A chloride of copper which contains 47.2%
copper.
14. Calculating the empirical formula
from the percentage of one reactant
i) A chloride of chromium which contains
73.3% chlorine; CrCl4
ii) A chloride of copper which contains
47.2% copper.
CuCl2
17. Writing symbol equations for
reactions we have studied
Write symbol equations for the following.
i) magnesium
+ copper sulphate
ii) sodium
+ hydrochloric
carbonate
acid
→ copper + magnesium sulphate
→ sodium + water +
chloride
carbon
dioxide
17. Writing symbol equations for
reactions we have studied
i) magnesium + copper sulphate
Mg
+
CuSO4
→
→
ii) sodium
+
carbonate
Na2CO3 +
→ sodium
chloride
→2NaCl
hydrochloric
acid
2HCl
copper + magnesium sulphate
Cu
+
MgSO4
+ water + carbon
dioxide
+ H2O + CO2
18. Writing symbol equations for reactions
with reactants or products stated
Write symbol equations for the following reactions.
i) Burning propane (C3H8) to produce carbon dioxide and water.
ii) The formation of calcium carbonate (CaCO3) from calcium oxide and
carbon dioxide.
iii) Production of hydrogen sulphide (H2S) from its elements.
iv) Production of sulphur dioxide from its elements.
v) The reaction of silicon tetrachloride (SiCl4) with water to produce
silicon dioxide and another product.
18. Writing symbol equations for reactions
with reactants or products stated
i)
ii)
Burning propane (C3H8) to produce carbon dioxide and
water.
C3H8 + 5O2 → 3CO2 + 4H2O
d) The formation of calcium carbonate (CaCO3) from
calcium oxide and carbon dioxide.
CaO + CO2 → CaCO3
(continued)
iii) Production of hydrogen sulphide (H2S) from its
elements.
H2 + S → H2S
iv) Production of sulphur dioxide from its elements.
S + O2 → SO2
v) The reaction of silicon tetrachloride (SiCl4) with water to
produce silicon dioxide and another product.
SiCl4 + 2H2O → SiO2 + 4HCl
19. Reacting masses: using
moles=mass/Mr
How many moles are in the following substances? (answer
to 3 sf)
i) 1.6g of methane gas;
ii) 30.4g of sodium;
iii) 90.2g of aluminium sulphide;
iv) 1.7g of ammonium oxide;
____
____
____
____
19. Reacting masses: using
moles=mass/Mr
i) 1.60g of methane gas;
ii) 30.4g of sodium;
iii) 90.2g of aluminium sulphide;
iv) 1.7g of ammonium oxide;
0.100
1.32
0.600
0.0327
20. Calculating the mass from the
number of moles
Work out the masses of the following quantities.
i) 5 moles of calcium
ii) 0.5 moles of water;
iii) 1.2 moles of magnesium chloride;
iv) 7.86 x 10-6 moles of hydrogen chloride.
20. Calculating the mass from the
number of moles
i) 5 moles of calcium
200.5g
ii) 0.5 moles of water;
9.0g
iii) 1.2 moles of magnesium chloride;
114.36g
iv) 7.86 x 10-6 moles of hydrogen chloride. 0.000287g
21.
i) How many moles of iron will react with chlorine to form
0.47 mole of iron (III) chloride?
2Fe(s)
+
3Cl2(g)
→
2FeCl3(s)
Answers
i) How many moles of iron will react with chlorine to form
0.47 mole of iron (III) chloride? 0.47
2Fe(s)
+
3Cl2(g)
→
2FeCl3(s)
21.
ii) How many moles of calcium chloride could you obtain by
action of excess acid on 5.43 moles of calcium
carbonate?
CaCO3(s)
+
2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)
iii) How many moles of sodium chloride can be produced
by reacting 0.5 moles of chlorine?
2Na(s)
+
Cl2(g)
→
2NaCl(s)
Answers
ii) How many moles of calcium chloride
could you obtain by action of excess acid
on 5.43 moles of calcium carbonate? 5.43
CaCO3(s)+ 2HCl(aq)→CaCl2(aq)+ CO2(g)+ H2O(l)
iii) How many moles of sodium chloride can
be produced by reacting 0.5 moles of
chlorine? 1
2Na(s)
+
Cl2(g)
→ 2NaCl(s)
21.
iv)How many moles of sodium carbonate can be obtained by heating 0.5 moles
of sodium hydrogen carbonate?
2NaHCO3 (s)
→
Na2CO3
+ CO2(g) + H2O(l)
v) How many moles of sodium carbonate can be obtained by heating 1.3 moles
of sodium hydrogen carbonate?
2NaHCO3 (s)
→
Na2CO3
+ CO2(g) + H2O(l)
vi) How many moles of calcium phosphate are needed to produce 0.326 moles
of P4 by the reaction below (answer to 3 sf)?
2Ca3(PO4)2
+ 6SiO2 + 5C
→
P4
+ 6CaSiO3
+5CO2
Answers
iv) How many moles of sodium carbonate can be obtained by heating
0.5 moles of sodium hydrogen carbonate? 0.25
v) How many moles of sodium carbonate can be obtained by heating
1.3 moles of sodium hydrogen carbonate? 0.65
2NaHCO3 (s) →
Na2CO3
+ CO2(g)
+ H2O(l)
vi) How many moles of calcium phosphate are needed to produce
0.326 moles of P4 by the reaction below? 0.652
2Ca3(PO4)2+ 6SiO2
+ 5C→ P4
+ 6CaSiO3
+5CO2
21.
vii)How many moles of aluminium chloride can be made
from 1 mole of chlorine (answer to 3 sf)?
2Al(s)
+
3Cl2(g)
→
2AlCl3(s)
viii) How many moles of aluminium chloride can be made
from 0.72 moles of chlorine (answer to 3 sf)?
2Al(s)
+
3Cl2(g)
→
2AlCl3(s)
21. ANSWERS
vii)How many moles of aluminium chloride can be made
from 1 mole of chlorine (answer to 3 sf)? 0.67
2Al(s)
+
3Cl2(g)
→
2AlCl3(s)
viii) How many moles of aluminium chloride can be made
from 0.72 moles of chlorine (answer to 3 sf)? 0.48
2Al(s)
+
3Cl2(g)
→
2AlCl3(s)
22.
i) Calculate the mass of lead (II) nitrate needed to produce
22.3g of lead (II) oxide in the reaction shown below.
2Pb(NO3)2 (s)
→
2PbO (s) + 4NO2(g) + O2(g)
22. Answers
i) Calculate the mass of lead (II) nitrate needed to produce
22.3g of lead (II) oxide in the reaction shown below.
33.12g
2Pb(NO3)2 (s)
→
2PbO (s) + 4NO2(g) + O2(g)
22.
ii) Calculate the mass of calcium chloride you could obtain
by action of excess acid on 15g of calcium carbonate.
CaCO3(s)
+
2HCl(aq)
→
CaCl2(aq) + CO2(g) +
H2O(l)
)
iii) Calculate the mass of iron oxide made from 14g of iron.
3Fe(s)
+
2O2(g)
→
Fe3O4(s)
22. Answers
ii) Calculate the mass of calcium chloride you could obtain
by action of excess acid on 15g of calcium carbonate.
16.64g
CaCO3(s)
+
2HCl(aq)
→
CaCl2(aq) + CO2(g) +
H2O(l)
iii) Calculate the mass of iron oxide made from 14g of iron.
19.3g
3Fe(s)
+
2O2(g)
→
Fe3O4(s)
22.
iv) Find the maximum mass of sodium carbonate
which can be obtained by heating 100g of
sodium hydrogen carbonate.
2NaHCO3 (s)
→
Na2CO3+ CO2(g) + H2O(l)
22. Answers
iv) Find the maximum mass of sodium carbonate
which can be obtained by heating 100g of
sodium hydrogen carbonate. 63.1g
2NaHCO3 (s)
→
Na2CO3
+ CO2(g)
+ H2O(l)
23. Calculating the number of
moles from gas volume
i) 48000 cm3 of methane;
ii) 4000 cm3 of nitrogen;
iii) 18dm3 of fluorine;
iv) 0.325 cm3 of helium;
Answers
i) 48000 cm3 of methane; 2 moles
ii) 4000 cm3 of nitrogen; 0.167 moles
iii) 18dm3 of fluorine; 0.75 moles
iv) 0.325 cm3 of helium; 1.35 x 10-5moles
24.
i) 3 moles of methane;
ii) 1.4 moles of hydrogen;
iii) 7.6g of fluorine;
iv) 13 tonnes of ethane.
Answers
i) 3 moles of methane; 72dm3
ii) 1.4 moles of hydrogen; 33.6dm3
iii) 7.6g of fluorine; 4.8dm3
iv) 13 tonnes of ethane. 1.04 x 107 dm3
Activity 25a
Calculating the mass or volume of a product from
the mass or volume of a reactant
i) What volume of ethyne (C2H2) can be produced from 10g
of calcium carbide by the following reaction?
CaC2(s) + 2H2O(l)→ Ca(OH)2(aq) + C2H2(g)
Activity 25a Continued
Calculating the mass or volume of a product from the mass
or volume of a reactant
ii) What mass of PbO2 is required to produce
40dm3 of oxygen by the equation shown
below?
2PbO2(s)) → 2PbO(s) + O2(g)
iii) What mass of potassium chlorate (v) must
be heated to give 1.00dm3 of oxygen in the
following reaction?
2KClO3(s)) → 2KCl(s) + 3O2(g)
Activity 25a Continued
Calculating the mass or volume of a product from the mass
or volume of a reactant
iv) What volume of chlorine is produced from
340g of Pb3O4?
Pb3O4 (s) + 8HCl(l) → 3PbCl2(s)+Cl2(g)+ 4H2O(l)
Activity 25a Continued
Calculating the mass or volume of a product from
the mass or volume of a reactant
v) Calculate the volume of carbon dioxide
produced when 5g of calcium carbonate is
treated with excess hydrochloric acid.
Activity 25a ANSWERS
i) 3.74dm3 (3740cm3)
ii) 3.41g
iii) 11.9dm3
iv) 1.2 dm3 (1200cm3)
Activity 26
Calculate the number of moles of dissolved
substance in the following quantities of solutions
i) 500cm3 of 1moldm-3 NaOH;
ii) 31.55cm3 of 0.01moldm-3 HCl;
iii) 28.40cm3 of 0.02moldm-3 NaOH.
Exercise 26: Answers
i) 0.5 moles
ii) 0.000316 moles (3.16x10-4)
iii) 0.000568 moles (5.68x10-4)
Activity 27
Calculating the concentration from number of moles of
dissolved substance and solution volume
i) 0.2 moles of NaOH in 1000cm3 of solution;
ii) 0.2 moles of NaOH in 52cm3 of solution;
iii) 0.137 moles of HCl in 32.55cm3 of
solution;
Exercise 27: Answers
i) 0.2 mol dm-3
ii) 3.85 mol dm-3
iii) 4.21 mol dm-3
Activity 28
Calculating the solution volume from number of moles of
dissolved substance and concentration
i) 0.43 moles of HCl; the concentration of HCl is 1moldm-3;
ii) 5.1 moles of NaOH; the concentration of NaOH is
1moldm-3;
iii) 0.0321 moles of HCl; the concentration of HCl is
0.02moldm-3;
Exercise 28: Answers
i) 430 cm3
ii) 5100 cm3
iii) 1605 cm3
Activity 29
Calculating the concentration of a reactant from the
concentration and volume of the other reactant
i) In a titration to calculate the concentration of some
sodium hydroxide solution, a student took 20cm3 of the
sodium hydroxide and used 15 cm3 of hydrochloric acid
of concentration 0.50 moldm-3 to neutralise it. Calculate
the concentration of the sodium hydroxide.
NaOH(aq)+ HCl(aq) →
NaCl(aq)
+
H2O(l)
Activity 29
ii) If 25.0cm3 of a solution of sodium hydroxide are
neutralised by 27.5 cm3 of sulphuric acid of
concentration 0.250 moldm-3, what is the concentration
of the sodium hydroxide?
2NaOH(aq)+ H2SO4(aq) →Na2SO4 (aq) + 2H2O(l)
Exercise 29: Answers
i) 0.374 mol dm-3
ii) 0.55 mol dm-3
Activity 30. Calculating reacting volumes, given the
reaction equation and n=cv/1000 data
i) Predict the volume of hydrochloric acid
(0.2moldm-3) needed to neutralise 250cm3
0.2moldm-3 sodium carbonate.
Na2CO3 (aq) + 2HCl(aq) → 2NaCl(aq) + CO2(g) + H2O(l)
Activity 30. Calculating reacting volumes, given the
reaction equation and n=cv/1000 data
ii) Predict the volume of phosphoric acid
(0.1moldm-3) needed to neutralise 30cm3
0.1moldm-3 sodium hydroxide.
3NaOH(aq) + H3PO4(aq) →Na3PO4 (aq) + 3H2O(l)
Activity 30. Calculating reacting volumes, given the
reaction equation and n=cv/1000 data
iii) Predict the volume of sulphuric acid (0.1moldm3) needed to neutralise 21.25cm3 0.25moldm-3
sodium hydroxide.
2NaOH(aq) + H2SO4(aq) →Na2SO4 (aq) + 2H2O(l)
Exercise 30: Answers
i) 500 cm3
ii) 10 cm3
iii)26.6 cm3
32. Deducing the stoichiometric relationship
from given masses and gas volumes
i) When heated, 0.080g of sulphur reacted with 60cm3
oxygen to produce an oxide of sulphur. Deduce the
formula of the oxide.
Exercise 32: Answers
a) SO2