Topic 1 Quantitative Chemistry
Moles, Avagadro's Constant, Formulas and Equations
1.1
1. The number of moles in 500 g of water is approximately:
A.
B.
C.
D.
28
9000
1x10​25
3x10​26
2. What is the empirical formula of a compound containing 85.7 % by mass of carbon and 14.3 % by
mass of hydrogen?
A.
B.
C.
D.
CH
CH​2
CH​4
C​2​H​5
3. An oxide of metal M contains 40 % by mass of oxygen. The metal has a relative atomic mass of 24.
What is the empirical formula of the oxide?
A.
B.
C.
D.
M​2​O
M​2​O
MO​2
MO
4. How many molecules are present in a drop of water of mass 9.00xl0-​2​g?
A.
B.
C.
D.
3.01x10​21
3.01 x10​22
9.75x10​23
1.20x10​26
5. 8.0 g of a pure compound contains 3.2 g of sulfur and 4.8 g of oxygen. What is its empirical
formula?
A.
B.
C.
D.
SO
SO​2
SO​3
S​2​O​3
6. How many carbon atoms are present in 0.10 mol of ethanoic acid, CH​3​COOH ?
A.
B.
C.
D.
6.0xl0​22
1.2xl0​23
6.0xl0​23
1.2xl0​24
7. Which of the following contains the greatest number of molecules?
A.
B.
C.
D.
lg of CH​3​Cl
lg of CH​2​Cl​2
lg of CHCl​3
lg of CCl​4
8. Which of the following compounds has/have the empirical formula CH​2​O ?
I.
II.
III.
CH​3​COOH
C​6​H​12​O
C​11​H​22​O​11
A.
B.
C.
D.
II only
III only
I and III only
II and III only
9. What amount (in moles) is present in 2.0 g of sodium hydroxide, NaOH?
A.
B.
C.
D.
0.050
0.10
20
80.
10. How many oxygen atoms are present in 0.0500 mol carbon dioxide?
A.
B.
C.
D.
3.01 x10​22
6.02 x10​22
6.02 x10​23
1.20 x10​24
11. Indigo is a blue dye which contains only carbon, nitrogen, hydrogen and oxygen.
a. 2.036 g of indigo was completely oxidised to produce 5.470 g of carbon dioxide and 0.697 g
of water. Calculate:
i.
the percentage by mass of carbon in indigo;
ii.
the percentage by mass of hydrogen in indigo.
b. If the percentage by mass of nitrogen in the indigo sample is 10.75 %, determine the empirical
formula of indigo.
c. If the molar mass is approximately 260 gmol -1​​ , determine the molecular formula of indigo.
d. Nitrogen also forms an oxide on reaction with oxygen. This oxide contains 25.9 % of nitrogen
and 74.1 % of oxygen by mass. Calculate the empirical formula of this second oxide.
12. An oxide of copper was reduced in a stream of hydrogen as shown below.
After heating, the stream of hydrogen gas was maintained until the apparatus had cooled. The
following results were obtained.
●
●
●
Mass of empty dish = 13.80 g
Mass of dish and contents before heating = 21.75 g
Mass of dish and contents after hearing and leaving to cool = 20.15 g
a. Explain why the stream of hydrogen gas was maintained until the apparatus cooled.
b. Calculate the empirical formula of the oxide of copper using the data above, assuming
complete reduction of the oxide.
c. Write an equation for the reaction that occurred.
d. State ​two ​changes that would be observed inside the tube as it was heated.
Topic 1 Quantitative Chemistry
Mass Relationships in Chemical Reactions
1.2
1. In the decomposition of KClO​3​ 6.30 mol of oxygen was produced:
2KClO​3​ ​→ ​2KCl + 3O​2
How many moles of KCl would be produced?
A.
B.
C.
D.
4.20
6.30
12.6
18.9
2. Formation of polyethene from calcium carbide, CaC​2​, can take place as follows:
CaC​2​ + 2 H​2​O →
​ ​Ca(OH)​2​ + C​2​H​2
C​2​H​2​+H​2​ ​→ ​C2​​ H​4
nC​2​H​4​ ​→ ​H-CH​2​-CH​2​-)​n​What mass of polyethene is obtained from 64 kg of CaC​2​ ?
A.
B.
C.
D.
7kg
14 kg
21 kg
28 kg
3.
N​2​(g) + 3H​2​(g) ​→ ​2NH​3​(g)
56.0 g of N​2​ produces 34.0 g of NH​3​. What is the percentage yield of ammonia?
A.
B.
C.
D.
50
68
74
100
4. What amount of H​2​(g) is produced when 12 g of magnesium reacts completely with dilute
HCl(aq)?
Mg(s) + 2HCl(aq) ​→​ MgCl​2​ (aq) + H​2​ (g)
A. ¼ mol
B. ½ mol
C. 1 mol
D. 2 mol
5. What amount (in moles) of FeS​2​ (s) are required to produce 64 g of SO​2​ (g) according to the
following equation?
4FeS​2​(s) + 110​2​(g)​ ​→​ 2Fe​2​0​3​(s) + 8SO​2​(g)
A. 0.40
B. 0.50
C. 1.0
D. 2.0
6.
PbS(s) + O​2​(g) ->PbO(s) + SO​2​(g)
The reaction of lead (II) sulfide with oxygen at high temperatures is represented by the unbalanced
equation above. What is the sum of the coefficients in the ​balanced ​equation?
A.
B.
C.
D.
4
5
8
9
7. 8.0 g of a pure compound contains 3.2 g of sulfur and 4.8 g of oxygen. What is its empirical
formula?
A.
B.
C.
D.
SO
SO​2
SO​3
S​2​O​3​.
8.
2C​4​H​10​(g)+13O​2​(g) ​→​ 8CO​2​(g)+10H​2​O(l)
How many moles of CO​2​(g) are produced by the complete combustion of 58 g of butane, C​4​H​10​ (g) ?
A.
B.
C.
D.
4
8
12
16
9. Copper can react with nitric acid as follows.
3Cu + _ HNO​3​ ​→ ​_ Cu(NO​3​)​2​ + _ H​2​O + _ NO
What is the coefficient for HNO​3​ when the equation is balanced?
A.
B.
C.
D.
4
6
8
10
10. Consider the equation below.
Fe(s)+S(s) ​→ ​FeS(s)
If 10.0 g of iron is heated with 10.0g of sulfur to form iron (II) sulfide, what is the theoretical yield of
FeS in grams?
A.
B.
C.
D.
10.0 + 10.0
(87.91*10.0) / 55.85
(87.91*10.0) / 32.06
(55.85*10.0) / 32.06
11. 6.0 moles of Fe​2​O​3​ (s) reacts with 9.0 moles of carbon in a blast furnace according to the equation
below.
Fe​2​O​3​(s) + 3C(s) →
​ ​2Fe(s) + 3CO(g)
What is the limiting reagent and hence the theoretical yield of iron?
Limiting Reagent
Theoretical yield of iron
A. Fe​2​O​3
6.0 mol
B. Fe​2​O​3
12.0 mol
C. Carbon
9.0 mol
D. Carbon
6.0 mol
12. Calcium carbonate decomposes on heating as shown below.
CaCO​3​ ​→ ​CaO + CO​2
When 50 g of calcium carbonate are decomposed, 7 g of calcium oxide are formed. What is the
percentage yield of calcium oxide?
A.
B.
C.
D.
7%
25 %
50 %
75%
13. Chloroethene, C​2​H​3​Cl, reacts with oxygen according to the equation below:
2C​2​H​3​Cl + 5O​2​ ​→​ 4CO​2​ + 2H​2​O + 2HCl
How many moles of CO​2​ are produced when 3.0 mol of C​2​H​3​Cl and 3.0 mol of O​2​ are reacted?
A.
B.
C.
D.
2.4
3.0
4.0
6.0
14. When the equation C​4​H​10​ + O​2​ ​→ ​CO​2​ + H​2​O is balanced correctly, what is the coefficient for O​2​ ?
A.
B.
C.
D.
9
13
18
24
15. A student was asked to make some copper(II) sulfate-5-water (CuSO​4​.5H​2​O) by reacting
copper(II) oxide (CuO) with sulfuric acid.
a. Calculate the molar mass of copper(II) sulfate-5-water.
b. Calculate the amount (in mol) of copper(II) sulfate-5-water in a 10.0 g sample.
c. Calculate the mass of copper(II) oxide needed to make this 10.0 g sample.
16. The reaction below represents the reduction of iron ore to produce iron.
2Fe​2​O​3​ + 3C ​→​ 4Fe + 3CO​2
A mixture of 30 kg of Fe​2​O​3​ and 5.0 kg of C was heated until no further reaction occurred. Calculate
the maximum mass of iron that can be obtained from these masses of reactants.
17. An element X reacts with oxygen to form the oxide X​2​O​3​.
a. Write a balanced equation for the reaction.
b. If 2.199 g of the oxide was obtained from 1.239 g of X, calculate the relative atomic mass of
X and identify the element.
18. 100 cm​3​ of ethene, C​2​H​4​, is burned in 400 cm​3​ of oxygen, producing carbon dioxide and some
liquid water. Some oxygen remains unreacted.
a. Write the equation for the complete combustion of ethene.
b. Calculate the volume of carbon dioxide produced and the volume of oxygen remaining.
19. Follow
a. Write an equation for the formation of zinc iodide from zinc and iodine.
b. 100.0 g of zinc is allowed to react with 100.0 g of iodine producing zinc iodide. Calculate the
amount (in moles) of zinc and iodine, and hence determine which reactant is in excess.
c. Calculate the mass of zinc iodide that will be produced.
Topic 1 Quantitative Chemistry
1.3
Gaseous Volume Relationships & Mass and Gas Volume relationships
1. When the pressure is increased at constant temperature, the particles in a gas will
A. become smaller
B. become larger
C. move faster
D. closer together
2. For which set of conditions does a fixed mass of an ideal gas have the greatest volume?
Temperature
Pressure
A.
low
low
B.
low
high
C.
high
high
D.
high
low
3. Which expression represents the density of a gas sample of relative molar mass, M​r​, at temperature,
T, and pressure, P?
A.
B.
C.
D.
4. What will happen to the volume of a fixed mass of gas when its pressure and temperature (in
Kelvin) are both doubled?
A.
B.
C.
D.
It will not change.
It will increase.
It will decrease.
The change cannot be predicted.
5. A cylinder of gas is at a pressure of 40 kPa. The volume and temperature (in K) are both doubled.
What is the pressure of the gas after these changes?
A.
B.
C.
D.
10 kPa
20 kPa
40 kPa
80 kPa
6. A fixed mass of an ideal gas has a volume of 800 cm​3​ under certain conditions. The pressure (in
kPa) and temperature (in K) are both doubled. What is the volume of the gas after these changes with
other conditions remaining the same?
A.
B.
C.
D.
200 cm​3
800 cm​3
1600 cm​3
3200 cm​3
7. When a small quantity of a strongly smelling gas such as ammonia is released into the air, it can be
detected several metres away in a short time.
a. Use the kinetic molecular theory to explain why this happens.
b. State and explain how the time taken to detect the gas changes when the temperature is
increased.
8. Assuming ideal behaviour, calculate the volume occupied by 2.00g of carbon monoxide at 20
degree C under a pressure of 6250 N m-2
9. A 0.230 g sample of ​A​, when vaporized, had a volume of 0.0785 dm​3​ and a pressure of 102 kPa. at
95 C ° Determine the relative molecular mass of ​A​.
10. A 1.00 g sample of the hydrocarbon at a temperature of 273 K and a pressure of 1.01 10​5​ Pa (1.00
atm has a volume of 0.399 dm​3 ​) Calculate the molar mass of the hydrocarbon.
11. This question deals with gases and liquids.
a. The mass of a gas sample is measured under certain conditions. List the variables that must
be measured and show how these can be used to determine the molar mass of the gas.
b. As a volatile liquid in an isolated container evaporates, its temperature drops. Account for
this observation in terms of the behaviour of the molecules.
c. In hydrogen gas what happens to the average speed of the molecules if the temperature is
increased?
d. Explain, in terms of molecules, what happens to the pressure of a sample of hydrogen gas if
its volume is halved and the temperature kept constant.
Topic 1 Quantitative Chemistry
Solutions
1.4
1. Zn(s) + Cu​2+​(aq) ​→​ Zn​2+​ (aq) + Cu(s)
Powdered zinc reacts with Cu​2+​ ions according to the equation above. What will be the result of
adding 3.25 g of Zn to 100 cm​3​ of 0.25 mol dm -3​​ CuS0​4​ solution?
A.
B.
C.
D.
All the Cu +​​ ions react and some solid zinc remains.
All the Cu​2+​ ions react and no solid zinc remains.
All the solid zinc reacts and Cu​2+​ ions remain.
Neither solid zinc nor Cu​2+​ ions remain.
2.
CaCl​2​(aq) + 2AgNO​3​(aq) ​→ ​2AgCl(s) + Ca(NO​3​)​2​(aq)
3​
2.0 dm​ of 0.50 mol dm -3​​ CaCl​2​(aq) is mixed with 1.0 dm​3​of 2.0 mol dm -3​​ AgNO​3​(aq). What are the
concentrations of Ca​2+​(aq) and NO​3​-​(aq) after mixing?
3. Which sample contains the greatest number of ions?
A.
B.
C.
D.
25 cm​3​ of 0.40 mol dm -3​​ NaCl
50 cm​3​ of 0.20 mol dm -3​​ MgCl​2
100 cm​3​ of 0.10 mol dm -3​​ KNO​3
200 cm​3​ of 0.05 mol dm 3​​ CuSO​4​4.
4. 10.0 cm​3​ of 0.200 mol dm -3​​ H​3​PO​4​(aq) is converted into Na​2​HPO​4​(aq). What volume (in cm​3​) of
0.200 mol dm -3​​ NaOH(aq) is required?
A.
B.
C.
D.
10.0
13.3
20.0
30.0
5. 25.0 cm​3​ of 2.00 mol dm -3​​ HNO​3​(aq) reacts completely with 20.0 cm​3​ of Ba(OH)​2​(aq). What is
the concentration of barium hydroxide solution?
A.
B.
C.
D.
0.800 mol dm​-3
1.25 mol dm​--3
2.00 mol dm​-3
2.50 mol dm​-3
6. Which solution contains the greatest amount (in mol) of solute?
A.
B.
C.
D.
10.0 cm​3​ of 0.500 mol dm​-3​ NaCl
20.0 cm​3​ of 0.400 mol dm​-3​ NaCl
30.0 cm​3​ of 0.300 mol dm​-3​ NaCl
40.0 cm​3​ of 0.200 mol dm​-3​ NaCl
7. 16.20X10​-3​ dm​3​ of 0.1020 mol dm​-3​ aqueous AgNO​3​ is added to 14.80x10​-3​ dm​3​ of 0.1250 mol dm​-3
aqueous NaCl. Calculate the maximum mass (g) of AgCl which could be obtained from this reaction.
(Relative Atomic Masses are Ag = 107.87, Cl = 35.45.)
8. Vinegar is a solution of ethanoic acid. A 10.0 cm​3​ portion of a certain brand of vinegar needed 55.0
cm​3​ of 0.200 mol dm​-3​ sodium hydroxide solution to neutralise the ethanoic acid in it.
Ethanoic acid + Sodium hydroxide ​→​ Sodium ethanoate + Water
CH​3​CO​2​H(aq) + NaOH(aq) ​→​ CH​3​CO​2​Na(aq) + H​2​O(l)
Calculate the concentration of ethanoic acid in the vinegar in mol dm​-3​.
9. We placed 20.0 cm​3​ of a solution of barium hydroxide, Ba(OH)​2​, of unknown concentration in a
conical flask and titrated with a solution of hydrochloric acid, HC1, which has a concentration of
0.0600, mol dm​-3​. The volume of acid required is 25.0 cm​3​. Calculate the concentration of the barium
hydroxide solution.
Ba(OH)​2​ (aq) + 2HC1 (aq) ​→ ​BaCl​2​ (aq) + 2H​2​O (1)
10. A household cleaner contains aqueous ammonia. A 2.447 g sample of the cleaner is diluted with
water to 20.00 cm​3​. This solution requires 28.51 cm​3​ of 0.4040 mol dm​-3​ sulfuric acid to reach the
equivalence point.
a. Write a balanced chemical equation for the reaction of sulfuric acid with ammonia to form
ammonium sulfate.
b. Calculate the amount (moles) of sulfuric acid required for this reaction, and the amount
(moles), mass and percentage by mass of ammonia present in the household cleaner.
HL ONLY
11. A student wished to determine the percentage of calcium carbonate in a small sea shell found on a
local beach. The clean, dry shell that weighed 1.306g was placed in a small beaker and 10 cm​3​ of 5.00
mol dm​-3​ hydrochloric acid was added. After the shell had completely dissolved, the resulting solution
was carefully transferred to a volumetric flask and the volume was made up to 25.0 cm​3​ with distilled
water. A 10.0 cm​3​ sample of this solution required 11.2 cm of 1.00 mol dm​-3​ sodium hydroxide
solution for complete neutralisation.
a. Calculate the number of moles of NaOH present in 11.2​ ​cm​3​ of 1.00 mol dm​-3 ​NaOH solution.
b. How many moles of acid remained in the beaker after the reaction with the shell?
c. How many moles of acid reacted with the shell?
d. Write the equation for the reaction of calcium carbonate and hydrochloric acid.
e. What mass of calcium carbonate was present in the shell?
f.
What was the percentage of calcium carbonate in the shell?
g. What assumptions have you made about the composition of the shell in arriving at your
answer?