Zn
(s)
+ 2HCl
(aq)
ZnCl
2
(aq)
+ H
2
(g)
Avogadro Homework 1
1. Calculate the number of atoms present in
a) 4.6 g of sodium b) 1.25 moles of helium
2. Calculate the mass of a) zinc present in 3.01 x 10 22 zinc atoms. b) sulphur present in 1 x 10 20 sulphur atoms.
3. A sample of hydrogen sulphide (H
2
S) weighed 17 g.
2
1
1
How many hydrogen atoms are there in this sample?
4. Given 0.5 moles of glucose (C
6
H
12
O
6
), calculate
a) the mass of glucose present.
b) the number of oxygen atoms present.
5. Given 188 g of magnesium chloride (MgCl
2
), calculate the number of
a) moles of magnesium chloride present.
b) chloride ions present.
6. Calculate the mass of copper(II) chloride, CuCl
2
, required to make
200 cm 3 of a 0.25 mol l -1 solution of copper(II) chloride.
7. 5g of zinc is reacted with 400 ml of 1 mol l -1 hydrochloric acid.
1
1
1
1
1
3
The equation for the reaction is:-
Zn
(s)
+ 2HCl
(aq)
ZnCl
2
(aq)
+ H
2
(g)
a) Show by calculation which reactant is in excess?
b) Calculate the mass of any reactant left.
c) Calculate the mass of hydrogen gas formed in this reaction.
2
2
2
Total = 18

C
4
H
10
(g) + 6.5 O
2
(g) 4CO
2
(g) + 5H
2
O (l)
Zn
(s)
+ H
2
SO
4
(aq)
ZnSO
4
(aq)
+ H
2
(g)
CaCO
3
(s) + 2HCl (aq) CaCl
2
(aq) + CO
2
(g) + H
2
O (l)
Avogadro Homework 2
1. Calculate the volume composition of the gases present when 50 cm of butane is burned in 500 cm 3
C
4
H
10
(g)
+ 6.5 O
2
of oxygen.
(g)
4CO
2
(g)
+ 5H
2
O
(l)
3
2
2. Calculate the volume composition of the gases present when 45 cm 3 of propene is burned in 300 cm 3 of oxygen assuming that all measurements are made at a) room temperature. b) b) 200°C. 2
3. Calculate the volume of hydrogen gas formed when 3.25 g of zinc is reacted with an excess of dilute sulphuric acid. Take the molar volume of a gas, under the conditions of the experiment, to be 24.0 l mol –1 .
Zn
(s)
+ H
2
SO
4
(aq)
ZnSO
4
(aq)
+ H
2
(g) 2
4. Calculate the mass of calcium carbonate required to form 2.8 litres of carbon dioxide when the calcium carbonate is reacted with an excess of dilute hydrochloric acid. Take the molar volume of a gas, under the conditions of the experiment, to be 22.4 l mol
CaCO
3
(s)
+ 2HCl
(aq)
CaCl
2
(aq)
+ CO
2
–1 .
(g)
+ H
2
O
(l) 2
5. When copper(II) nitrate is heated strongly it decomposes to form copper(II) oxide, nitrogen dioxide and oxygen.
a) Write a balanced chemical equation for the decomposition of copper(II) nitrate 1
b) Calculate the volume of each gas present in the mixture formed when 18.4 g of copper(II) nitrate fully decomposes. Take the molar volume of a gas, under the conditions of the experiment, to be 23.8 litres.
2
6. A flask has a capacity of 600 cm 3 . It was filled with sulphur dioxide and the results used to calculate the molar volume of sulphur dioxide.
Results:- Mass of evacuated (empty) flask
Mass of flask filled with SO
2
=
= 412.86 g
414.46g
Use these results to calculate the molar volume of sulphur dioxide.
2
Total = 13

Avogadro Homework 3
1.
Mg + 2 HCl MgCl
2
+ H
2
0.1
moles of magnesium reacts with excess acid, calculate a.
the number of moles of acid required to completely react with the magnesium b.
the number of moles of magnesium chloride produced c.
the mass of magnesium chloride produced d.
the number of molecules of hydrogen produced e.
the volume of hydrogen produced (given the molar volume is 22 litresmol -1 ) f.
the number of chloride ions produced
2.
C + O
2
CO
2
1
1
1
1
1
1
2.4 g of carbon reacts with excess oxygen, calculate a.
the number of moles of carbon dioxide produced b.
the mass of carbon dioxide produced c.
the volume of carbon dioxide produced (given the molar volume
is 24 litres mol -1 ) d.
the number of molecules of carbon dioxide produced e.
the total number of atoms present in the carbon dioxide produced 1
1
1
3.
CH
4
+ 2 O
2
CO
2
+ 2 H
2
O
1
1 a.
b.
500 cm 3 of methane is burned in 2 litres of oxygen, calculate the volume of oxygen in excess the volume of carbon dioxide formed a.
4.
Calculate the number of: molecules in 3.2 g of methane b.
atoms in 7.1 g of chloride c.
formula units in 5.85 g of sodium chloride d.
ions in 5.85 g of sodium chloride c.
the number of molecules of carbon dioxide formed (given the molar volume is 24 litres mol -1 )
1
1
1
2
2
2
2
Total = 22