Homework 2 – Moles
1. 1 mol of hydrogen gas and 1 mol of chlorine gas were mixed and allowed to react.
After t seconds, 0.8mol of hydrogen remained.
The number of moles of hydrogen chloride formed at t seconds was
2. How many moles of magnesium will react with 20cm3 of 2 mol l-1 hydrochloric acid?
3. 63.5g of copper is added to 1 litre of 1 mol l-1 silver(I)nitrate solution.
Which of the following statements is always true for this reaction?
A. The resulting solution is colourless
B. All the copper dissolves
C. 63.5g of silver is formed
D. One mole of silver is formed
4. 5g of copper is added to silver nitrate solution. The equation for the reaction that
takes place is:
Cu(s) + 2AgNO3(aq) 2Ag(s) + Cu(NO3)2(aq)
After some time, the solid present is filtered from the solution, washed with water,
dried and weighed.
The final mass of the solid will be
A. less than 5g
D. more than 10g
5. In a reaction equal moles of acetone (formula mass 58amu) and phenol (formula mass
94 amu) are produced.
If 10 tonnes of acetone are obtained, calculate the mass of phenol produced. (2)
6. 1.6g of sodium hydroxide solid was added to 50cm3 of 1mol l-1 hydrochloric acid.
Which reactant is in excess? (2)
7. In a reaction 3050g of phenylethanol (mass of 1 mole = 122g) and 1480g of
propanoic acid (mass of 1 mole = 74g) react together.
Which reactant is in excess? (Given that an equation shows that 1 mole of
phenylethanol reacts with 1 mole of propanoic acid.) (2)
8. Airbags in cars are intended to prevent injuries in a car crash. They contain sodium
azide, NaN3 (s), which produces nitrogen if an impact is detected.
2NaN3(s) 3N2(g) + 2Na(s)
Calculate the mass of sodium azide required to produce 84g of nitrogen gas. (2)
9. The equation for an experiment is shown.
Mg(s) + H2SO4(aq) MgS04(aq) + H2(g)
In the experiment 0.50g of magnesium and 100 cm3 of 0.10 mol l-1 sulphuric acid was
For this experiment, calculate the mass of magnesium, in grams, left unreacted. (2)
10. If 1.64 kg of ethanol (relative formula mass = 46) is produced from 10 kg of ethene
(relative formula mass = 28), calculate the percentage yield of ethanol. (2)
11. Ethanol and ethanoic react to form the ester, ethyl ethanoate.
ethanol + ethanoic acid ethyl ethanoate + water
mass of one mole mass of one mole mass of one mole
= 46g = 60g = 88g
Use the above information to calculate the percentage yield of ethyl ethanoate, if
5g of ethanol produced 5.8g of ethyl ethanoate on reaction with excess
ethanoic acid. (2)
12. If there is a 65% yield, calculate the mass of ester produced, in grams, when 4.0g of
the alcohol reacts with a slight excess of the acid. (Given that an equation shows that
1 mole of ester is produced from 1 mole of alcohol.)
Mass of one mole of the alcohol = 88g
Mass of one mole of the ester = 130g (2)