Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Chemical Formulae, Equations and Calculations Part 2
144 practice questions
Topics covered
- Calculations involving gas volumes19 practice questions
- Calculating the volume of a certain number of moles19 practice questions
- Using the molar volume in calculations with chemical equations19 practice questions
- Concentrations of solutions19 practice questions
- Calculations with equations involving solutions19 practice questions
- The standard calculation19 practice questions
- Reversing the calculations20 practice questions
Practice questions
11–20 of 24 · Hard
Question 11
5 marks · Hard
Answer and see the solution →A student is given 3.90 g of ammonium chloride (NH₄Cl, Ar: N = 14, H = 1, Cl = 35.5) and asked to make 250 cm³ of a solution.
(a)[2 marks]Calculate the amount, in mol, of NH₄Cl in 3.90 g. (Give your answer to 2 decimal places.)
(b)[2 marks]Calculate the concentration, in mol/dm³, of the NH₄Cl solution prepared.
(c)[1 mark]State the concentration in g/dm³ for this solution.
Question 12
2 marks · Hard
Answer and see the solution →A solution contains 0.036 mol of sodium sulfate (Na₂SO₄) in 0.300 dm³ of solution. Calculate the concentration of sodium sulfate in mol/dm³. Show your answer to 2 decimal places.
Question 13
2 marks · Hard
Answer and see the solution →Sodium carbonate reacts with hydrochloric acid according to the following equation:
If 0.06 mol of hydrochloric acid, HCl, are used in the reaction, calculate the number of moles of sodium carbonate, Na2CO3, that will completely react.
Question 14
5 marks · Hard
Answer and see the solution →Ethanoic acid reacts with sodium hydroxide as follows:
A student mixes 30 cm³ of 0.40 mol/dm³ ethanoic acid with excess sodium hydroxide.
(a)[2 marks]Calculate the number of moles of ethanoic acid used.
(b)[3 marks]Calculate the mass of sodium acetate (CH₃COONa) produced. (Relative formula mass: CH₃COONa = 82)
Question 15
2 marks · Hard
Answer and see the solution →Calculate the number of moles of sulfuric acid, H₂SO₄, in 75 cm³ of solution with concentration 0.20 mol/dm³.
Question 16
2 marks · Hard
Answer and see the solution →A student is titrating calcium hydroxide solution with hydrochloric acid. The balanced chemical equation for the reaction is:
Use the balanced equation to state the mole ratio of calcium hydroxide to hydrochloric acid and explain how this ratio is used in a titration calculation.
Question 17
5 marks · Hard
Answer and see the solution →A chemistry student carries out a titration to determine the concentration of a potassium hydroxide () solution. She finds that 25.0 cm³ of solution of unknown concentration reacts exactly with 20.0 cm³ of 0.200 mol/dm³ sulfuric acid (). The balanced equation for the reaction is:
Use the three-step titration calculation method to find the concentration of the solution.
(a)[1 mark]Calculate the number of moles of reacted.
(b)[1 mark]Use the balanced equation to work out the number of moles of that reacted.
(c)[2 marks]Calculate the concentration of in mol/dm³.
(d)[1 mark]State the three-step titration calculation method used in this problem.
Question 18
2 marks · Hard
Answer and see the solution →In a titration experiment, a student uses 15.0 cm³ of 0.150 mol/dm³ hydrochloric acid to neutralise a sodium carbonate solution. Calculate the number of moles of hydrochloric acid that were used. Give your answer to three significant figures.
Question 19
2 marks · Hard
Answer and see the solution →A student wants to completely neutralise 10.0 cm³ of 0.200 mol/dm³ nitric acid with sodium carbonate solution. The balanced equation for the reaction is:
Calculate the minimum volume, in cm³, of 0.100 mol/dm³ sodium carbonate solution required to react fully with the nitric acid.
Question 20
5 marks · Hard
Answer and see the solution →Calcium hydroxide solution reacts with hydrochloric acid according to the following balanced equation:
In a titration, 25.0 cm³ of hydrochloric acid solution of concentration 0.120 mol/dm³ is reacted completely with calcium hydroxide solution.
(a)[1 mark]Calculate the number of moles of HCl present in 25.0 cm³ of solution.
(b)[1 mark]Determine the number of moles of Ca(OH)₂ required to react with this amount of HCl.
(c)[2 marks]Given that the concentration of Ca(OH)₂ is 0.0800 mol/dm³, calculate the volume (in cm³) of Ca(OH)₂ solution that supplies this amount of Ca(OH)₂.
(d)[1 mark]Explain briefly why it is important to use the balanced equation when carrying out these calculations.