Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Reversing the calculations
20 practice questions
Practice questions
1–10 of 20
Question 1
1 mark · Easy
Answer and see the solution →What is the formula used to calculate the volume (in dm³) of a solution, given the number of moles and concentration in mol/dm³?
Question 2
3 marks · Easy
Answer and see the solution →Potassium hydroxide reacts with nitric acid according to the equation:
25.0 cm³ of 0.200 mol/dm³ potassium hydroxide solution is mixed with 25.0 cm³ of 0.200 mol/dm³ nitric acid.
(a)[1 mark]Calculate the number of moles of potassium hydroxide in the mixture.
(b)[1 mark]Calculate the number of moles of nitric acid in the mixture.
(c)[1 mark]State the simplest whole-number ratio of reactant volumes needed for complete neutralisation according to the equation.
Question 3
2 marks · Easy
Answer and see the solution →Calculate the volume in cm³ of 0.150 mol/dm³ sulfuric acid solution that contains 0.0300 mol of sulfuric acid.
Question 4
2 marks · Easy
Answer and see the solution →Explain why, when rearranging the concentration equation to solve for volume, the number of moles must be divided by concentration, and not the other way around.
Question 5
3 marks · Easy
Answer and see the solution →The following table shows the reaction between sodium sulfate and barium chloride:
Reactant Volume (cm³) Concentration (mol/dm³) Sodium sulfate 50.0 0.100 Barium chloride excess — Use the data given to answer the following:
(a)[1 mark]Calculate the number of moles of sodium sulfate used.
(b)[1 mark]Use the balanced equation to state how many moles of barium sulfate will be formed.
(c)[1 mark]State the minimum volume of sodium sulfate solution (in cm³) needed to ensure 0.0100 mol of barium sulfate forms, using the same concentration.
Question 6
1 mark · Easy
Answer and see the solution →State the information you must know to calculate the volume of a solution required to react with a known amount of another reactant.
Question 7
3 marks · Easy
Answer and see the solution →20.0 cm³ of a solution contains 0.00400 mol of a substance.
(a)[1 mark]Calculate the volume of the solution in dm³.
(b)[1 mark]Calculate the concentration of the solution in mol/dm³.
(c)[1 mark]State the formula used for this calculation.
Question 8
2 marks · Easy
Answer and see the solution →Nitric acid reacts with sodium carbonate according to the following equation:
Calculate the minimum volume, in cm³, of 0.250 mol/dm³ nitric acid solution needed to completely react with 25.0 cm³ of 0.100 mol/dm³ sodium carbonate solution.
Question 9
2 marks · Normal
Answer and see the solution →Sodium carbonate solution reacts with hydrochloric acid:
Calculate the volume (in cm³) of 0.200 mol/dm³ sodium carbonate solution required to completely react with 30.0 cm³ of 0.400 mol/dm³ hydrochloric acid.
Question 10
4 marks · Normal
Answer and see the solution →A laboratory technician needs to prepare a solution containing 0.00250 mol of silver nitrate (AgNO₃) and wants the final concentration to be 0.0500 mol/dm³.
(a)[1 mark]Write the equation used to calculate the required volume (in dm³) of solution.
(b)[2 marks]Calculate the volume of solution (in dm³) required to obtain the stated concentration.
(c)[1 mark]Convert your answer to part (b) into cm³.