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
111–120 of 144
Question 111
3 marks · Normal
Answer and see the solution →A student carries out a titration to find the concentration of a sulfuric acid solution. She adds exactly 25.0 cm³ of sodium hydroxide solution of known concentration, 0.150 mol/dm³, to a conical flask. She slowly adds sulfuric acid from a burette, using methyl orange as an indicator, until the indicator just changes colour. She records that she has used 30.0 cm³ of sulfuric acid to reach the endpoint. The balanced chemical equation for the reaction is:
Explain carefully how you would use these results to calculate the concentration of the sulfuric acid.
Question 112
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 113
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 114
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 115
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 116
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 117
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 118
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 119
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 120
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.