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
141–144 of 144
Question 141
6 marks · Normal
Answer and see the solution →A chemistry class investigates the reaction between solid calcium carbonate and dilute sulfuric acid. The reaction is:
(a)[2 marks]Explain why, after a short time, the reaction between calcium carbonate and dilute sulfuric acid slows down, even though there is still acid present.
(b)[2 marks]A student wants to calculate the concentration (in mol/dm³) of sulfuric acid if 5.0 g of CaCO3 is completely reacted using 250 cm³ of acid. (Ar: Ca = 40, C = 12, O = 16)
(c)[2 marks]The same student collects the carbon dioxide produced. Explain how they can use the volume of CO₂ collected at rtp to check if the reaction went to completion.
Question 142
7 marks · Hard
Answer and see the solution →Ammonium chloride reacts with sodium hydroxide according to the following equation:
A student adds 50.0 cm³ of 1.20 mol/dm³ sodium hydroxide solution to an excess of ammonium chloride solution in a flask at room temperature and pressure (rtp).
(a)[1 mark]Calculate the number of moles of sodium hydroxide added.
(b)[1 mark]Determine the maximum number of moles of ammonia gas (NH₃) that could be produced from this amount of sodium hydroxide.
(c)[2 marks]Calculate the volume (in cm³) of ammonia gas produced at rtp.
(d)[3 marks]The student wants to repeat the experiment but only collect 480 cm³ of ammonia gas at rtp. Calculate the minimum volume (in cm³) of 1.20 mol/dm³ sodium hydroxide solution required to produce this amount of ammonia gas.
Question 143
7 marks · Hard
Answer and see the solution →Calcium reacts with hydrochloric acid to produce hydrogen gas according to the following equation:
A student wants to produce exactly 600 cm³ of hydrogen gas at room temperature and pressure (rtp). The concentration of hydrochloric acid available is 0.500 mol/dm³.
(a)[1 mark]Calculate the number of moles of hydrogen gas required to produce 600 cm³ of gas at rtp.
(b)[1 mark]Calculate the number of moles of hydrochloric acid (HCl) needed to react to produce this amount of hydrogen gas.
(c)[3 marks]Calculate the volume (in cm³) of 0.500 mol/dm³ hydrochloric acid solution required to produce 600 cm³ of hydrogen gas.
(d)[2 marks]If the same volume of hydrogen gas (600 cm³) is to be produced, what is the corresponding volume (in cm³) at rtp if measured in dm³?
Question 144
7 marks · Hard
Answer and see the solution →A student reacts sodium carbonate solution with excess hydrochloric acid at room temperature and pressure (rtp). The equation for the reaction is:
The student wants to produce exactly 2.40 dm³ of carbon dioxide gas measured at rtp.
(a)[1 mark]Calculate the number of moles of carbon dioxide that occupy 2.40 dm³ at rtp.
(b)[1 mark]Using the chemical equation, determine the number of moles of sodium carbonate required to produce this volume of carbon dioxide.
(c)[3 marks]The student has 0.500 mol/dm³ sodium carbonate solution. Calculate the volume of this solution, in cm³, needed to provide the amount of sodium carbonate calculated in part b.
(d)[1 mark]State the conversion factor you would use to convert a volume in dm³ to cm³.
(e)[1 mark]Explain why the molar volume of a gas at rtp is used in this calculation.