C4 Chemical calculations Exam-style questions - Kerboodle

1 C4 Chemical calculations Exam-style questions 0 1 Limestone is mainly calcium carbonate. The formula of calcium carbonate is CaCO3. Complete Table 1 to show the number of atoms in limestone. [3 marks]. Table 1. Element Symbol Number of atoms Ca .. carbon .. oxygen .. 0 2 . 1 The mass number of an atom is the sum of two other sub-atomic particles. What are these two sub-atomic particles called? [2 marks].. 0 2 . 2 An atom with a mass number of 12 is used as the reference when calculating relative atomic masses. Which element is this an atom of? [1 mark]. A carbon B hydrogen C lead D oxygen 0 3 . 1 Ethanol is made in a reversible reaction form ethene and water. The equation is C2H4 + H2O C2H5OH. Which statement correctly describes the yield? [1 mark]. A mass of ethanol and water B mass of ethanol made C mass of ethene reacted D mass of reactants and products Oxford University Press 2016 This resource sheet may have been changed from the original.

2 1. C4 Chemical calculations Exam-style questions 0 3 . 2 A student calculated that the maximum theoretical mass of ethanol made in the reaction would be 90 g. In the practical the student actually made 60 g of ethanol. Calculate the percentage yield. Give your answer to 2 significant figures. Use the equation mass of product actually made percentage yield = 100 [3 marks]. maximum theoretical mass of product .. 0 3 . 3 Suggest one reason why the mass collected was less than expected. [1 mark]. A ethanol is a liquid B ethene is too reactive C reversible reaction D steam was used 0 4 Calcium oxide is produced by heating calcium carbonate. The equation for the reaction is: CaCO3 CaO + CO2. Use the equation to calculate the atom economy for the production of calcium oxide. Relative formula mass of desired product from equation Atom economy = 100. Sum of relative formula masses of all reactants from equations Relative formula masses: CaCO3 = 100, CaO = 56 [2 marks].

3 Oxford University Press 2016 This resource sheet may have been changed from the original. 2. C4 Chemical calculations Exam-style questions 0 5 . 1 Sodium hydroxide and sulfuric acid react together to produce sodium sulfate and water. Balance the equation for the reaction. [1 mark].. NaOH + H2SO4 Na2SO4 + .. H2O. 0 5 . 2 In the reaction, how does the mass of the products compare with the mass of the reactants? [1 mark].. 0 5 . 3 A student investigated the volume of sulfuric acid that reacted with 25 cm3 sodium hydroxide. Describe a titration method the student could use in this investigation. [6 marks].. 0 6 . 1 A student investigated the reaction of magnesium with oxygen. The student calculated that g of magnesium oxide would make g of magnesium oxide. The equation for the reaction is: 2Mg + O2 2 MgO. What mass of oxygen is required to produce g of magnesium oxide from g of magnesium? [1 mark].. Oxford University Press 2016 This resource sheet may have been changed from the original.

4 3. C4 Chemical calculations Exam-style questions 0 6 . 2 The student heated magnesium to produce magnesium oxide. Figure 1 shows the apparatus the student used. Figure 1. The student: weighed g of magnesium heated the crucible and magnesium when heating lifted up the lid slightly to let oxygen in but stopped magnesium oxide escaping heated until all the magnesium formed a white powder weighed the magnesium ribbon formed. Table 2 shows the student's results. Table 2. Trial 1 Trial 2 Trial 3 Trial 4. Mass of magnesium in g Mass of magnesium oxide in g Calculate the mean mass of magnesium oxide produced. Give your answer to 2 decimal places [3 marks].. Oxford University Press 2016 This resource sheet may have been changed from the original. 4. C4 Chemical calculations Exam-style questions 0 6 . 3 The student produced less magnesium oxide than expected. Suggest two reasons why. [2 marks].. 0 7 A student made two solutions solution A and solution B.

5 Solution A contained 5 g of copper sulfate in 50 cm3 of water. Solution B contains 10 g of copper sulfate in 100 cm3 of water. The student added solution B to solution A. The student concluded that the new solution is more concentrated because it has more copper sulfate dissolved in it. Is the student correct? Explain your answer. [3 marks].. Oxford University Press 2016 This resource sheet may have been changed from the original. 5.