Quantitive Chemistry Question paper

Transcription

1 Quantitive Chemistry Question paper Level Subject Exam Board Topic Sub-Topic Booklet GCSE Chemistry CCEA Quantitative Chemistry Quantitive Chemistry Question paper Time Allowed: 93 minutes Score: /77 Percentage: /100

2 FOUNDATION TIER

3 1 Sea water contains a range of dissolved salts. (a) Complete the table below for some of the salts present in seawater. Name of Salt Formula Relative Formula Mass MgCl 2 Sodium sulfate Na 2 SO 4 [3] (ii) The most abundant salt present in seawater is sodium chloride, NaCl. Calculate the number of moles of sodium chloride in kg. (Relative atomic masses: Na = 23; Cl = 35.5) Moles of NaCl = [3] (iii) Sodium chloride may be obtained by reacting sodium hydroxide with hydrochloric acid. Write a balanced symbol equation for this reaction. [2]

4 (b) Magnesium chloride has healing effects on a wide range of diseases. The hydrated form of magnesium chloride contains water of crystallisation and has the formula MgCl 2.6H 2 O. What is meant by the term water of crystallisation? [1] (ii) Calculate the relative formula mass of hydrated magnesium chloride, MgCl 2.6H 2 O. (Relative atomic masses: H = 1; O = 16; Mg = 24; Cl = 35.5) Relative formula mass = [1] (iii) Use the value calculated in (b)(ii) to find the percentage of water of crystallisation in hydrated magnesium chloride. Percentage of water = %[2]

5 (iv) Describe how water of crystallisation may be removed from hydrated salts and how you would ensure that all of the water of crystallisation has been removed. [2]

6 2 (a) Whitening toothpastes contain hydrogen peroxide which bleaches teeth. During the bleaching process the hydrogen peroxide decomposes to produce water and oxygen. Balance the equation for this reaction below. H 2 O 2 H 2 O 1 O 2 [1] (ii) The molecular formula of hydrogen peroxide is H 2 O 2. What is its empirical formula? [1] (b) The table below shows the chemical formula and relative formula mass of other chemicals which can be present in whitening toothpastes. Substance Sodium fluoride Sodium hydrogen carbonate Hydrated silica Sodium lauryl sulfate Chemical Formula SiO 2.2H 2 O CH 3 (CH 2 ) 11 SO 4 Na Relative Formula Mass 84 Complete the table. [5]

7 (ii) Hydrated silica contains water of crystallisation. What is meant by the term water of crystallisation? [2] (iii) Calculate the percentage of water of crystallisation present in hydrated silica. (Relative atomic masses: H = 1; O = 16; Si = 28). Percentage of water = % [2] (iv) How many different types of atoms are present in sodium lauryl sulfate? [1]

8 (c) Hydrated aluminium oxide may also be present in whitening toothpastes. In an experiment, hydrated aluminium oxide was heated to remove all of the water of crystallisation. When 3.12 g of hydrated aluminium oxide were heated, 2.04 g of anhydrous aluminium oxide (Al 2 O 3 ) remained. (Relative atomic masses: H = 1; O = 16; Al = 27) Calculate the mass of water in 3.12 g of hydrated aluminium oxide. g [1] (ii) Calculate the number of moles of water in 3.12 g of hydrated aluminium oxide. mol [2] (iii) Calculate the number of moles of anhydrous aluminium oxide. mol [2]

9 3 (a) The photograph below shows Seizure, an artwork by Roger Hiorns which won the Turner Prize in An apartment was made watertight and filled with hot saturated copper(ii) sulfate solution. The solution was allowed to cool and crystallise leaving the walls, floor and ceiling covered in hydrated copper(ii) sulfate crystals. Examiner Only Marks Remark An image of an apartment with the walls, floor and ceiling covered in hydrated copper(ii) sulphate crystals has been removed due to copyright restrictions What is meant by the term hydrated? [1] (ii) What colour is hydrated copper(ii) sulfate? [1] (iii) What is meant by a saturated solution? [1]

10 (b) The table below shows values for the solubility of copper(ii) sulfate. Examiner Only Marks Remark Temperature ( C) Solubility (g/100 g water) Explain what is meant by the term solubility. [4] (ii) Use the data in the table to plot a solubility curve for copper(ii) sulfate on the axes below. [3]

11 (c) Use the graph in (b)(ii) to answer the following questions. What is the solubility of copper(ii) sulfate at 50 C? Examiner Only Marks Remark Solubility of copper(ii) sulfate 5 g/100 g water [1] (ii) Calculate the mass of copper(ii) sulfate which will saturate 10 g of water at 30 C. Mass of copper(ii) sulfate 5 g [2] (iii) At what temperature will 60 g of copper(ii) sulfate saturate 100 g of water? Temperature 5 C [1] (iv) A sample of 10 g of copper(ii) sulfate is added to a saturated solution of copper(ii) sulfate in 100 g of water at 60 C. What mass from the 10 g sample of copper(ii) sulfate would dissolve? [1] Total Question 3

12 HIGHER TIER

13 4 Magnesium compounds have many important and wide-ranging uses. Magnesium nitrate is used as a fertiliser and is also present in many cosmetics including hair conditioner. (a) On heating, magnesium nitrate breaks down according to the equation below: 2Mg(NO 3 ) 2 (s) 2MgO(s) 1 4NO 2 (g) 1 O 2 (g) What term is used to describe a reaction in which a substance breaks down when heated? [2] (ii) Calculate the mass of nitrogen dioxide, NO 2, produced when 4.44 g of magnesium nitrate are heated. (Relative atomic masses: N = 14; O = 16; Mg = 24) Mass of nitrogen dioxide g[5]

14 (b) Magnesium chloride has healing effects on a wide range of diseases. The hydrated form of the salt has the formula MgCl 2.nH 2 O. (Relative atomic masses: H = 1; O = 16; Mg = 24; Cl = 35.5) The following results were obtained in an experiment to determine the value of n in the formula. Mass of empty crucible = g Mass of crucible and hydrated magnesium chloride = g Mass of crucible and anhydrous magnesium chloride = g Calculate the mass of water of crystallisation lost. Mass of water g[1] (ii) Calculate the number of moles of water of crystallisation lost. Moles of water [1] (iii) Calculate the mass of the anhydrous magnesium chloride. Mass of anhydrous magnesium chloride = g [1] (iv) Calculate the number of moles of anhydrous magnesium chloride. Moles of anhydrous magnesium chloride = [ 1]

15 (v) Using your answer to parts (ii) and (iv), calculate the value of n in MgCl 2.nH 2 O. n = [ 1] (c) Magnesium chloride is produced when magnesium hydroxide reacts with dilute hydrochloric acid. The balanced symbol equation for this reaction is shown below: Mg(OH) 2 1 2HCl MgCl 2 1 2H 2 O A pharmaceutical company needs to produce tonnes of magnesium chloride for use in the manufacture of health supplements. Calculate the mass of hydrochloric acid, in kg, required to produce tonnes of magnesium chloride. (1 tonne = 1000 kg) Mass of hydrochloric acid = kg [5]

16 5 (a) Limestone, CaCO 3, is used as a building material and in the production of lime. Examiner Only Marks Remark When heated strongly calcium carbonate breaks down to produce lime and carbon dioxide gas as shown in the following equation. CaCO 3 CaO 1 CO 2 What name is given to this type of reaction? [2] (ii) Calculate the maximum mass of calcium oxide produced when 600 g of calcium carbonate are heated strongly. (Relative atomic masses: C 5 12; O 5 16; Ca 5 40) g [5]

17 (b) The metal titanium reacts with oxygen to form an oxide of titanium. In an experiment to determine the formula of the oxide, a sample of titanium metal was heated in a crucible with a tightly fitting lid. During heating the lid was lifted from time to time. Examiner Only Marks Remark The following results were obtained: Mass of crucible Mass of crucible 1 titanium metal Mass of crucible 1 oxide g g g Suggest why it was necessary to lift the crucible lid during heating. [1]

18 (ii) Use the results of the experiment to determine the empirical formula for the oxide of titanium. Examiner Only Marks Remark (Relative atomic masses: O 5 16; Ti 5 48) Empirical formula [6] Total Question 3