Industrial Question paper 2

Transcription

1 Level Subject Exam Board Industrial Question paper 2 IGCSE(9-1) Chemistry Edexcel IGCSE Module Single Award (Paper 2C) Topic Sub-Topic Industrial Booklet Question paper 2 Time Allowed: 21 minutes Score: /17 Percentage: /100 Grade Boundaries: >90% 80% 70% 60% 50% 40% 30% % 10%

2 1 The following verse is about water (H 2 O) and dilute sulfuric acid (H 2 SO 4 ). Johnny was a chemist s son But Johnny is no more What Johnny thought was H 2 O Was H 2 SO 4 (a) Johnny looked at a beaker containing sulfuric acid and thought that it was water. He then drank the liquid. Suggest why it is possible to mistake sulfuric acid for water. (b) Anhydrous copper(ii) sulfate changes from white to blue when added to dilute sulfuric acid. Suggest why. (c) Sulfuric acid is manufactured by the contact process. One stage of this process involves the reaction of sulfur dioxide with oxygen. 2 SO 2 + O 2 2 SO 3 State the conditions used in this stage of the process. (3) Pressure (in atmospheres) Temperature (in C) Catalyst

3 (d) 10.0 cm 3 of a concentrated solution of sulfuric acid was carefully diluted with water. More water was then added until the final volume of the solution was 1.00 dm 3 (1000 cm 3 ). In an experiment, a student found that 25.0 cm 3 of the diluted sulfuric acid reacted with cm 3 of sodium hydroxide solution. The concentration of the sodium hydroxide solution was mol/dm 3. The equation for the reaction is: 2NaOH + H 2 SO 4 Na 2 SO 4 + 2H 2 O (i) Calculate the amount, in moles, of sodium hydroxide in cm 3 of a solution of concentration mol/dm 3. (2) Amount of sodium hydroxide =... mol (ii) Using your answer to (d)(i), calculate the amount, in moles, of sulfuric acid in 25.0 cm 3 of the diluted acid. Amount of sulfuric acid in 25.0 cm 3 =... mol

4 (iii) Using your answer to (d)(ii), calculate the concentration, in mol/dm 3, of the diluted sulfuric acid. (2) Concentration of the diluted sulfuric acid =... mol/dm 3 (iv) Using your answer to (d)(iii), calculate the concentration, in mol/dm 3, of the original, concentrated sulfuric acid. Concentration of the original, concentrated acid =... mol/dm 3 (Total for Question 1 = 11 marks)

5 2 Sulfuric acid can be manufactured from sulfur in a four-stage process. stage 1 sulfur is burned in air to form sulfur dioxide S + O 2 SO 2 stage 2 the sulfur dioxide is reacted with more oxygen to form sulfur trioxide SO 2 + ½ O 2 SO 3 stage 3 the sulfur trioxide is absorbed in concentrated sulfuric acid to make oleum SO 3 + H 2 SO 4 H 2 S 2 O 7 stage 4 the oleum is carefully diluted with water to form sulfuric acid (a) Write a chemical equation for the formation of sulfuric acid from oleum.... (b) A mass of 80 tonnes of sulfur is reacted with oxygen in stage 1. Calculate the maximum mass, in tonnes, of sulfur trioxide that can be produced in stage 2. [1 tonne = g] (3)

6 (c) Calculate the minimum volume at rtp, in cubic decimetres (dm 3 ), of oxygen required to completely react with 64 tonnes of sulfur dioxide. [1 mol of oxygen at rtp has a volume of 24 dm 3 ] (2) volume of oxygen =...dm 3 (Total for Question 2 = 6 marks)