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Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5 The production of Ammonia.

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Presentation on theme: "Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5 The production of Ammonia."— Presentation transcript:

1 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5 The production of Ammonia

2 Using Exam pro items to support successful outcomes Version 2.0 Copyright © AQA and its licensors. All rights reserved. Learners will be able to test their progress against learning outcomes using questions from past AQA GCSE examinations C3 3.5

3 Foundation Tier QSP 3F 04 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5

4 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5

5 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5

6 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5

7 Mark scheme- Foundation Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5 Q 1AnswerExtra InformationMark (a) (i) (gas X) nitrogen/N 2 (gas Y) hydrogen/H (a) (ii) cooled1 (b) any two from: save materials/resources save energy/fuels reduce costs reduce waste 2 (c) (i) low high 1111 (c) (ii) 40(%)1

8 Mark scheme- Foundation Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5 Q 2AnswerExtra Information Mark (c) (iii) any two from: using these conditions the yield is still high higher pressures would increase yield but energy costs would be higher or higher pressures would increase yield but would make the plant expensive to build the temperature of 450 °C would not need a lot of energy or at 450 °C the reaction would be faster than at lower temperatures 2 Total10

9 Higher Tier QCJ 99 H2 08 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5

10 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5

11 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5

12 Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5

13 Mark scheme- Higher Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5 Q 1AnswerExtra InformationMark (a) (i) both scales plots for 350°C plots for 500°C lines of best fit (must be sensible) (use at least half the paper ) (to accuracy of +/- 1/2 square) (sensible smooth curves) (ignore below 50 atm.) (must not join the dots and each curve must be a single line) 4 (a) (ii) read accurately from their graph(must be 350 °C and pressure read to +/– half square from their graph) for one mark 1 (a) (iii) smooth curve drawn between 350 o C and 500 °C - must be of similar shape to the other curves - a dashed line would be accepted here but would not be accepted for part (i) 1 (b)(i) reversible reaction (owtte) / equilibrium / equilibria / reaction goes in both directions etc. 1

14 Mark scheme- Higher Version 2.0 Copyright © AQA and its licensors. All rights reserved. C3 3.5 Q 2AnswerExtra InformationMark b) (ii) effect of temperature (max. 2 marks) best yield at low temperature / poor yield at high temperature reaction too slow at low temperature / fast at high temperature effect of pressure (max. 2 marks) high yield at high pressure (owtte) / low yield at low pressure ideas to do with cost / safety factor of using higher pressures evaluation (max. 2 marks) formation of ammonia favoured at low temperature because reaction is exothermic formation of ammonia favoured at high pressure because more reactant molecules than product molecules actual temperature and / or pressure used are a compromise between good yield and reasonable rate ammonia removed / unreacted nitrogen and hydrogen recycled so rate more important than yield catalyst used (not a wrongly named catalyst) for 1 mark each maximum of 2 marks from each section up to a maximum total of 5 (c) (i) NH 4 NO 3 = 14 + (4 × 1) (3 × 16) = 80(ignore units) 1 (c) (ii) look for (28/80) for first mark but 35% special case of (14/80 × 100 = 17.5%) gains one mark gains 2 marks ecf (error carried forward from part (i) (% sign not needed) 2 Total15

15 C3 3.5


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