Unit F335 - Chemistry by design - Specimen.PDF, 434KB - OCR

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4 CH4(g) + H2O(g) CO(g) + 3H2(g) equation 1.2 (d) The mixture of gases from the reaction in equation 1.2 is mixed with more steam and passed over a hot iron catalyst. The carbon monoxide is converted to carbon dioxide. (i) Write an equation for the reaction of carbon monoxide with steam. (ii) Suggest two reasons why the carbon monoxide is not released into the atmosphere. ............................................................................................................................................. ............................................................................................................................................. ........................................................................................................................................ [2] (e) (i) Predict the sign of ∆Ssys for the forward reaction in equation 1.2. Explain your reasoning. ............................................................................................................................................. ............................................................................................................................................. ........................................................................................................................................ [1] (ii) Use the entropy data given in the table below to calculate the value of ∆Ssys (with the correct sign) for the forward reaction in equation 1.2. compound S/J K –1 mol –1 CH4(g) +186 H2O(g) +189 CO(g) +198 H2(g) +131 (iii) At 500 K the value of ∆Stot for the forward reaction is –1784. Calculate the value of ∆Stot at 1000 K. Assume that ∆Ssys does not change with temperature. [1] ∆Ssys............................................J K –1 mol –1 [3] ∆Stot =............................................J K –1 mol –1 [2] [Total: 24]
2 The pigment chrome yellow consists of lead chromate(VI), PbCrO4. It is made <strong>by</strong> precipitation when solutions of lead nitrate and sodium chromate(VI) are mixed. (a) Explain why (VI) is used to describe the CrO4 2– ion. 5 ................................................................................................................................................. [1] (b) Write an ionic equation for the precipitation of lead chromate(VI), showing state symbols. (c) Pigments can be identified <strong>by</strong> their visible reflectance spectra. The spectra of three pigments are shown below, lettered A, B and C. reflectance (%) 400 500 600 700 wavelength/nm reflectance (%) Suggest, with a reason, which is the reflectance spectrum of chrome yellow. ............................................................................................................................................................ ............................................................................................................................................................ ....................................................................................................................................................... [2] (d) The diagram below helps to explain the yellow colour of the chromate ion. (i) Which electron sub-shell is shown in the diagram? A reflectance (%) B 400 500 600 700 wavelength/nm ........................................................................................................................................ [1] (ii) What causes the splitting of the orbitals within the sub-shell? 400 500 600 700 wavelength/nm ........................................................................................................................................ [1] C [2] [Turn over
Page 1 and 2: Advanced GCE CHEMISTRY B (SALTERS)
Page 3: 3 (ii) At the temperature of the re
Page 7 and 8: 7 (f) Lead chromate(VI) is insolubl
Page 9 and 10: (c) Sunscreens absorb ultraviolet r
Page 11 and 12: 11 (v) The ionic liquid contains th
Page 13 and 14: 13 (ii) Suggest why both of these m
Page 15 and 16: (f) A mixture of GHB and its sodium
Page 17 and 18: 17 (c) When light shines on the rod
Page 19 and 20: Copyright Acknowledgements: Sources
Page 21 and 22: OXFORD CAMBRIDGE AND RSA EXAMINATIO
Page 23 and 24: Question Number 3 Answer Max Mark 2
Page 25 and 26: Question Number 5 Answer Max Mark (
Page 27 and 28: 7 Assessment Objectives Grid (inclu

Unit F335 - Chemistry by design - Specimen.PDF, 434KB - OCR

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