OCR A Level Chemistry B (Salters) H433/02 Scientific literacy in chemistry QUESTION PAPER Monday 20 June 2022 – Morning

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1 Portland cement is a powder that ‘sets’ to a strong solid when water is added. The cement is usually mixed with gravel so that it sets to make concrete. The typical ingredients of Portland cem... ent are shown in the table. Ingredients (solids) % by mass CaO 61 – 67 SiO2 19 – 23 Al 2O3 2.5 – 6 Fe2O3 0 – 6 SO3 1.5 – 4.5 (a) Give the systematic name for Fe2O3. .............................................................................................................................................. [1] (b) (i) A hazard warning for Portland cement states that it is alkaline. One of the ingredients in the table reacts with water to form an alkaline solution. Write an equation for the reaction of this ingredient with water including any ions that are formed. [2] (ii) When Portland cement sets, the calcium oxide absorbs carbon dioxide from the air. Suggest an equation for the reaction that occurs. [1] (c) One way of testing for the presence of calcium in the cement would be a flame test, though any iron present would interfere. (i) What is the flame colour of calcium? ...................................................................................................................................... [1] 3 © OCR 2022 Turn over (ii) The flame colour is caused by bright lines in the atomic emission spectrum of calcium. Explain how these lines are formed. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2] (iii) Calculate the frequency of a line of wavelength 6.16 × 10–7 m. frequency = ..................................................... Hz [2] (d) Fe2O3 and CaO are present in Portland cement. (i) In which ‘blocks’ of the periodic table are these elements found? Ca ...................................................................................................................................... Fe ................................................................................................................................. [1] (ii) The electron configuration of a calcium ion is 1s22s22p63s23p6. How does the electron configuration of the cation in Fe2O3 differ from this? ........................................................................................................................................... ...................................................................................................................................... [1] (iii) Explain why iron can form two stable cations. ........................................................................................................................................... ...................................................................................................................................... [1] (e) Fe2O3 is soluble in concentrated hydrochloric acid. Excess sodium hydroxide is added to this solution. Name the precipitate formed and describe its colour. name: ........................................................................................................................................ colour: .................................................................................................................................. [1] [Show More]

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