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

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 cement 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]

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 (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]

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 (f) (i) A student has a solution containing Fe3+(aq) and reads that it will react with iodide ions

to form iodine. The iodine can then be titrated with sodium thiosulfate.

 Describe a method to measure the volume of sodium thiosulfate solution required to

react with the iodine from 25 cm3 of Fe3+(aq).

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...................................................................................................................................... [5]

 (ii) The student finds that 25.0 cm3 of Fe3+(aq) requires 3.2 cm3 of 0.510 mol dm–3 sodium

thiosulfate.

 Calculate the concentration of the Fe3+(aq).

 2Fe3+ + 2I– 2Fe2+ + I2

 2S2O3

2– + I2 S4O6

2– + 2I–

 Give your answer to an appropriate number of significant figures.

[Fe3+] = ........................................... mol dm–3 [3]

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 (iii) The student decides to repeat the experiment using 0.0510 mol dm–3 sodium thiosulfate.

 Suggest why the student does this.

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...........................................................................................................................................

 ...................................................................................................................................... [2]

 (g) Iron is formed in stars by fusion reactions.

 Complete the nuclear equation for one such reaction.


48

24........ + .....

.....He

.....

.....Fe [2]

 (h) The table shows the stable isotopes of iron and their abundances.

Mass number Abundance /

%

54 5.85

56 91.75

57 2.12

58 0.28

 (i) What is meant by the term mass number?

 ...........................................................................................................................................

 ...................................................................................................................................... [1]

 (ii) Explain, without doing a calculation, how this data shows that the relative atomic mass

of iron is below 56.

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Version LATEST 2022
Category OCR
Release date 2022-07-13
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Authors Qwivy.com
Pages 20
Language English
Tags OCR A Level Chemistry B (Salters) H433/02 Scientific literacy in chemistry Question Paper
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