This document contains exam done on May 2022 OCR AS Level Chemistry B (Salters) H033/02 Chemistry in depth Question Paper. Download PDF to score an A+
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Answer all the questions.
1 The element magnesium is an important Group 2 metal. Its presence in distant stars has been
shown using atomic emission spectra.
(a) (i) The atomic emission spectrum of an element shows a series of coloured lines on a
black background.
Describe how the appearance of the absorption spectrum of the element is similar to
and different from its emission spectrum.
Similar ...............................................................................................................................
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Different .............................................................................................................................
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[2]
(ii) What evidence for the structure of atoms is provided by atomic spectra?
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(b) Ionisation enthalpies have also been used to develop theories about atomic structure.
(i) Write an equation for the reaction that represents the first ionisation enthalpy of
magnesium.
Include state symbols.
[2]
(ii) The first ionisation enthalpies of the elements of Period 3 show a general increase
across the period.
Explain this increase.
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(c) The mass spectrum of magnesium shows that it has three stable isotopes as shown below.
Isotope Abundance / %
24Mg 78.60
25Mg 10.11
26Mg 11.29
Calculate a value for the relative atomic mass of magnesium based on these data.
Give your answer to two decimal places.
relative atomic mass = .......................................................... [2]
(d) Magnesium-24 is formed in some stars by nuclear fusion of two identical carbon nuclei.
Complete the nuclear equation for the formation of this isotope.
2
24
12 Mg [1]
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(e) A student is asked to prepare a sample of hydrated magnesium chloride crystals (containing
water of crystallisation) starting from solid magnesium oxide.
The student adds magnesium oxide to hot hydrochloric acid until the oxide is in excess.
The student then evaporates the mixture until just a solid is left.
Explain why this procedure would not produce hydrated magnesium chloride crystals and
give a correct method.
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(f) Calcium and barium are two other Group 2 elements.
A student places a small piece of calcium into 100 cm3 of cold water in a beaker. A steady
fizzing occurs, the calcium disappears and a white, cloudy mixture of pH 11 is left. The
temperature increases by 26 °C.
The student then repeats the experiment with an equal amount of barium.
Describe two differences that the student would observe when comparing the reaction of
barium with that of calcium.
1 ................................................................................................................................................
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2 ................................................................................................................................................
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[2]
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(g) Another student is provided with samples of magnesium carbonate and strontium carbonate
and asked to identify which is which. The student heats equal amounts of each carbonate in
separate test tubes using the same Bunsen flame. The student measures the time taken for
the gas evolved to turn limewater cloudy.
The student says that the time taken will be shorter when strontium carbonate is heated
because strontium is more reactive than magnesium.
Comment on the student’s statement, giving the correct chemistry where necessary.
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(h) Complete the electronic configuration for the magnesium ion, Mg2+.
1s2 ...................................................................................................................................... [1]
OCR chemistry a level
Version | LATEST 2022 |
Latest update | 2022-07-16 |
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Authors | Qwivy.com |
Pages | 20 |
Language | English |
Tags | OCR AS LEVEL CHEMISTRY B Salters H033/02 Chemistry in Depth Salters B Chemistry Chemistry B OCR Chemistry B Chemistry B Salters AS level Chemistry |
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