8 Worksheet
Group 2: Magnesium and calcium
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Magnesium metal is used in the production of titanium. Over 80 000 tonnes of titanium metal
are produced per year. Most of this is used to make aircraft; in particular to make parts of the
engines of modern jets. Titanium is produced in two stages. Firstly, the titanium ores are used
to make titanium tetrachloride, TiCl4, which is a liquid. Secondly, magnesium metal is added
to the titanium tetrachloride and these two chemicals react to make titanium and magnesium
chloride. The magnesium chloride is electrolysed.
a Do you expect the structure of titanium tetrachloride to be giant ionic or simple covalent?
Give a reason for your answer.
b Write an equation for the reaction of magnesium with titanium tetrachloride.
c What are the oxidation states of magnesium, titanium and chlorine before and after this
reaction?
d Which element is oxidised in this reaction and which element is reduced?
e When the magnesium chloride is electrolysed, magnesium and chlorine are formed.
Write a half-equation for the formation of magnesium from magnesium ions.
f Is magnesium oxidised or reduced in this process?
g What large-scale use could be made of the chlorine within the titanium production plant?
Much limestone (CaCO3) is quarried in the UK. The limestone can then be heated in lime kilns
to make lime (CaO). If water is added to lime they react to make slaked lime (Ca(OH)2), which
is used extensively in agriculture. Slaked lime is not very soluble in water, but its solution,
known as lime water, is useful. If carbon dioxide gas is bubbled into lime water, the lime water
goes cloudy at first; but if the carbon dioxide gas keeps on being added, the lime water will
eventually go clear again.
a Write a balanced chemical equation for the reaction in which lime is produced from
limestone.
b Write a balanced chemical equation for the reaction in which slaked lime is produced
from lime.
c Explain why ‘slaked lime is used extensively in agriculture’.
d What chemical property of slaked lime is important here?
e Write a balanced chemical equation for the first reaction between lime water and carbon
dioxide. Include state symbols.
Total
COAS Chemistry 1 Teacher Resources
22
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Original material © Cambridge University Press 2005, 2008
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