Magnesium and calcium are in group 2 of the periodic table - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2016 - Paper 1
Question 2
Magnesium and calcium are in group 2 of the periodic table. They are less reactive than the metals in group 1.
(a) Calcium reacts with water to form calcium hydroxi... show full transcript
Worked Solution & Example Answer:Magnesium and calcium are in group 2 of the periodic table - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2016 - Paper 1
Step 1
Describe what would be seen when a piece of calcium is dropped into a container of water.
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Answer
When a piece of calcium is dropped into a container of water, it will react vigorously, producing bubbles of hydrogen gas. The calcium will start to dissolve and may also release heat, which can cause the water to warm slightly. The reaction can be observed by the formation of a cloudy suspension due to the calcium hydroxide formed.
Step 2
Write the balanced equation for the reaction between magnesium and steam.
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Answer
The balanced chemical equation for the reaction between magnesium and steam is:
ightarrow ext{MgO}(s) + ext{H}_2(g)$$
Step 3
Suggest an explanation, in terms of their electronic configurations, why calcium is more reactive than magnesium.
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Calcium is more reactive than magnesium due to its electronic configuration. Calcium has the configuration 2.8.8.2, with two electrons in its outermost shell, whereas magnesium has 2.8.2, with only two electrons in its outermost shell as well, but it is in a higher period. This means that the outermost electrons in calcium are further from the nucleus and experience less effective nuclear charge. As a result, it is easier for calcium to lose its outer electrons compared to magnesium, making it more reactive.
Step 4
Calculate the empirical formula of calcium bromide.
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Answer
To find the empirical formula of calcium bromide:
Calculate the moles of calcium:
extMolesofCa=40extg/mol0.2extg=0.005extmol
Calculate the moles of bromine:
extMolesofBr=80extg/mol0.8extg=0.01extmol
Determine the simplest ratio:
extCa:Br=0.005:0.01=1:2
Thus, the empirical formula of calcium bromide is CaBr2.
