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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.
Answer
When a piece of calcium is dropped into water, it would be seen to fizz vigorously due to the rapid reaction with water. The reaction produces hydrogen gas which may be observed as bubbles. Calcium may also become submerged and the water can turn cloudy as calcium hydroxide is formed.
Step 2
Step 3
Suggest an explanation, in terms of their electronic configurations, why calcium is more reactive than magnesium.
Answer
Calcium is more reactive than magnesium due to its electronic configuration. Calcium has a configuration of 2.8.8.2, which means it has two electrons in its outer shell that can be lost during a reaction. In contrast, magnesium has a configuration of 2.8.2, with only two electrons in its outermost shell. Although both metals lose two electrons to form positive ions, calcium's lower ionization energy makes it easier for it to lose its outer electrons, making it more reactive.
Step 4
Calculate the empirical formula of calcium bromide.
Answer
To calculate the empirical formula of calcium bromide:
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Determine the moles of each element:
- Moles of Ca = mass / atomic mass = 0.2 g / 40 g/mol = 0.005 mol
- Moles of Br = mass / atomic mass = 0.8 g / 80 g/mol = 0.01 mol
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Calculate the simplest ratio of moles:
- Ratio of Ca : Br = 0.005 : 0.01 = 1 : 2
Therefore, the empirical formula of calcium bromide is CaBr₂.