A student produced this sketch of a quarry face - Edexcel - GCSE Chemistry - Question 4 - 2012 - Paper 1
Question 4
A student produced this sketch of a quarry face.
(a) The limestone shown was originally formed in layers. State what type of rock limestone is.
(b) Granite is an i... show full transcript
Worked Solution & Example Answer:A student produced this sketch of a quarry face - Edexcel - GCSE Chemistry - Question 4 - 2012 - Paper 1
Step 1
State what type of rock limestone is.
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Answer
Limestone is a sedimentary rock. It is formed from the accumulation of organic materials, minerals, and the remains of marine organisms in layers over time.
Step 2
Explain how the marble has formed above the granite.
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Answer
Marble has formed above the granite due to heat and pressure. When limestone (the original rock that transforms into marble) is subjected to intense heat and pressure, it undergoes metamorphism. This process alters its mineral composition and structure, leading to the formation of marble.
Step 3
Explain why the rock at X contained larger crystals than the rock at Y.
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Answer
The rock at X contained larger crystals than the rock at Y because X cools slowly compared to Y, which cools quickly. The slower cooling allows for the formation of larger mineral crystals, as there is more time for the crystals to grow before the rock solidifies.
Step 4
Complete the equation for this reaction.
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Answer
The complete equation for the decomposition of calcium carbonate is:
ightarrow ext{CaO} + ext{CO}_2$$
Step 5
Write the balanced equation for this reaction.
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Answer
The balanced equation for the reaction of calcium oxide with water is:
ightarrow ext{Ca(OH)}_2$$
Step 6
Explain why calcium hydroxide (slaked lime) is spread on fields.
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Answer
Calcium hydroxide is spread on fields to neutralize acidic soils. It reacts with the acids present in the soil, helping to improve soil quality and enhance crop growth by increasing the soil's pH level.
