2 (a) (i) The main compound in limestone is calcium (calcium carbonate) ............................................. - AQA - GCSE Chemistry - Question 2 - 2015 - Paper 1
Question 2
2 (a) (i) The main compound in limestone is calcium (calcium carbonate) .............................................. .
2 (a) (ii) The reaction to produce calcium ... show full transcript
Worked Solution & Example Answer:2 (a) (i) The main compound in limestone is calcium (calcium carbonate) ............................................. - AQA - GCSE Chemistry - Question 2 - 2015 - Paper 1
Step 1
2 (a) (i) The main compound in limestone is calcium
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Answer
The main compound in limestone is calcium (calcium carbonate).
Step 2
2 (a) (ii) The reaction to produce calcium oxide from limestone is thermal
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Answer
The reaction to produce calcium oxide from limestone is thermal (thermal decomposition).
Step 3
2 (a) (iii) Calcium hydroxide is produced when calcium oxide reacts with
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Answer
Calcium hydroxide is produced when calcium oxide reacts with water.
Step 4
2 (a) (iv) Calcium hydroxide is used to neutralise acids because it is an
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Answer
Calcium hydroxide is used to neutralise acids because it is an alkali.
Step 5
2 (b) (i) One of the points is anomalous.
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Answer
To illustrate this, draw a straight line through the first, second, and fourth data points, and a separate straight line through the last four points. This will help visually identify the anomalous point.
Step 6
2 (b) (ii) Describe one way the students could improve the method.
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Answer
One way to improve the method is to repeat the experiment for each mass of aggregate. This way, a mean or average value can be calculated for the force needed to break the concrete beam at each aggregate mass, which will lead to more accurate data points.
Step 7
2 (b) (iii) What force is needed to break a concrete beam containing no aggregate?
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Answer
Referencing the graph, the extrapolated line indicates that the force needed to break a concrete beam containing no aggregate is approximately 34-40 newtons.
Step 8
2 (b) (iv) Explain why the student's conclusion is not completely correct.
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Answer
While the force needed to break a concrete beam generally increases with the mass of the aggregate, the graph suggests that it starts to decrease after a certain point (around 400 grams). This means that increasing the mass beyond this point does not always yield increased strength in the concrete beam, contradicting the student's statement.
