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 calci... 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 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 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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Calcium hydroxide is used to neutralise acids because it is an alkali.
Step 5
2 (b) (i) Complete the graph in Figure 3 by drawing two straight lines of best fit.
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Answer
To complete the graph, draw a straight line through the first, second, and fourth points. Then, draw a straight line through the last four points.
Step 6
2 (b) (ii) Describe one way the students could improve the method so that their results are more accurate for each graph point.
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One way the students could improve their method is to repeat the experiment for each mass of aggregate used. This would allow them to calculate a mean or average value for each mass.
Step 7
2 (b) (iii) What force is needed to break a concrete beam containing no aggregate?
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Answer
To determine the force needed to break a concrete beam with no aggregate, refer to the graph and extrapolate the line to the y-axis. The correct force value can be read from the graph.
Step 8
2 (b) (iv) Use values from the graph to explain why the student's conclusion is not completely correct.
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The student's conclusion is partially correct. Initially, the force needed to break a concrete beam increases with the mass of aggregate, but it begins to decrease beyond a certain point. Notably, at 400g, the impact of additional aggregate shows that more weight does not always equate to increased strength.
