This question is about reactions of ethanoic acid and the analysis of salts - AQA - GCSE Chemistry - Question 1 - 2016 - Paper 3
Question 1
This question is about reactions of ethanoic acid and the analysis of salts.
1 (a) Figure 1 shows the apparatus used to investigate the reaction of ethanoic acid wi... show full transcript
Worked Solution & Example Answer:This question is about reactions of ethanoic acid and the analysis of salts - AQA - GCSE Chemistry - Question 1 - 2016 - Paper 3
Step 1
1 (a) (i) Describe a change that would be seen in each test tube.
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Answer
In test tube 1, there will be fizzing or effervescence due to the reaction between ethanoic acid and calcium carbonate, leading to the formation of carbon dioxide gas. The limewater will turn cloudy or milky as calcium carbonate forms because of the precipitate. In test tube 2, there is no reaction as there is no acid present.
Step 2
1 (a) (ii) Complete the displayed structure of ethanoic acid.
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Answer
The completed structure of ethanoic acid is as follows:
H O
| //
H-C-C
| \
H O-H
The hydroxyl group (-OH) must be attached to the carbon.
Step 3
1 (a) (iii) Ethanoic acid is a carboxylic acid.
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Carboxylic acids react with alcohols in the presence of an acid catalyst to produce pleasant-smelling compounds called esters.
Step 4
1 (b) Complete the table of results.
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Answer
The results of testing each solution and water with silver nitrate and barium chloride are:
Solution
Test with silver nitrate
Test with barium chloride
Potassium chloride solution
no change
white precipitate
Calcium nitrate solution
no change
no change
Ammonium sulfate solution
no change
no change
Water
no change
no change
Step 5
1 (c) (i) Complete the following sentences.
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Answer
The flame colour for potassium ions is lilac.
The flame colour for calcium ions is red.
Step 6
1 (c) (ii) Give one reason why a flame test would not show the presence of both potassium and calcium ions in a mixture.
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Answer
The flame colours are masked or changed by each flame colour, making it difficult to identify both ions simultaneously.
