Photo AI
6 (a) Copper carbonate reacts with dilute nitric acid - Edexcel - GCSE Chemistry - Question 6 - 2021 - Paper 1
Question 6
6 (a) Copper carbonate reacts with dilute nitric acid. (i) During the reaction the copper carbonate powder completely disappears. State what can be deduced about th... show full transcript
Worked Solution & Example Answer:6 (a) Copper carbonate reacts with dilute nitric acid - Edexcel - GCSE Chemistry - Question 6 - 2021 - Paper 1
Step 1
During the reaction the copper carbonate powder completely disappears. State what can be deduced about the amount of acid used.
Answer
The complete disappearance of copper carbonate indicates that the dilute nitric acid was in excess. This means that there was enough acid present to react fully with the copper carbonate, suggesting that the amount of acid used exceeded the stoichiometric requirement for the reaction.
Step 2
By what factor has the concentration of the hydrogen ions in the mixture changed?
Answer
The pH scale changes logarithmically, so a change from pH 2 to pH 6 represents a change of 4 pH units. This corresponds to a factor of change in hydrogen ion concentration given by: ext{Factor} = 10^{ ext{(initial pH - final pH)}} = 10^{(2 - 6)} = 10^{-4} = rac{1}{10000} Thus, the concentration of hydrogen ions has changed by a factor of D × 1/10000.
Step 3
Describe what should be done to obtain copper sulfate crystals from this copper sulfate solution.
Answer
To obtain copper sulfate crystals from the copper sulfate solution, the solution should be allowed to evaporate slowly. As the water evaporates, the concentration of the copper sulfate solution will increase until it reaches saturation. At this point, crystals of copper sulfate will begin to form. The solution can be moderately heated to speed up the process, but it should not be boiled, as this can lead to the formation of anhydrous copper sulfate instead.