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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 the copper carbonate powder indicates that the amount of dilute nitric acid used is in excess. This means that there is enough acid present to react completely with the copper carbonate, leading to the formation of copper nitrate, water, and carbon dioxide.
Step 2
By what factor has the concentration of the hydrogen ions in the mixture changed?
Answer
The change in pH from 2 to 6 indicates an increase in the acidity level. The pH scale is logarithmic, meaning that each whole number change on the scale represents a tenfold change in hydrogen ion concentration. Therefore, the change in pH from 2 to 6 corresponds to a factor of , which indicates that the concentration of hydrogen ions has decreased by a factor of 10,000.
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, one should:
- Evaporate the solution: Gently heat the copper sulfate solution to evaporate some of the water, concentrating the solution.
- Allow crystallization: After evaporation, allow the concentrated solution to cool undisturbed. As it cools, copper sulfate crystals will start to form.
- Filter the crystals: Once crystals have formed, filter the solution to separate the solid copper sulfate crystals from the liquid.
- Dry the crystals: Place the collected crystals on a dry cloth or filter paper to remove any remaining water.