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Copper carbonate reacts with dilute nitric acid - Edexcel - GCSE Chemistry Combined Science - Question 4 - 2021 - Paper 1
Question 4
Copper carbonate reacts with dilute nitric acid. (i) During the reaction the copper carbonate powder completely disappears. State what can be deduced about the amou... show full transcript
Worked Solution & Example Answer:Copper carbonate reacts with dilute nitric acid - Edexcel - GCSE Chemistry Combined Science - Question 4 - 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 acid was in excess. This means that there was more acid present than was necessary to react with the copper carbonate.
Step 2
By what factor has the concentration of the hydrogen ions in the mixture changed?
Answer
The pH change from 2 to 6 represents an increase in the acidity level. The factor by which the hydrogen ion concentration changes can be calculated using the formula:
At pH 2, the concentration is:
At pH 6, the concentration is:
Thus, the factor of change is:
rac{0.01}{0.000001} = 10^4 ext{ or } 10000
Therefore, the correct answer is D × 1/10000.
Step 3
Using different reactants, a solution of copper sulfate was prepared. 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, you should perform the following steps:
- Evaporation: Heat the copper sulfate solution gently to evaporate some of the water. This will concentrate the solution.
- Cooling: Allow the concentrated solution to cool slowly. As the solution cools, copper sulfate will start to crystallize out.
- Filtering: Once crystals have formed, filter the mixture to separate the crystals from the remaining solution.
- Drying: Finally, dry the copper sulfate crystals by placing them on a filter paper or in a warm, dry environment.