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(a) Copper carbonate reacts with dilute nitric acid - Edexcel - GCSE Chemistry - Question 6 - 2021 - Paper 1
Question 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 the ... show full transcript
Worked Solution & Example Answer:(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 was sufficient acid present to react entirely with the copper carbonate.
Step 2
By what factor has the concentration of the hydrogen ions in the mixture changed?
Answer
To determine the factor of change in hydrogen ion concentration when the pH changes from 2 to 6, we use the formula:
The pH change is from 2 to 6, which is a change of 4 units. Since each pH unit represents a tenfold change in hydrogen ion concentration:
- A change of 4 units means the concentration of hydrogen ions decreases by a factor of:
Thus, the correct answer is 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 following steps should be followed:
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Evaporation: Heat the copper sulfate solution gently to allow the water to evaporate. This will concentrate the solution.
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Crystallization: Once the solution becomes saturated, remove it from the heat and allow it to cool slowly. As it cools, copper sulfate crystals will start to form.
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Separation: After the crystals have formed, filter the mixture to separate the crystals from the remaining solution.
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Drying: Finally, place the crystals on a clean surface (such as filter paper) to dry completely.