Question detail
Describe the steps you would follow to obtain a pure dry sample of sodium chloride from a reaction between sodium carbonate and hydrochloric acid.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Reactions of acids
Question
Describe the steps you would follow to obtain a pure dry sample of sodium chloride from a reaction between sodium carbonate and hydrochloric acid.
Answer
First, add an excess of sodium carbonate to a measured volume of hydrochloric acid and stir until the reaction stops, forming sodium chloride and water. Next, filter the mixture to remove the excess solid carbonate. Then evaporate the filtrate in a clean beaker until all the liquid has boiled off, leaving a solid residue. Finally, dry the residue in a drying oven or desiccator to remove any remaining moisture, giving a pure dry sample of sodium chloride.
Explanation
The answer demonstrates knowledge of the practical stages: reaction, filtration, evaporation, and drying, all of which are required to produce a pure dry salt. It tests understanding of the purpose of each step and the correct sequence, matching the learning objective.
Common mistake
Common Mistake in Salt Preparation
Students often forget to add the insoluble solid in excess when preparing a soluble salt, leading to incomplete reaction and impurities in the final product.
Always add the insoluble solid in excess to ensure that all the acid reacts and to filter out any unreacted solid, resulting in a pure dry sample of the soluble salt.
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