Question detail
Which technique is commonly used to test the purity of an organic solid?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
A-level practical endorsement and required practical activities
Question
- A. Thin-layer chromatography
- B. Titration
- C. Filtration
- D. Distillation
Answer
Thin-layer chromatography
Explanation
The correct option is Thin-layer chromatography. Thin-layer chromatography is the best answer because it directly supports the AQA A-Level Chemistry objective to required practical 10: prepare an organic solid and test its purity. This reasoning is anchored to A-level required practical activities in A-level practical endorsement and required practical activities, and it separates required practical from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.
Common mistake
Incorrect Calculation of Purity
Students often forget to convert the mass of the organic solid to moles before calculating purity, leading to incorrect results.
To calculate purity, use the formula: purity (%) = (mass of pure substance / total mass) x 100. First, convert the mass of the organic solid to moles using the formula: moles = mass / Mr. Then, substitute the values into the purity formula. For example, if you have 5 g of a substance with an Mr of 100 g/mol, first calculate moles: 5 g / 100 g/mol = 0.05 mol. If the mass of pure substance is 4 g, then purity = (4 g / 5 g) x 100 = 80%. Thus, the purity of the organic solid is 80%. Keep the correction anchored to A-level required practical activities and the objective: Required practical 10: prepare an organic solid and test its purity.
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