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Use of apparatus and techniques

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123
Question 2

An impure sample of a solid organic compound, such as benzoic acid (melting point 122 ∘C122\ ^\circ\text{C}122 ∘C), is purified by recrystallisation and then dried.

Which of the following statement(s) about this process is/are true?

  1. A pre-heated funnel and fluted filter paper are used during hot filtration to prevent the organic product from crystallising in the funnel.
  2. To dry the purified crystals quickly, they should be placed in an oven set to a temperature of 130 ∘C130\ ^\circ\text{C}130 ∘C.
  3. Before turning off the water tap of the vacuum pump after suction filtration, the flask must be disconnected from the pump to prevent water from sucking back into the flask.

A 1, 2 and 3

B Only 1 and 2

C Only 1 and 3

D Only 2 and 3

A

1, 2  and \text{ and } and  3

B

Only \text{Only }Only  1  and \text{ and } and  2

C

Only \text{Only }Only  1  and \text{ and } and  3

D

Only \text{Only }Only  2  and \text{ and } and  3

Markscheme

Use of apparatus and techniques Questions

  1. A Level
  2. /Chemistry
  3. /Use of apparatus and techniques

5 exam-style questions on OCR A A Level Chemistry Use of apparatus and techniques. Each one has a worked solution and a mark scheme showing where the marks go.

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