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Purity and separating mixtures

Purity and separating mixtures

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Question 18

A student synthesises a sample of benzoic acid and wants to assess its purity by measuring its melting point, TexpT_{\text{exp}}Texp​ (in ∘C^\circ\text{C}∘C). The literature melting point of pure benzoic acid is 122.4 ∘C122.4\ ^\circ\text{C}122.4 ∘C.

Which equation correctly represents the percentage difference between the student's experimental value and the literature value?

A

Percentage difference=100×Texp−122.4Texp\text{Percentage difference} = 100 \times \frac{T_{\text{exp}} - 122.4}{T_{\text{exp}}}Percentage difference=100×Texp​Texp​−122.4​

B

Percentage difference=100×Texp−122.4122.4\text{Percentage difference} = 100 \times \frac{T_{\text{exp}} - 122.4}{122.4}Percentage difference=100×122.4Texp​−122.4​

C

Percentage difference=Texp−122.4122.4\text{Percentage difference} = \frac{T_{\text{exp}} - 122.4}{122.4}Percentage difference=122.4Texp​−122.4​

D

Percentage difference=100×122.4−TexpTexp\text{Percentage difference} = 100 \times \frac{122.4 - T_{\text{exp}}}{T_{\text{exp}}}Percentage difference=100×Texp​122.4−Texp​​

Markscheme

Purity and separating mixtures Questions

  1. GCSE
  2. /Chemistry
  3. /Purity and separating mixtures

46 exam-style questions on OCR GCSE Chemistry Purity and separating mixtures. Each one has a worked solution and a mark scheme showing where the marks go.

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