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6.1 Rate of reaction

6.1 Rate of reaction

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Question 5

A student investigated how the concentration of dilute nitric acid affects the rate of its reaction with sodium thiosulfate solution using a disappearing cross method.

During the investigation, the student:

  1. Measures 125 cm3125\text{ cm}^3125 cm3 of sodium thiosulfate solution of a fixed concentration into a conical flask.
  2. Places the flask over a paper sheet marked with a black cross.
  3. Adds 15 cm315\text{ cm}^315 cm3 of dilute nitric acid of a specific concentration.
  4. Immediately starts a stopwatch and measures the time taken for the sulfur precipitate to obscure the cross from view.
a.

Explain why a 100 cm3100\text{ cm}^3100 cm3 conical flask is unsuitable to use in this method.

[2]
b.

Identify the independent variable and the dependent variable in this investigation.

[2]
c.

The table below shows the results of the experiment using different concentrations of nitric acid:

Concentration of nitric acid (mol/dm3\text{mol/dm}^3mol/dm3)Time taken for cross to disappear (seconds)
0.2180
0.492
0.661
0.845

Which concentration of nitric acid has the highest rate of reaction? Explain how the data shows this.

[2]
Markscheme

6.1 Rate of reaction Questions

  1. GCSE
  2. /Chemistry
  3. /6.1 Rate of reaction

26 exam-style questions on AQA GCSE Chemistry 6.1 Rate of reaction, covering 6.1.1 Calculating rates of reactions, 6.1.2 Factors which affect the rates of chemical reactions, 6.1.3 Collision theory and activation energy, and 6.1.4 Catalysts. Each one has a worked solution and a mark scheme showing where the marks go.

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