A student investigated how a change in concentration affects the rate of the reaction between zinc powder and sulfuric acid - AQA - GCSE Chemistry - Question 9 - 2021 - Paper 2

The lines become horizontal because the reaction has stopped, indicating that one or more reactants have been fully consumed.

The graph illustrates that the line corresponding to the 0.05 mol/dm³ sulfuric acid is less steep, indicating that it produces gas at a slower rate than the 0.10 mol/dm³ sulfuric acid.

At 80 seconds, the tangent to the curve on the 0.05 mol/dm³ line can be drawn to calculate the rate.

Let:

• The change in volume ($riangle y$) be taken from the graph at 80 seconds and the previous data point.
• The change in time ($riangle x = 80 seconds$). Then the rate can be calculated as:

$\text{Rate} = \frac{\triangle y}{\triangle x}$

The calculated value should be presented to 2 significant figures.

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