A student plots a graph of volume of CO₂ collected (cm³) against time (s) for two experiments: one using large marble chips and one using small marble chips, with all other variables identical. Which statement correctly describes the two curves at the start of the reaction?

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Question

A student plots a graph of volume of CO₂ collected (cm³) against time (s) for two experiments: one using large marble chips and one using small marble chips, with all other variables identical. Which statement correctly describes the two curves at the start of the reaction?

Accepted Answer

Both curves start at the same point and the small chips curve has a steeper initial gradient — Both experiments start at zero volume of gas, and both use the same mass of marble, so both curves end at the same total volume. However, small chips have a greater surface area, increasing collision frequency and thus the rate, so the small chips curve has a steeper initial gradient. The starting volume for both must be zero since no gas has been produced yet. The same mass does not mean the same rate — surface area is different. Larger particles do not move faster; rate depends on collision frequency at the surface.

Answer

Both curves have the same initial gradient because the same mass of marble is used

Answer

Both curves start at the same point and the small chips curve has a steeper initial gradient

Answer

The small chips curve starts at a higher volume than the large chips curve

Answer

The large chips curve has a steeper initial gradient because larger particles move faster

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