A Barbadian student investigated the reaction between marble chips and dilute sulfuric acid. She recorded the mass of the flask at regular intervals. Which observation indicates the reaction rate is decreasing over time?

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Question

A Barbadian student investigated the reaction between marble chips and dilute sulfuric acid. She recorded the mass of the flask at regular intervals. Which observation indicates the reaction rate is decreasing over time?

Accepted Answer

The mass of the flask decreases more slowly as time passes — Award 1 mark for recognising that a decreasing rate of mass loss indicates the reaction is slowing down as reactants are used up. C is incorrect — mass decreases (not increases) as CO₂ gas escapes. A is incorrect — more rapid bubbling would indicate an increasing rate. B is incorrect — constant temperature does not directly indicate reaction rate.

Answer

The temperature of the mixture remains constant throughout

Answer

The mass of the flask increases at a constant rate

Answer

The mass of the flask decreases more slowly as time passes

Answer

Bubbles are produced more rapidly as the reaction proceeds

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