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2025 O Level Chem P1 Q1 — Rate of Reaction Solution

Rate of Reaction 2025 O Level Pure Chemistry · Paper 1 · Q1

Question

To determine the rate of reaction, a scientist measures the volume of gas produced from the reaction between the acid and the reacting solid in one minute. The total volume of gas produced is expected to be between 30 cm³ and 40 cm³. The diagram shows part of the set-up. The following additional pieces of apparatus are available: a 50 cm³ burette; a 50 cm³ pipette; a 50 cm³ measuring cylinder; a 50 cm³ gas jar. Which pieces of apparatus could be added to the set-up to collect the gas and measure its volume? Question diagram

Question diagram

Aall four pieces of apparatus
Bthe burette and the measuring cylinder only
Cthe burette, the measuring cylinder and the pipette only
Dthe gas jar only

Correct answer: B

Video Solution

Explanation

Answer: B. The gas volume is expected to be 30–40 cm³, so a 50 cm³ burette or a 50 cm³ measuring cylinder are both suitable. The pipette only delivers a fixed volume (not a measurement of an unknown), and a gas jar isn't a measuring vessel.

Both burette and measuring cylinder can measure gas collected over water — burette by reading the volume scale, measuring cylinder by inverting into a trough. Either works.

The pipette (A and C) is for liquid transfer at one fixed volume; it cannot measure an unknown gas volume. The gas jar (A and D) collects gas but doesn't have a graduated scale to read the volume. Only the burette and measuring cylinder give a numerical reading suitable for this experiment.

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