Cambridge Secondary (7-9). Stage 9. MCE Science. Workbook - Unit 8: Rate of Reaction - Question 13

In this experiment, add 50 ml of dilute hydrogen peroxide (1.5 M) to a conical flask, then add 1 g of yeast. Quickly fit a stopper connected by a delivery tube to an inverted, water-filled measuring cylinder in a water trough. Collect oxygen over water and record its volume every 30 seconds. Wear safety goggles and gloves.

Why is it important to measure the volume of oxygen gas produced at regular intervals?