This Science video introduces teachers to an engaging investigation into irreversible changes, where pupils explore how combining vinegar and bicarbonate of soda produces carbon dioxide gas. In this lesson, pupils will investigate whether the quantity of vinegar affects the amount of gas produced. Before the lesson, prepare ten bottles with measured amounts of vinegar and ten balloons filled with excess bicarbonate of soda. Store the bottle-and-balloon pairs in five trays.

This video is part of Kapow Primary’s Science scheme – gas. It supports teachers in demonstrating how gas is produced during a chemical reaction. Carefully attach each balloon to its bottle, making sure no air escapes and the bicarbonate stays inside the balloon. Begin the reaction by tipping the balloon upright to release the powder into the vinegar. As gas forms, the balloon inflates. Once fully expanded, tie off and label each balloon, starting with 50ml. Pupils then measure balloon circumference using string and a ruler to compare gas volumes. The aim is to observe: the more vinegar used, the more gas is produced, shown by a larger balloon circumference.

Science, Upper key stage 2, Year 5, Materials: Properties and changes, Lesson 6: Irreversible changes: Mixing