Acid and Bicarbonate of Soda - Teacher Explanation

Welcome to lesson 5.7, where we delve into the irreversible changes involving acid and bicarbonate of soda within the Year 5 unit on properties and changes of materials. This lesson aligns with the National Curriculum's requirement for pupils to understand that certain changes lead to the creation of new materials and are typically not reversible. Such changes include those associated with burning and the reaction between bicarbonate of soda and acid. For safety, it is imperative that pupils wear protective goggles during practical activities, keep their chairs tucked in, stand on their feet, tie back long hair, and ensure no bags obstruct walkways. Given that the chemicals used, such as vinegar and bicarbonate of soda, can irritate the skin, wearing safety gloves is advised, especially for those with skin conditions. The lesson also presents cross-curricular opportunities, allowing pupils to explore the role of acid in etching, graph production, and the historical significance of acids in creating the first battery.

The practical component of the lesson involves classifying substances as acids, neutral, or alkaline using a range of safe household items and indicator papers. Pupils will learn to use the pH scale to determine the acidity or alkalinity of substances like vinegar, cola, and water. Another key experiment teaches pupils how to neutralize an acid, using vinegar and bicarbonate of soda—an important concept in the medical industry for treating conditions like heartburn. The lesson further investigates the reaction between acids and bicarbonate of soda, producing carbon dioxide gas, and explores the concept of endothermic reactions through the mixing of citric acid and bicarbonate of soda with water. This comprehensive lesson aims to provide pupils with a thorough understanding of chemical reactions and their practical implications, ensuring an engaging and educational experience.