Chemical changes
Acids, alkalis and the pH scale
The pH scale measures the acidity or alkalinity of a solution. Acids and bases have a wide variety of uses and can react together in neutralisation reactions.
Chemical reactions
Chemical reactions always form new substances. A change in colour, temperature or production of a gas or solid are all indicators of chemical reactions. Temperature, particle size and presence of a catalyst will all affect the rate of a reaction.
Video playlist
Conservation of mass in chemical reactions. Video
The concept of conservation of mass in chemical reaction using two examples.