The document discusses the processes of melting, boiling, freezing and condensation. It explains that during these state changes, heat is absorbed or released in the form of latent heat, causing the temperature to remain constant. Impurities affect the freezing/melting and boiling points of substances by lowering or raising the temperature at which these state changes occur. Pressure also influences state changes, with higher pressure lowering melting/boiling points.

1. MELTING AND BOILING SEC 3 PHYSICS

5. Changes in States melting Boiling CONDENSATION FREEZING Gain in heat Loss in heat Solid Gas Liquid

8. The Temperature-time Graph temperature time This part of the graph shows a constant temperature which means this is when the substance is changing state

11. Effect of Impurities on Freezing Point The reverse situation would be true. (When melting.) A (no salt added) B (salt added) Ice cube A would melt at 0 o C. But B would melt(turn into liquid) at a temperature even lower.