Chemical Reactions: Introduction

A chemical change differs from a physical change because

Grilling some fish for dinner will change the composition of the fish. The chemicals in the raw meat become different chemicals.

State whether this is a chemical change.

Ice in a drink starts to melt. The ice turns from solid water into liquid water.

State whether this is a chemical change.

A deflated balloon has air blown into it until it is full. The balloon is now stretched and bouncy.

State whether this is a chemical change.

We look for the effects that chemical changes have on a changing substances.

Compared to a physical change, it can be much less obvious that a chemical change has occurred.

Select all indicators that can show that a chemical reaction has occurred.

A car rusts over time at the sea shore. The colour of the metal changes, and the metal slowly disappears. This process cannot be reversed.

Propose whether a chemical or physical change is occuring.

Two clear, colourless solutions are mixed together. When they are mixed, a yellow solid (precipitate) forms in the colourless solution.

Justify how you know that a chemical change has happened.