How do we know a chemical change has happened?

Answer 1

You can tell if something is a chemical changes or a physical change.

Examples:

Question 1) Ice melting.

Answer 1) Physical change because nothing has changed just the shape of the ice. Reversing ice is easy.

Question 2) Wick on a candle changes colour from white to black.

Answer 2) Chemical change because it changes from clack to white and will be hard to reverse.

So if it is a chemical change taking place it hard to convert back or reverse. You can also tell by the change of colour.

Answer 2

A chemical change is indicated by the formation of new substances with different properties than the original substances. Signs of a chemical change include color change, formation of a precipitate, evolution of gas, or absorption/release of heat. These changes are often irreversible.

Answer 3

A new substance has formed