Does not create a colour change.

For example, water is colourless; when it freezes ice is also colourless ( occasionally it turns white, but that is due to air within it). Solid iodine is purplish. When it utrns to gas it is also purple.

Often creates a colour change.

Magnesium is shiny and grey. After it burns it becomes MgO, which is milky white.

Involves smaller amounts of energy.

When water condenses it releases heat, but that heat does not set fire to things.

Absorbs or releases larger amounts of energy.

When nitroglycerin explodes, its gases are not only hot but they exapnd rapidly and damage anything in its path.

An element undergoing a physical change will not experience an increase in mass.

A compound undergoing a physical change will not experience a decrease in mass.

If 50 g of iron are heated sufficiently, 50 g of liquid iron will be produced.

If 50 g of ice are melted 50 g of water will be produced.

An element undergoing a chemical change will experience an increase in mass if compared to the compound produced.

A compound undergoing a chemical change will experience an decrease in mass if compared to the element produced.

If magnesium is burnt, the ash collected will weigh more because it contains magnesium bonded to oxygen.

If 80 g CuO decompose, only 64 g of Cu will be left behind, because the oxygen breaks free from the compound.

If a gas escapes from a solution then it will have the same properties as those of the dissolved gas.

Carbon dioxide that bubbles out of 7-up was still carbon dioxide when it was dissolved in the soft drink.

If a solid precipitates from a solution, it will have the same properties as those of the dissolved solid.

For example: excess sugar accumulating at the bottom of an oversweetened cup of coffee.

If a gas escapes, it will have different properties from the substance that produced it.

Magnesium + hydrochloric acid = magnesium chloride + hydrogen gas. Hydrogen is flammable; hydrochloric acid is not.

If a solid forms in solution, it will have different properties from the substances that were dissolved.

Sodium chloride + silver nitrate = sodium nitrate + solid silver chloride.