2Types of Changes Matter can change in one of two ways. Physical change – This is a change in which no new substance is produced. Eg. Melting, freezing, dissolving, breaking things, etc… These changes are “usually” easy to reverse.
3Chemical Changes. This is a change when one or more new substances are produced. Eg cooking, rusting, burning, etc… The new substances have properties that are very different from the original materials. (Compare a pile of ashes with the pile of wood that it came from)
4Indicators of a Chemical Change Heat is produced or absorbed. (it gets hotter or colder)A new substance is produced. (burning always produces water vapour and carbon dioxide.There may be an unusual change in color.A gas is produced. (May be bubbles)
55. A precipitate may form. (a semi-solid substance in the bottom of a liquid) The change is difficult to reverseThe starting materials are used up.Not all of these indicators has to be present but usually, several are.