Ph.D.,U.C.Santa Cruz
Teaching at a top-ranked high school in SF
She teaches general and chemistry at a top-ranked high school in San Francisco. Prior to that, she lead and published a number of research studies and lectured at SF State University.
Changes in matter can be classified as either physical or chemical, like matter properties. Physical changes include changes in physical appearance but not composition. All changes in state of matter are physical changes. Chemical changes involve changes in chemical composition and require chemical reactions.
So let's continue talking about matter and so remember again that the law of the conservation of matter is that matter is neither created nor destroyed. So let's kind of discuss some of the changes that can occur in matter.
So the changes can be classified either as physical changes or as chemical changes. So very simply, a physical change in matter is when a substance changes its physical appearance but not its composition. And all changes of state are physical changes. Some of the changes of state I'm talking about whether something is a gas or solid or a liquid. So an example of a physical change would be the evaporation of water where you have water going from being a liquid to being a gas. Right, so the state has changed, the way that it looks more or less has changed but it's still composed of water molecules.
Then on the other hand you can have a chemical change which is in essence a chemical reaction, so that's when your substance is transformed into a chemically different substance and a good example of that is plants using carbon dioxide and water to form the sugar glucose. And that is changes in matter.
