What is the difference between a physical change and a chemical change?
Hey guys, in this question were asked to tell the difference between a physical change and a chemical change. Now in a physical change we're going to say our substance undergoes a change in appearance but its chemical composition stays the same, now in a physical change it usually means a change in the state of the compound so you're going between a solid, a liquid and gas you're going between these different things, OK? So, these are physical changes and we can talk about water, water as a solid, water as a liquid, water as a gas in every different state it's still water it's just changing the state that it's in. Now in a chemical change, a chemical change means that the appearance of the compound changes with a change in its chemical composition so for example we could have calcium solid reacts with oxygen in our environment and becomes calcium oxide. Here calcium was by itself and then O2 is by itself then they became something entirely new and different it's no longer calcium and oxygen by themselves they combine together to form calcium oxide so chemically it's very different and because the chemical composition changes that means that the way it reacts will change as well, so remember a physical change is just really a change in the state of the substance between solid, liquid and gas or as a chemical change result in a totally new compound with possibly new chemical properties.