The key difference between physical and chemical change is that physical change merely changes the shape and size of the substance while chemical change produces altogether new substance.
There are many who would be tempted to say that a change is a change and why to bother to make a distinction between physical and chemical change. But it is important to understand the differences between these two types of changes as they affect our lives and environment also.
What is Physical Change?
You must have observed changes in daily life too. Your fridge converts water into ice and your humidifier converts water into steam. Both are physical changes as they are merely changing the form of matter and the reactions are reversible. Ice readily changes into the water while steam also converts into water upon cooling. When you crush a can, you are merely causing a physical change in the shape and size of the can. Similarly, when you add salt or sugar to water to make solutions, it is a physical change as you can easily separate salt and sugar from the solutions to get original substances.
Examples of some physical changes include followings:
- Mixing sand and water
- Boiling water
- Cutting a paper into small pieces
- Chopping wood
- Melting an ice cube
What is Chemical Change?
A chemical change is a reaction in which matter converts into another type of matter. The reaction is irreversible and you cannot get back the earlier material. When the body of your car rusts, it is a chemical change (oxidation of iron to produce rust). Similarly, when you burn wood, you get ash and charcoal which have different properties from wood and you cannot reverse the process to get back wood. On the other hand, no matter how many small pieces of a paper you cut, it still remains paper and there are no changes in its properties; hence it is not a chemical change, but a physical change. But if you burn paper, what you get is carbon and not paper. Therefore a change, if it results in altogether different substances is a chemical change (while if the properties of the substance remain the same, it is called a physical change).
Examples of some chemical changes include:
- Burning wood
- Browning of food
- Cooking eggs
- Mixing acids with bases
- Brewing beer
What is the Difference Between Physical and Chemical Change?
Physical vs Chemical Change
|A type of change in which the form of matter is altered but one substance is not transformed into another.||A process where one or more substances are altered into one or more new and different substances.|
|Physical change is reversible||Chemical change is irreversible.|
|Speed of Change|
|Physical changes are fast.||Chemical changes are slow.|
|Only the state of matter changes while it still has the same properties.||The new substance formed has altogether different properties.|
Summary – Physical vs Chemical Change
Changes of matter can be either physical or chemical. The difference between physical and chemical change is that a physical change merely changes the shape and size of the substance while a chemical change produces altogether new substance.
1. Helmenstine, Anne Marie, Ph.D. “Physical Changes in Chemistry.” ThoughtCo, Apr. 11, 2018. Available here
2. Helmenstine, Anne Marie, Ph.D. “Chemical Change Definition in Chemistry.” ThoughtCo, Apr. 25, 2017. Available here