Difference Between Physical and Chemical Change

Thekey differencebetween physical and chemical change is thatphysical change merely changes the shape and size of the substance while chemical change produces altogether new substance.

许多人会想说改变是一种变化，以及为什么要在物理变化和化学变化之间做出区分的原因。但是，重要的是要了解这两种变化之间的差异，因为它们也影响了我们的生活和环境。

CONTENTS

1.Overview and Key Difference
2.What is Physical Change
3.What is Chemical Change
4.Side by Side Comparison – Physical and Chemical Change in Tabular Form
5.概括

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 ofmatterand thereactionsare 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

什么是化学变化？

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
• 煮鸡蛋
• 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.
Reversibility
Physical change is reversible	Chemical change is irreversible.
Speed of Change
Physical changes are fast.	Chemical changes are slow.
Properties
Only the state of matter changes while it still has the same properties.	The new substance formed has altogether different properties.

概括– 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.

Reference:

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

Image Courtesy:

1.’3956189266'by Stacy Spensley（CC由2.0）viaFlickr
2.’Large bonfire’ By Fir0002(CC BY-SA 3.0)viaCommons Wikimedia