类别 全部 - chemical - changes - temperature - physical

作者:AA - 07TO 982485 Sir John A Macdonald Sr PS 18 天以前

101

Changes of matter

The transformation of matter can be categorized into physical and chemical changes. Physical changes, such as dissolving, freezing, melting, boiling, and chopping, alter the form of a substance without changing its chemical composition and are typically reversible.

Changes of matter

Changes of matter

Physical changes

Chopping
In this GIF, someone is using a knife to cut a cucumber, reducing the overall size of the cucumber
Decreasing the physical size of a substance, usually with something sharp.
Dissolving
This sugar cube is mixing with the water compeltely, creating a white sugar-water mixture
The act of a substance mixing with another to create a new mixture.
Freezing, melting and boiling
This diagram shows what happens to water when its frozen, melted and boiled.
These describe the exact temperature when matter changes state into a solid, liquid and gas.
These are changes to the form of a substance, but not the actual composition. These changes are always reversible in some way.

Matter makes up everything in the universe, and takes up space around us. Matter can undergo either physical or chemical changes. Read on to learn more!

Chemical changes

Colour change
The 2 purple and blue liquids turn yellow and pink when the substance is put in them, but more smoke is being created, indicating a chemical change
A colour change alone actually indicates a physical change only. However, if 2 substances are mixed and there's a colour change and a substance being formed, it counts as a chemical change.
Decomposition
The food in this GIF disintegrates and releases small matter particles (i.e sugars, oxygen, carbon dioxide).
When a substance breaks down into smaller products.
Precipitation
A solution from a solute and solvent, when separated, will form an un-mixable solid at the bottom of the container
When a substance is put in another substance with liquid properties, and the result is an insoluble mixture that sinks to the bottom of a container.
Forming bubbles/Fizzing
Soon after the Mento is put in the soda, the gas explodes out the bottle and bubbles form rapidly.
When a substance is put in another substance with liquid properties it can cause bubbles to form and a fizzing sound due to gas escaping the liquid.
Endothermic/Exothermic changes
Exothermic: Coal gives off energy when put in fire, causing it to make the fire burn more intensely.
Endothermic: In this GIF, the bread(specifically the yeast) absorbs the heat to make it rise and expand.
Refers to a chemical change where a substance either requires or gives off heat as a reaction to form chemicals.
When a substance creates a different substance with new chemical properties.