Solids, Liquids & Gases (OCR GCSE Combined Science A (Gateway)): Revision Note
Exam code: J250
Solids, Liquids & Gases
Solids & Liquids
In solids and liquids, the molecules are tightly packed together
The difference is, in a liquid, the molecules have enough energy to push past each other
As a result of this, the density of solids and liquids are roughly the same

The molecules in solids and liquids are tightly packed, giving them a high density
Gases
In a gas, the molecules are widely separated
As a result of this, gases have significantly lower densities than solids or liquids
At room temperature, the distance between molecules in a gas is roughly ten times (in each direction) the distance between molecules in a solid or liquid
As a result, the density of a gas is typically around one-thousandth (1/1000) of the density of a solid or liquid, for example:
The density of water is 1000 kg/m3
The density of air at sea level and room temperature is 1.3 kg/m3

The molecules in a gas are widely spaced, giving it a much lower density
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