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Standard Temperature and Pressure

Key Stage 3


Room Temperature is around 20°C.

About Room Temperature

Room Temperature is used to describe when a substance has a particular state of matter.
When stating that Iron is a solid we assume the person stating it means at room temperature because that's the temperature humans are comfortable in. In reality Iron can be a solid, liquid or gas depending on the temperature.
The state of elements on the Periodic Table are given at room temperature.

Key Stage 4


Standard Temperature and Pressure is around 20°C and 101,000Pa.

About Standard Temperature and Pressure

Standard temperature or room temperature is around 20°C because that is the temperature humans are most comfortable in.
Standard pressure is around 101,000Pa of atmospheric pressure because that is the pressure on our bodies when we are at sea level.
Standard temperature and pressure is used to describe whether a substance is a solid, liquid or a gas under normal conditions.
Substances can change their state of matter depending on the temperature and pressure around them. So when stating something as a solid, liquid or gas it's important to note the temperature and pressure at which this is true.


Water is a liquid STP (At standard temperature and pressure). If the pressure is reduced to zero then water becomes a gas.
Oxygen is a gas STP. Increasing the pressure or decreasing the temperature of Oxygen can cause it to become a liquid.