# What are the units used for the ideal gas law?

##### 1 Answer

The equation for the Ideal Gas Law is:

#### Explanation:

On the whole, this is an easy equation to remember and use.

The problems lie almost entirely in the units.

**SI units**

**Pressure, #P#**

Pressure is measured in pascals (

Be careful if you are given pressures in kilopascals (

The bar is “almost” an SI unit.

**Volume, #"V"#**

This is one place for you to go wrong when you use the Ideal Gas Law.

That's because the SI base unit of volume is the cubic metre (

Thus, if you are inserting values of volume into the equation, you first have to convert them into cubic metres.

Number of moles,

This is easy, of course — the units are

**The gas constant, #R#**

You will usually be given the value for

The SI value for

The temperature,

The temperature has to be in kelvins.

Don't forget to add 273.15 if you are given a Celsius temperature.

**ALWAYS** make sure that the units you use for

**Non-SI units**

The major difference will be that the pressure is given in atmospheres or millimetres of mercury or bars or millibars, and volume may be in litres or millilitres.

If you have to convert from other pressure measurements:

The most common combination is to have pressure in atmospheres or bars and the volume in litres.

For these combinations, the most convenient values of

Again, **ALWAYS** make sure that the units you use for