Gas Equations
An ideal gas is a hypothetical gas whose volume varies in proportion to
its temperature and in inverse proportion to its pressure. For a gas to be an ideal
gas, as opposed to a real gas, its particles must follow certain rules:
Lack of intermolecular forces. Gas molecules must neither repel or attract
each other.
Elastic collisions. The only interaction between gas molecules are elastic
collisions. No energy is lost when particles collide against each other or against
the surface of the container so that kinetic energy remains constant.
Zero particle volume. Individual gas particles are so small in comparison to the
empty space between them, that their volume is negligible.
No gas can behave exactly like an ideal gas but the lower their intermolecular forces,
the more they can approach ideal behaviour. Nobel gases for examples, have very
low intermolecular forces and hence approach ideal behaviour.
At room temperatures and pressures, many of the gases we care about can be
assumed to behave ideally.
Finding the number of moles (n) of a gas
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The ideal gas equation can be used to calculate the volume of one mole of gas
at any temperature and pressure
Volume of a mole of gas at room temperature and pressure is 24 dm3 - one
mole of sulphur dioxide gas has the same volume as one mole of hydrogen gas
Unit conversions for the Ideal gas Equation
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Remember to convert the SI units when using the ideal gas equation
Finding the relative molecular mass of a gas
If you know the number of moles present in a given mass of gas, you can find the
mass of one mole of gas and this tell us the relative molecular mass
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