# Ideal gas laws |Boyle’s law | Charles Law

Many gases at low-pressure, i.e. atmospheric pressure, and below atmospheric pressure for water vapor and some bar for gasses such as oxygen , argon and ,nitrogen are subjected to simple pressure, volume and temperature relations with sufficient accurate engineering purposes. Such gasses are referred to as “ideals.”

## Boyle’s law :

The law of Boyle is a gas law that states that the pressure exerted by a gas (of a given mass, sustained at a constant temperature) is inversely proportional to the volume it occupies. In other words, a gas’s pressure and volume are inversely proportional to each other as long as the temperature and gas quantity remain constant.

The relation between volume and pressure (at constant mass and temperature) can be mathematically expressed as follows:

**P ∝ (1/V)**

Where P is the pressure exerted by the gas and V is the volume occupied by it. This proportionality can be converted into an equation by adding a constant, k.

**P = k (1/V) **

** PV = k**

In Boyle’s Law, the product of pressure and volume at constant temperature is a constant for an ideal gas

## Charles Law :

Charles Law states that for an ideal gas the volume is proportional to the absolute temperature at constant pressure. The rule also states that when the pressure exerted on a sample of a dry gas is kept constant the Kelvin temperature and volume should be in direct proportion.

Charles law also sometimes called volume law provides a detailed account of how gas expands as the temperature increases. Conversely, as when temperature decreases it leads to volume decrease.

** V / T = Constant**

The laws of Boyle and Charles can be merged into the ideal equation for gases:

**PV = (a constant) x T**

**PV = nRT**

The constant ‘n’ is number of moles and R is the specific gas constant,