A convenient and more scientific way to illustrate Boyle’s law is to plot the values of pressures and volumes of a given mass of a gas at constant temperature. The pressure-volume curves thus obtained at constant temperature are called isotherms. The graph of pressure, P versus, V volume of a gas at different temperatures is as shown below:

Charles’ law can be explained with the help of a graph. The plot of volume versus temperature at constant pressure are called isobars. When volume of fixed mass of a gas is plotted with temperature at different constant pressures, we get straight line in each case. On extending these lines to zero volume, all these intercept the temperature axis at - 273 . 15 ° C , however, these all have different slopes at different pressures as shown below.

Gay-Lussac’s law can be explained with the help of a graph. The plots of pressure versus temperature at constant molar volumes of a gas are called isochores. Pressure versus temperature graph of a gas is as shown below: