1. AQA Physics Thermal Physics Section 2 Gas Laws

2. Boyle’s Law The pressure of a gas is inversely proportional to the volume it occupies when kept at constant temperature. (A change that occurs at a constant temperature is known as an isothermal change.) V1V1 V2V2 T T P2P2 P1P1

3. Boyle’s Law Boyle’s law can be represented graphically. p V T2T2 T1T1 A pressure verses volume graph is plotted opposite for two identical gases at different temperatures. (T 2 is greater than T 1 ) p 1/V T2T2 T1T1 A pressure verses 1/volume graph is plotted opposite for two identical gases at different temperatures. (T 2 is greater than T 1 )

4. Charles’ Law The volume of a gas is proportional to its temperature (in Kelvin) at constant pressure. (A change that occurs at a constant pressure is known as an isobaric change.) V1V1 V2V2 T1T1 T2T2 p p

5. Charles’ Law Charles’ law can be represented graphically. A volume verses temperature graph is plotted opposite for two identical gases at different pressures. (p 2 is greater than p 1.) V T p1p1 p2p2

6. Gay-Lussacs’ Law The pressure of a gas is proportional to its temperature (in Kelvin) at constant volume. V V T1T1 T2T2 P2P2 P1P1

7. Gay-Lusaacs’ Law Gay-Lusaacs’ law can be represented graphically. A pressure verses temperature graph is plotted opposite for two identical gases at different volumes. (V 2 is greater than V 1.) p T V1V1 V2V2

8. Gas Laws The gas laws can be combined to show that the expression: Is constant for a fixed amount (number of moles) of gas. V1V1 V2V2 T1T1 T2T2 P2P2 P1P1

9. The Ideal Gas Law A gas of n moles at a temperature (T) and a pressure (p), occupying a volume (V), obeys the following ideal gas equation: R is the molar gas constant. R = 8.31JK -1 mol -1

10. The Ideal Gas Law A gas of N entities at a temperature (T) and a pressure (p), occupying a volume (V), obeys the following ideal gas equation: k is the Boltzmann constant. k = 1.38x10 -23 JK -1