Fff 12-3 Charles Law

The relationship between temperature and volume

How Volume Varies With Temperature

• If we place a balloon in liquid nitrogen it shrinks: • So, gases shrink if cooled.

How Volume Varies With Temperature

• Conversely, if we heat a gas it expands • As in a hot air balloon.

Charles’s Law

• Charles’s Law: • As the temperature of a gas increases, • the volume increases proportionally, • provided that the pressure and amount of gas remain constant, • Formula = V1/T1 = V2/T2

• A sample of gas occupies 3.5 L at 300 K. What volume will it occupy at 200 K? V1 = 3.5 L, T1 = 300K, V2 = ?, T2 = 200K Using Charles’ law: V1/T1 = V2/T2 3.5 L / 300 K = V2 / 200 K V2 = (3.5 L/300 K) x (200 K) = 2.3 L

1. If a 1 L balloon is heated from 22°C to 100°C, what will its new volume be? V1 = 1 L, T1 = 22°C = 295 K V2 = ?, T2 = 100 °C = 373 K

V1/T1 = V2/T2,

1 L / 295 K = V2 / 373 K V2 = (1 L/295 K) x (373 K) = 1.26 L • Note the Temperature was converted to

Kelvin

• Show that gas Charles’ Law volume and Temperature are a direct proportion • Temperature goes up Volume goes up • Temperature goes down Volume goes down.

o

Kelvin / Celsius conversions (exact):

• Kelvin = o Celsius + 273.15 • o Celsius = Kelvin - 273.15