VOLUME AND TEMPERATURE: CHARLES’S LAW 13.1: Pgs

Jacques Charles ( )  First person to fill a balloon with hydrogen gas  Made the first solo balloon flight  His main discovery is shown in the graph…

Plots of V (L) versus T (°C) for several gases.  Volume increases when the temperature increases  Direct relationship, as T, V

Charles’s Law  Charles’s Law:  T is in Kelvins  CANNOT CHANGE the pressure or amount of gas It tells us that the volume of the gas is directly proportional to the temperature on the Kelvin scale

Plots of volume versus temperature  As we cool gases, they eventually liquefy  If we extend a straight line back, ALL lines reach zero volume at o C  This suggests that -273 o C is the lowest possible temperature

Absolute Zero and the Kelvin Scale  Lord Kelvin proposed a new temperature scale based on this discovery  Kelvin (K) scale: 1 K same size as 1 degree C, but zero point changed to -273 o C and became 0 K (not degrees) 260 o C becomes ___ K? 13K  0 K is lowest temperature theoretically possible  Absolute zero represents zero kinetic energy All motion stops theoretically

Example  A balloon inflated in a room at 24 o C has a volume of 4.00L. The balloon is then heated to a temperature of 58 o C. What is the new volume if the pressure remains constant?  If a sample of gas occupies 6.80L at 325 o C, what will be its volume at 25 o C if the pressure does not change.

Gay-Lussac’s Law  Studies the relationship between pressure and temperature  “The pressure of a gas is directly proportional to the Kelvin temperature if the volume remains constant”

Example  The gas left in a used aerosol can is at a pressure of 103 kPa at 25 o C. If this can is thrown onto a fire, what is the pressure of the gas when its temperature reaches 928 o C?  The pressure in an automobile tire is 198 kPa at 27.0 o C. At the end of a trip on a hot sunny day, the pressure has risen to 225 kPa. What is the temperature of the air in the tire? (Assume the volume has not changed.)