Topic: Charles’ Law Do Now: If all of the flasks are the same in size, temperature, and contain the same number of particles, in which flask will they be moving the fastest? Which will have the greatest pressure?

Temperature Changes & Matter Solids & Liquids expand/contract as temperature changes usually very small change Gases show large volume changes with temperature changes

Balloons can expand & contract with the gas

Jacques Charles Balloonist 1787 did experiments showing how volume of gases depends on temperature

How do hot air balloons work?

Relationship between V and T Constant: Pressure & # moles are constant At high temp, gas particles move faster and collide with walls more often Pressure is constant, so volume has to increase

Data for Volume-Temperature 202 300 5 167 200 4 132 100 3 114 50 2 10 1 Volume (mL) Temperature (C) Trial

Charles’ Law: Graphically Plot V vs Kelvin T Straight line passing through 0rigin relationship between V & T is direct

Charles’ Law: Verbal volume of gas at constant pressure varies directly with its absolute temperature (note: when we’re talking about absolute temperature we mean Kelvin scale!!!!)

Charles’ Law: Mathematically V = k T V1 = V2 NOTE: Temperature must be converted to Kelvin!!!

Flash Back….what is the equation for Boyle? P 1V1 = P2V2 Is this a direct relationship?

Problem 1 150 mL of a gas at constant pressure Temperature increases from 20˚C to 40˚C What is the new volume? Step 1: Convert T1 and T2 to Kelvin Step 2: V1 = V2 becomes 150ml = V2 T1 T2 293K 313K Step 3: Rearrange and solve 313K x 150ml = V2 293K