3. Properties of gases No definite shape- it fills its container No definite shape- it fills its container Compressible- with increased pressure. Compressible- with increased pressure. Low density- molecules are far apart Low density- molecules are far apart - intermolecular attractions are ignored Diffusion- molecules can randomly spread out. Diffusion- molecules can randomly spread out.

4. Ideal gas Theoretical description of gases Theoretical description of gases disregard the volume of the molecule itself disregard the volume of the molecule itself disregard any attractive force between molecules disregard any attractive force between molecules Real gases stray from ideal gases at low temperatures and high pressures. Real gases stray from ideal gases at low temperatures and high pressures.

5. At STP, all gases have a volume of 22.4L. What happens when the temperature or pressure change? As temperature increases, volume increases. Charles Law: The volume of a quantity of gas, held at a constant pressure, varies directly with the Kelvin temperature. V1 = V2V1 = V2V1 = V2V1 = V2 T 1 T 2 at constant pressure T 1 T 2 at constant pressure The temperature must be in Kelvin!

6. Directly proportional

7. A gas collected at 58˚C has a volume of 225ml. What volume will it occupy at standard temperature, if pressure remains constant? First change all temperatures to Kelvin. 58 + 273 = 331K The temperature is falling, so the volume will do what? Decrease!

8. The original volume must be multiplied by a fraction <1. 225ml x 273K = 186 ml 331K 331K V1V1 T1T1 = V2V2 T2T2 x T 2 T 2 x

9. Boyles Law As pressure increases, volume decreases. As pressure increases, volume decreases. Temperature must be constant. Temperature must be constant. P 1 V 1 =P 2 V 2 P 1 V 1 =P 2 V 2

10. A sample of oxygen gas at.947 atm has a volume of 150. ml. What would its volume be at.987 atm, if the temperature stays constant? P 1 =.947 atm V 1 = 150. ml P 2 =.987 atm V 2 = ? P 1 V 1 = P 2 V 2 (.987 atm) V2V2V2V2 (150. ml) (.947 atm) = 144 ml = V 2