Gas

Kinetic Molecular Theory the tiny particles in all forms of matter are in constant motion

What is a gas?

Gas Elements

Properties of Gasses (determines why a gas behaves the way it does) Pressure Volume Amount Temperature

Pressure the force a gas exerts on the inside walls of its container

Pressure Measured in atmospheres (atm), pascals (Pa), millimeters Mercury (mmHg)

Volume the space of the container it is trapped in

Volume Measured in m³ or Liters

Amount amount of gas molecules in a given sample

Amount Measured in moles Convert mass to moles by dividing by molar mass

measured in units called Kelvin Temperature measured in units called Kelvin Useful in measuring very cold temperatures

Temperature Convert C to K by adding 273 The Kelvin scale starts at Absolute 0, which is -273°C.

Kelvin Practice Absolute zero is 0 K or -273°C Calculate the missing temperatures: 0°C = _____ K 100°C = _____ K 100 K = _____ °C -30°C = _____ K 300 K = _____ °C 400 K = _____°C 25 °C = _____ K 0 K = _____°C

The Gas Laws For a fixed amount of gas, a change in one variable (pressure, temperature, or volume) affects the other two

the relationship between pressure and volume of a gas Boyle’s Law the relationship between pressure and volume of a gas

What does this mean?

the volume of a gas is inversely proportional to its pressure Boyle’s Law the volume of a gas is inversely proportional to its pressure Irish Chemist Robert Boyle (1627-1691)

Inversely Proportional when one goes up, the other goes down pressure volume

Boyles law at work…

Constants Amount and temperature

Equation: P₁V₁ = P₂V₂

Boyle’s Law Illustrated

Boyle’s Law A gas has a volume of 3.0 L at 2 atm. What is the volume at 4 atm? 3.0 L x 2 atm = P₂ x 4 atm

PV = k Boyle’s Law Volume Pressure P.V P V 10.0 20.0 30.0 40.0 760.0 (mL) Pressure (mmHg) P.V 10.0 20.0 30.0 40.0 760.0 7600 380.0 7600 253.3 7600 190.0 7600 P V PV = k

PV Calculation (Boyle’s Law) A quantity of gas has a volume of 120 dm3 when confined under a pressure of 93.3 kPa at a temperature of 20 oC. At what pressure will the volume of the gas be 30 dm3 at 20 oC? P1 x V1 = P2 x V2 (93.3 kPa) x (120 dm3) = (P2) x (30 dm3) P2 = 373.2 kPa