1. Gases and Pressure – sec. 1
Objectives – sec 1
Define pressure, give unit of pressure, and describe how pressure is measured
State the standard conditions of temperature and pressure and convert units of pressure.
Use Dalton’s law of partial pressures to calculate the partial pressures and total pressures.

2. Gases and Pressure Kinetic molecular theory -
States that all particles of matter are in constant motion.
In this section we will be studying the implications of the kinetic-molecular theory of gases.

3. Gases and Pressure: Pressure and Force
Pressure – the force per unit area on a surface.
Pressure is dependent on three areas – the number of particles, the temperature, and volume
Pressure = force – in newtons
area – square units

4. Pressure and Force Pressure = 500 N = 1.5 N/cm2 325 cm2
Force is measured in newtons
Newton – is the force that will increase the speed of a one-kilogram mass by one meter per second each second the force is applied.
Pressure = force
area
Force = 500 N area =325 cm2
Pressure = 500 N = 1.5 N/cm2
325 cm2

5. Pressure and Force Area = 13 cm2 force = 500 N pressure =?
P = f P = 500N = 38.5 N/cm2
a cm2
Area = 6.5 cm2 force = 500N pressure =?
P = 500N = 77N/cm2
6.5 cm2

6. Pressure and Force
The atmosphere at sea level exerts a pressure equal to a 1.03 kg mass/cm2 or 10.1 N/cm2
Measuring Pressure –
In the 1600s Evangelista Torricelli – working with mercury, he found that mercury in a tube when inverted into a dish of mercury would stop falling around 760mm in length from the height of the mercury in the dish.