1. 1. Pressure is defined as the force per unit area on a surface. 2. The SI Unit for force is the newton (N). A newton is the Force that will increase The speed of a 1-kg Mass by one meter/sec Each second the force Is applied! 3.The atmosphere exerts pressure. It Contains 78% nitrogen, 21% oxygen, and 1% other gases, like argon and carbon Dioxide.

2. 4.Atmospheric pressure is the sum of the individual pressures of the Gases in the atmosphere. Why do your ears pop when your Flying in a plane? 1.A barometer is a device used to measure atmospheric pressure. The first barometer was developed by Evangelista Torrricelli (early 1600s). Torricelli found that mercury would reflect the pressure of air by dropping to a height of 760 mm everytime.

3. 2.A manometer can be used to measure the pressure of an enclosed gas sample. 1.mmHg “millimeters of mercury”: used in a barometer. Measures the Height of mercury in a column. (aka “Torr”) 2. Pressure can be measured in terms of atmospheres. One atmosphere Of pressure is known as 1 atm. (It’s equivalent to 760 mmHg.) 3.Pascal: defined as the pressure exerted by force of one 1 Newton On an area of a m 2. 1 atm is equivalent to 1.01325 X10 5 Pa (101.325 kPa).

4. 4.Standard Temperature and Pressure (STP) mean 1 atm of pressure and 0°Celsius. 1.This law states that the total pressure of a gas mixture is the sum of the partial Pressure of the component gases. T 123

5. 1.Gases in the lab are often collected over a water sample, so the gas Pressures involved are composed of the gas itself and water vapor pressure. 2.The formula for gas collection over water looks like this: atm gasH2OH2O

6. 1.Robert Boyle discovered in 1662 that gas pressure and volume are mathematically related. PV = k Volume of a gas is inversely related to Pressure of a gas at constant temperature. Direct vs. Inverse??? This is an inverse relationship…

7. 1.Gay-Lussac noticed that at constant temperature and pressure, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers. What’s the ratio? 1.He said “equal volumes of gases at the same temp. and pressure contain equal numbers of molecules.” 2. V = kn

8. 1.The volume occupied by one mole of a gas at STP.