1. WARM UP
“We never touch people so lightly that we do not leave a trace.” – Peggy Tabor Millin
What does this mean to you?
How can you use this idea in your daily life at school?

2. The Big Bang Theory

3. Properties of Gases
Chemistry II

4. Gas Molecules All compounds can be in the gas state
Many need extreme temperature

5. Gas Molecules Some compounds are gases under “normal” conditions
Covalent compounds with weak intermolecular forces
O2, CO2, NO2, CH4, etc.

6. Characteristics of Gases
Change shape and volume
Highly compressible
Mix evenly and completely
Very low density

7. Pressure of a Gas Gases exert pressure Moving molecular fluid
Pressure from all sides

8. Pressure of a Gas Pressure in a system / reaction
Can measure pressure with a manometer
Unit: mmHg

9. Pressure of a Gas
Example:

10. Pressure of a Gas Atmospheric pressure From weight of a column of air
Measured with a barometer
Unit: mmHg

11. Pressure Measurements
Newtons (N)
Issac Newton
F = ma (force = mass x acceleration)
kg·m/s2

12. Pressure Measurements
Pascals (Pa) – the SI unit
Blaise Pascal
Pressure = force / area
N/m2

13. Pressure Measurements
Atmospheres (atm) – Equation unit
1 atm = x 105 Pa

14. Pressure Measurements
mmHg (a.k.a. torr) – Measurement tool unit
Evangelista Torricelli
760 mmHg = 1 atm

15. WRAP UP
Gases are _________ compressible and have a very _________ density.
Explain why these two properties are related.