Difference between revisions of "Ch5 Lec 1"
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The most common gas pressure unit is a Pascal (Pa), but most of you are more familiar with an "atmosphere" (atm). A Pa is equal to 1 Newton of force/1 square meter. The column of air stilling on top of your head right now is exerting ~ 1 atm or 101,325 Pa. Apparently a Pa is a very small unit, so we often use kiloPascals (kPa) and not Pa. | The most common gas pressure unit is a Pascal (Pa), but most of you are more familiar with an "atmosphere" (atm). A Pa is equal to 1 Newton of force/1 square meter. The column of air stilling on top of your head right now is exerting ~ 1 atm or 101,325 Pa. Apparently a Pa is a very small unit, so we often use kiloPascals (kPa) and not Pa. | ||
::1 atm = ~ 101 kPa | ::1 atm = ~ 101 kPa | ||
| − | + | Additionally, we use other units for pressure as well that are based on a physical observation. If you had a u-shaped tube and no pressure was exterted on one side and some pressure was exerted on the other side, then you could measure the pressure as a distance a liquid inside the tube has moved. | |
| + | :[[File:Screen Shot 2020-03-26 at 3.49.28 PM.png|600px]] | ||
Another fun set of demos/discussion about air pressure: | Another fun set of demos/discussion about air pressure: | ||
Revision as of 20:49, 26 March 2020
Solutions Review...watch this "Crash Course" video (don't worry about taking notes).
Chapter 5: Gases
Section 5.1: Substances that exist as gases
- READ Intro and this section
Take home points:
- - Air is 78% N2, 21% O2, 1 % other
- - Many elements exists as gases, H2, N2, O2, halogens and the noble gases.
- - There are other molecular substances that exist as gases, HCl, CO, CO2, NH3 (ammonia), CH4 (methane), NO2, SO2, H2S.
- - Gases:
- - fill the volume of space that exist in,
- - are compressible,
- - when 2 gases are mixed, they will mix together to make a homogenous mixture,
- - have a density (g/mL), but much lower than a solid or liquid.
Section 5.2: Pressure of a gas
READ this section...
Additional comments:
You do not often acknowledge the fact that you currently have a column of gas/air sitting on the top of your head. This column of air exerts a pressure (a force per area) on your head and shoulders. Now this amount of pressure exerted by air is quite smaller compared to the pressure exerted on your hips and knees by your upper body mass, but none the less the column of air above you exerts pressure. This is an interesting demo that i sometime do in class:
Units of gas pressure
The most common gas pressure unit is a Pascal (Pa), but most of you are more familiar with an "atmosphere" (atm). A Pa is equal to 1 Newton of force/1 square meter. The column of air stilling on top of your head right now is exerting ~ 1 atm or 101,325 Pa. Apparently a Pa is a very small unit, so we often use kiloPascals (kPa) and not Pa.
- 1 atm = ~ 101 kPa
Additionally, we use other units for pressure as well that are based on a physical observation. If you had a u-shaped tube and no pressure was exterted on one side and some pressure was exerted on the other side, then you could measure the pressure as a distance a liquid inside the tube has moved.
Another fun set of demos/discussion about air pressure:
Section 5.3: The Gas Laws
Section 5.4: The ideal gas law equation
Section 5.5: Gas Stoichiometry
Section 5.6: Dalton's law of partial pressures
- SKIP