Post on 31-Mar-2015
GasStoichiometry
Random Thoughts
1) We live immersed in a gaseous solution.
Random Thoughts
1) We live immersed in a gaseous solution.
2) We live at the bottom of an ocean of air.
Random Thoughts
1) We live immersed in a gaseous solution.
2) We live at the bottom of an ocean of air.
3) Pressure goes from High to Low
Demo: Low Budget Super soaker
Jar with screen
Pressure Defined
1) Pressure = Force / Area
Pressure Defined
1) Pressure = Force / Area
Demo: Nail Board & Cup Holder
Pressure Defined
2) Number of collisions of gas molecules on its surroundings.
Pressure Defined
2) Number of collisions of gas molecules on its surroundings.
Demo: Drink Box
Demo: Shrink Wrapping
Pressure Defined
3) Really the result of the mass of air being pulled to the center of earth.
Gravity
Instrument that measures pressure:
The Barometer - invented by Torricelli; often used mercury as liquid.
--> We get a couple of units from this!
The barometer
High Pressure or Low?
Pair?
Pgas?
The barometer
High Pressure or Low?Gas Inside
OutsideAir pressure
The barometer
High Pressure or Low?Gas Inside
OutsideAir pressure
Low pressure=> outside is losing the push vs the inside.
Pgas = Pair + height
difference
The Barometer High Pressure? Air would be pushing down harder.
Pgas = Pair - height
Lecture Problem-Barometer
Standard Pressure ==> Units
760 mmHg 760 torrs 101300 Pascals 101.3 kPas 1 atm 14.7 lbs/in2
Show dimensional analysis
Gas Law Problems: We have a problem with the gas molecule.
Why is this a problem? 1) They show attraction! Can’t in Gas Law Problems1) They take up space!!! Can’t in Gas Law
Problems
It’s our Physics problem: “Disregard air resistance” How do you do that?
Real Gases
1) They do exist.
2) They can liquefy - condensation of vapor.
3) They don’t follow gas laws.
Ideal Gases
1) They don’t exist.
2) They can’t liquiefy.
3) They follow the gas laws.
So when do gases behave ideally so we can use them in our gas laws?
Where they show no attraction to each other:
What conditions would that be?
So when do gases behave so we can use them in our gas laws? Ideally
Where they show no attraction to each other:
What conditions would that be?
1) Low pressures
2) High temperatures