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