gases. what are gases? why are gases so hard to study? gases are harder to study than other states...

GASES

WHAT ARE GASES?

WHY ARE GASES SO HARD TO STUDY?

Gases are harder to study than other states of matter.

They fly around, they are hard to see, they try to escape.

Scientists made some assumptions.

Let’s say we want to study dogs as a group.What assumptions can we make

KINETIC MOLECULAR THEORY OF GASES

What assumptions can we make about gases?

http://www.youtube.com/watch?v=93niv-

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KINETIC MOLECULAR THEORY

1)Gases consist of really really small particles that are really really far apart.

2) Gases are always moving (in a bumpy way)

3)Don’t experience intermolecular forces. (story of the kid you don’t like)

4)The kinetic energies of gas molecules are directly proportional to their temperature in Kelvin.

5)Gas molecules undergo elastic collisions.

HOW FAST DO GAS MOLECULES MOVE?

Kinetic energy is proportional to temperature only. What does this mean?

So light objects move faster than heavy objects

PRESSURE

Pressure- amount of force exerted by the particles

What things can affect the Pressure of a container

PROUD TO BE A PV=NRT

Any math anybody asks you to do about gases can be done with this equation. You can use it all or just the parts that are changing.

PV = nRT

http://www.youtube.com/watch?v=JsoE4F2Pb20

http://www.youtube.com/watch?v=Zz95_VvTxZM

WAYS TO TALK ABOUT PRESSURE?

1 atm = 760 mm Hg = 14.7 psi= 101,325 pascals = 101.3 kPa

THINGS THAT EFFECT PRESSUREVolumeTemperatureAmount (moles)

THINGS ABOUT GASES WE LEARN FROM OUR LABS.

ONE WE WON’T DO IN OUR LABBECAUSE WE AREN’T IDIOTS

Video of someone throwing a spray paint can in the fire.

A LITTLE MATH

If I compress 1,500 L of nitrogen at an initial pressure of 1 atm until the pressure reraches 450 atm. What will the new volume of gas be?

A LITTLE HARDER AND A LITTLE LESS HELPI’ve got a balloon. It has 30.0 L of helium gas at 103kPa. I let

it go in the sky and it floats up to where the pressure is only 25.0 kPa. What is my new volume?

We have a big old can on the stove. It holds 5.00 L I heat it on the stove to 250 degrees C. If I close the lid and let it cool down to 25 degrees C what will be the final volume of the can?

I blow up a balloon at 24 degrees C. It has a volume of 4.00 L I then take it to a sauna and turn the heat up to 58 degrees C. What will the new volume of the balloon be?

What else can you do with a PV=nRT?

Solve for any one of the five as long as they give you the other four.

I’ve got a tennis ball filled with Nitrogen gas. It’s 34 degrees C today. The volume of the tennis ball is .148 L and the pressure inside the tennis ball is 212 kPa.

How many moles of Nitrogen are inside my tennis ball?

Could I figure out how many grams of N2 are in my tennis ball? How?

LAST ONE

A deep underground cave contains 2.24 x 106 L of methane gas at a pressure of

1.5 x 103 kPa and a temperature of 315 K. How many kilograms of CH4 are in the cave?