Chemistry Gas Laws

Observed Properties of Gases

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1. May be compressed

2. Fill containers uniformly

3. Low density (due to spacing of particles)

4. Can be mixed (usually a mixture)

5. Uniform pressure in all directions

Kinetic Molecular Theory of Matter (belief of energy of motion and building block scale)

Lazy Elephants In Soft Valleys

1. Molecules move in straight lines

2. Molecules collide with each other without losing energy (elastic collisions)

3. Molecules are independent (no attraction forces between)

4. Molecules are spread out

5. Volume of molecules are small in comparison to space occupied

Relate to properties: Molecules move in straight lines

Fill containers uniformly

Uniform pressure in all directions

Relate to properties: Elastic collisions

Fill containers uniformly

Relate to properties: Molecules are independent

Can be mixed

Relate to properties: Molecules are spaced out

May be compressed

Relate to properties: Volumes of molecules is small compared to space occupied

May be compressed

Low density

Ideal Gas

Follows KMT + Predictions

Theoretical

Real Gas

Real gases deviate from predictions greatly

Everything we use

Low temps or High pressure

Pressure

Pressure is the amount of force applied over an area.

P= F/A

Experiments with gas usually involve controlling or measuring its…

1. Quantity

2. Volume

3. Pressure

4. Temperature

Quantity is measured in..

n=moles (often held constant)

Volume is measured in…

L, mL, m³,dm³ L=dm³

Pressure is measured in…

kPa, mmHg,torr, atm

Use barometer to measure

STP

• Temperature: 0 °C (273.15 K)

• Pressure: 1 atmosphere (1 atm) or 101.3 kPa

Standard Molar Volume of Gas

At STP one mole of ANY gas is 22.4L

Ideal Gas Law

PV=nRT

What is temperature a measure of?

Average kinetic energy

Absolute Zero

Theoretically when molecules stop moving

Boyle Law

• Constant temp and quantity

• Pressure and volume are inversely related

Gas-Lussac Law

• Pressure and temperature are proportionally related

• Constant volume and quantity

Charles Law

• Constant pressure and quantity

• Volume and temperature are proportionally related.

How to add molar mass into the combined gas law?

_{n=mass/molar mass}

_PV=m/mmRT

How to solve for density

Gas= PM/RT

When is ideal gas law used?

1. Solve for single variable

2. Gas density (g/L)

3. Solve for molar volume (L/mol)

Partial Pressures

The total pressure of a mixture of gasses is made up from the sum of partial pressures of the component gases.

Diffusion

The gradual mixing of two or more gases due to their spontaneous, random motion.

Effusion

The molecules of a gas confined in a container randomly pass through a tiny opening in the container.

Rate of effusion, which effuses faster?

Lighter gases effuse faster

Rate of effusion formula