# Unit 11

## 27 terms · Gas Laws. Lessons 41 & 42.

### What is kinetic molecular theory?

the theory that explains the behavior of gases at the molecular level

### What is an ideal gas?

a model that effectively describes the behavior of real gases at conditions close to STP (STANDARD TEMPERATURE AND PRESSURE);
OR
a gas for which the product of the PRESSURE and VOLUME is proportional to the ABSOLUTE TEMPERATURE

### What are the 4 parts to the kinetic molecular theory?

1. Ideal gas particles are very small: their volume is essentially zero when compared with the total volume of the gas.
2. They are in constant rapid motion
3. there are NO attractive and repulsive forces; collisions are completely elastic
4. the average kinetic energy is DIRECTLY proportional to the absolute temperature, measured in KELVIN

### What does kinetic molecular mean?

movement of molecules.

### What assumptions do we make for ideal gas? Is it realistic?

IT IS NOT REALISTIC.
1. no particles can take up zero volume. we assume this.
2. the attractive/repulsive forces are very small, so we disregard them. they begin to matter when the particles come very close together: then they begin to condense.
3. there is no such thing as totally elastic collision: energy is always transferred. However, particles do conserve ALMOST all of their energy.

### What are the four variables that describe a gas?

1. Temperature.
2. Volume.
3. Pressure.
4. Number of molecules.

### The temperature of a gas determines what?

the average kinetic energy of the particles

### Do all gas particles travel at the same speed?

false. they travel at different speeds.

### *****TEMPERATURE FOR GAS MUST BE EXPRESSED IN?*****

Kelvin. Always.
If given Celsius, add 273 to get Kelvin.
Also, there is no degree mark for Kelvin. Just "K".

### 0 in Kelvin represents what?

no molecular motion. absolute zero.

### How do you derive the volume of a gas?

Linear measurements.

### What is the formula for volume?

length x width x height

1000 cm³ = 1 dm³

### What is the formula for pressure?

force divided by area. Ex: The pressure of a gas is the force of its particles exerted over an area.

### Define pressure.

the force exerted per unit area.

### Adding particles, or reducing the space for the particles, results in?

greater pressure; an increase in collisions of the particles.

pascal.

1 N/m²

### What is the conversion from mmHg - torr - kPa for 1 atm?

750 mmHg -1 atm.
750 torr - 1 atm.
101.325 kPa - 1 atm.

### Are mmHg and torr equal?

yes. they are exactly equal, and they mean the same exact thing.

### How do you express the number of molecules?

in moles. If you are given grams, convert.

### Gases with equal volumes have ______ numbers of particles.

equal

Equal volumes of different gases under the same conditions have the same number of molecules.

yes!

### What is molar volume?

the volume of one mole of a substance at STP.

### ****WHAT IS THE MOLAR VOLUME FOR ANY GAS??!??!***

22.4 L <---- this is very very very important

### What is STP (Standard Temperature and Pressure)?

Standard conditions for a gas of:
- 0 degrees Celsius (273 Kelvin)
- 1.0000 atmospheres.

Other examples of STP conditions are:
1. 273 K and 101.325 kPa
2. 273 K and 760.0 mmHg
3. 273 K and 760.0 torr

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