# Unit 7: Gases

## 15 terms

### Kinetic Molecular Theory (KMT)

a model that explains the behavior of gases;
Four assumptions:
1. Gas particles are in continuous, random, straight-line motion
2. When gas particles collide, energy is transferred from one particle to another (elastic collisions)
3. Gas particles have no attraction to each other (no IMF)
4. Individual gas particles have no volume (negligible)

### ideal gas

an imaginary gas that perfectly fits all the assumptions of the kinetic-molecular theory

### real gas

a gas that actually exists; deviate (stray) from ideal gas behavior

Under the same conditions of temperature and pressure, EQUAL VOLUMES of different gases contain EQUAL NUMBERS OF GAS PARTICLES.

### Combined gas law

equation relating the pressure, temperature, and volume of a gas
Table T
P1V1/T1 = P2V2/T2

### Boyle's law (P1V1 = P2V2)

The relationship between the pressure and volume of a gas; when volume increases, pressure decreases (at constant temperature)

### Charles' Law (V1/T1 = V2/T2)

The relationship between the volume and temperature of a gas; when the temperature of a gas increases, the volume of the gas increases (at constant pressure)

### Gay-Lussac's law (P1/T1 = P2/T2)

The relationship between the pressure and temperature of a gas; when temperature increases, the pressure of the gas increases (at constant volume)

### STP

Standard Temperature and Pressure
Table A
273 K (ALWAYS USE KELVIN FOR GASES!)
1 atm or 101.3 kPa

### pressure

the force of the gas particle collisions with one another and with the sides of the container

### movable piston

a part of a container that allows the volume of the container to increase or decrease

### rigid container

a container in which the volume is constant/does not change

### temperature

a measure of the average kinetic energy of the gas particles
Units: degrees Celsius or Kelvins
*always use Kelvins for gases!!!!

### volume

the space taken up by a gas
Units: L or mL or cm^3
(1 mL = 1 cm^3)

### entropy

disorder or randomness
*highest in gases