Chapter 4 - Ideal Gas Laws

Question 1

what are phases and phase transitions?

Answer 1

there are just three states of matter

1. solid
2. liquid
3. gas

Question 2

what does fusion mean?

Answer 2

melting

Question 3

what does vaporization mean?

Answer 3

aka boiling

Question 4

what does crystallization mean?

Answer 4

freezing

Question 5

what does condensation mean?

Answer 5

conversion of vapour gas into liquid gas

Question 6

what is the kinetic molecular theory?

Answer 6

it describes the behaviour of gases

1. Gas molecules are extremely small (mass but no volume)
2. Gas is in constant, random, straight-line motion, collisions are elastic
3. Molecules of gas experience no intermolecular forces
4. Gas molecules span a distribution of speeds, and average kinetic energy is directly proportional to temperature
5. Ideal gases satisfy all these criteria under most ordinary conditions

Question 7

do ideal gases experience phase changes?

Answer 7

no phase changes with ideal gases because by definition there are no intermolecular forces

Question 8

what is barometric pressure?

Answer 8

• used to measure atmospheric pressure
• uses mercury (high density, p=13.5951g/ml at 0degrees)
• the atmosphere exerts the same pressure on the surface of the mercury both inside and outside the tube, and the liquid levels are equal

Question 9

comparing liquid pressures?

Answer 9

use this formula to compare liquid pressures 
P = hgd
h - height of column
g - gravity (9.81)
d - density

Question 10

what are manometers?

Answer 10

pressure gauge for determining the pressure of a gas

1. Patm > Pgas; Pgas = Patm - ΔH
2. Patm

Question 11

What is the ideal gas law?

Answer 11

relationship between volume, temperature and pressure of and ideal gas

PV = nRT

Question 12

what is R when pressure units are in bars?

Answer 12

R = 0.083145

Question 13

what is R when pressure units are in atmospheres?

Answer 13

R = 0.08206

Question 14

What is R when pressure units are in Joules?

Answer 14

R = 8.3145

Question 15

what is the general gas equation?

Answer 15

sometimes a gas is described under two different conditions, initial (1) and final (2)
P1V1/n1T1 = P2V2/n2T2

Question 16

what is Charles law?

Answer 16

Charles law states that volume and temperature are directly proportional at constant pressure

V1/T1 = V2/T2

Question 17

What is Boyle’s Law?

Answer 17

Boyle’s law states that pressure is inversely proportional to volume at constant pressure

P1V1 = P2V2

Question 18

What is Amonton’s law?

Answer 18

Amonton’s law states that pressure is directly proportional to temperature at a constant volume

P1/T1 = P2/T2

Question 19

what is Avagadro’s Law?

Answer 19

Avagadro’s law states that the volume of gas is directly proportional to the amount of gas at a fixed temperature and pressure

V1/n1 = V2/n2

At STP 1mol of gas equals 22.7L of gas

Question 20

what is the Molar mass determination from the ideal gas law?

Answer 20

M = mRT/PV

Question 21

what is the density determination from the ideal gas law?

Answer 21

d = MP/RT

Question 22

The density of a gas is…?

Answer 22

The density of a gas is proportional to its molar mass: the lower the molar mass, the greater its lifting power

Question 23

what is a mixture of gases?

Answer 23

• Partial pressure is the pressure that molecules of each gas exert

Question 24

What is Dalton’s Law of Partial Pressure?

Answer 24

it states that the total pressure of mixture of the gases is the sum of the partial pressures of each of the individual gases that make up the mixture

Ptotal = Pa + Pb +....
Pa = Xa * Ptotal

Question 25

What is mole fraction?

Answer 25

``` Xa = n(a)/n(total) = Pa/Ptotal = Va/Vtotal n(total) = n(a) + n(b) +... Ptotal = Pa + Pb +.... Vtotal = Va + Vb +.... ```

Question 26

what is Root Mean Square Velocity (Urms)?

Answer 26

- Close to the average speed of the particle - Inversely proportional to the molecular mass of the gas - molecular mass in kilograms (kg) - R = 8.3145 J/mol*K - M = molar mass Urms = ✓3RT/M

Question 27

What is the Ideal vs Non-ideal gas?

Answer 27

Van der Waaals Equation: RT = (P + a/Vm^2)(Vm - b); Vm = molar volume - Real gas must include the volume of the gas particles - Real gas has intermolecular forces unlike ideal gases

Question 28

When do real gases behave Ideally?

Answer 28

Gases behave ideally at.. 1. High temperatures 2. Low Pressures

Question 29

In Van der Waals Equation what do (a) and (b) do?

Answer 29

(a) - larger (a) means stronger attraction and lower pressure (b) - larger (b) means more excluded volumes and higher pressure

Question 30

Directly proportional means?

Answer 30

If variables are on the opposite side of each other in an equation or they're divided by each other, they are directly proportional to each other (Eg. if one increase the other increase)

Question 31

Inversely proportional means?

Answer 31

If variables are on the same sides of the equation as each other, or if they are multiplied by each other they are inversely proportional (Eg. If one increase the other decrease)