Gases

Question 1

What are the Properties of Gases?

Answer 1

• Gases are compressible. (Pressure up then Volume down )
• Gases expand when temperature increases (Temperature up, then Volume up )
• Gases have low viscosity ( Flows Easily )
• Gases have lower densities.
• Gases mix completely and evenly.

Question 2

Ideal Gases

Answer 2

• Molecules size are negligible
• No intermolecular forces
• Collisions are elastic (no net loss)

Question 3

Real Gases

Answer 3

• Molecule size is significant in high pressures
• Intermolecular forces = condensation in low temps
• Inelastic collisions

Question 4

kPa -> atm
atm -> mmHg
torr -> mmHg

Answer 4

1 atm = 101.325kPa
760 mmHg = 1 atm
1 torr = 1 mmHg

Question 5

Define temperature

Answer 5

• Avg kinetic energy of a particle
• The more kinetic energy particle has, the higher the temperature

Question 6

Absolute zero in C and K

Answer 6

-275.15 C
0 K

Question 7

Celsius to Kelvin
Kelvin to Celsius

Answer 7

C -> K, +273.15
K -> C, -273.15

Question 8

Define STP and SATP

Answer 8

• STP: 273.15K (0C) and 100kPa
• SATP: 298.15K (25C) and 100kPa

Question 9

Boyle’s Law

Answer 9

• Pressure increase, Volume decrease
• P1V1 = P2V2
• Temp and moles same

Question 10

Charles’s Law

Answer 10

• Temperature increase, Volume increases
• Temperatures must be KELVINS
• V1/T1 = V2/T2
• Pressure and moles same

Question 11

Gay-Lussac’s Law

Answer 11

• Pressure increase, temperature increases

Question 12

What if number of moles change?

Answer 12

• Calculate the new volume using n(Vm)
• n = number of moles
• Vm = Molar volume

Question 13

SATP and STP Vm

Answer 13

• SATP Vm = 24.8 L/mol
• STP Vm = 22.7 L/mol

Question 14

What is the combined gas law?

Answer 14

• Pressure and Volume is proportional to the temperature in Kelvin.
• moles same