Kinetic Theory Of Gasses (Dr King)

Question 1

State The Ideal Gas Equation

Answer 1

pV=nRT

p=Pa, V=m³, T=K

Question 2

What are the 4 assumptions made by the kinetic gas model?

Answer 2

-Gas particles are in ceaseless random motion, traveling in straight lines between collisions
-Molecules do NOT interact, except when making perfect elastic collisions
-The size of molecules is negligible compared to the distance between collisions
-The energy of the gas is entirely Kinetic Energy

Question 3

State the equation for pressure in the kinetic gas model

Answer 3

pV=⅓nMc²

p=Pa, V=m³, M=Molar Mass, c²=Mean Square Speed

Question 4

Equation for Total Kinetic Energy for an Ideal Gas

Answer 4

KE_Total=³⁄₂nRT

Question 5

What is the Equation for Most Probable Speed?, s*

Answer 5

s*=((2RT)/M)^½

Where M has been converted to kg mol^-1

Question 6

What is the Equation for Mean Speed?, (s)

Answer 6

(s)=((8RT)/(πM))^½

Where M has been converted to kg mol^-1

Question 7

What is the Equation for Mean Square Speed?, c²

Answer 7

c²=(3RT)/M

Question 8

What is the Equation for Root Mean Square Speed?, (s²)^½

Answer 8

(s²)^½=((3RT)/M)^½

Where M has been converted to kg mol^-1

Question 9

What is the area under the maxwell-boltzmann distribution equal to?

Answer 9

unity / 1

Question 10

What is Collision Frequency (Z_A) and what are its units?

Answer 10

The number of collisions made by a molecule per unit time

units = s^-1

Question 11

State the equation to calculate Collision Frequency, Z_A

Answer 11

Z_A=σ√(2)S̄ x (p/(k_BT)

σ=collision cross section,S̄=Mean Speed,k_B=Boltzmann constant

Question 12

What is Mean Free Path (λ) and what are its units?

Answer 12

The average distance travelled by a molecule between collisions

units = m

Question 13

State the equation to calculate Mean Free Path, λ

Answer 13

λ=(RT)/(N_A√(2)σp)

Question 14

What is Rate of Effusion and what are its units?

Answer 14

The rate at which molecules emerge through a small hole in a container

units = (molecules) s^-1

Question 15

How is rate related to the molar mass?

Answer 15

rate ∝ (1/M)^½

Thus Heavier molecules effuse at a Lower Rate than Lighter molecules

Question 16

State Graham’s Law of Effusion

Answer 16

Rate of Effusion = (pAN_A)/(2πMRT)^½

A=Area of the hole

Question 17

The mass loss (Δm) from a container in time interval Δt is?

Answer 17

Δm=M/N_A x Rate of effusion x Δt

Question 18

What is the Van Der Waals Equation

Answer 18

p=(RT)/(V_m-b) - (a/V_m²)

a+b=van der Waals coefficients, V_m=molar volume

SI Units; a=Pa m⁶ mol^-1, b=m³ mol^-1, V_m=m³

Question 19

What does the first part of the van der waals Equation consider?

(RT)/(V_m-b)

Answer 19

It accounts for the finite volume of molecules

Repulsive Interactions

Question 20

What does the second part of the van der waals Equation consider?

-(a/V_m²)

Answer 20

It accounts for the effects of attractive interactions

2 contributions; a reduction in the frequency and force of collisions