Module 15

Question 1

Kinetic Energy

Answer 1

Energy in form of motion

Question 2

Kinetic Theory of Energy

Answer 2

Average kinetic energy (E_k) of atoms/molecules of gas is proportional to absolute temperature (T) of gas.

E_k = (3/2)* k_B * T

k_B is Boltzmann constant
= 1.38065*10^-23 J·K^-1

Question 3

Charle’s Law

Answer 3

Volume of gas directly proportional to absolute temperature (at constant pressure)

T_final / T_initial = special_number

Charle’s Law:
Volume_final = special_number * Volume_initial

Question 4

Another kinetic energy formula w/ v and m

Answer 4

E_k = (1/2) *m * v**2
m = mass
v = speed

Question 5

ve

Question 6

E_k (mass +vol) =E_k (Temp)

Answer 6

(1/2)mv2 = (3/2)k_BT

v = sqrt( (3k_BT) / m)

Note: for m, convert it to kg, so it can cancel out boltzmann constant’s kg
The JK^-1 in Boltzmann’s can convert into kgm^2s^-2K^-1

Question 7

Boyle’s Law

Answer 7

P_initial*Vol_initial = P_final *Vol_final

Question 8

Normal atmospheric pressure

Answer 8

1 atm

Question 9

van der Waals

Answer 9

(p+a(n^2/V^2))(V-nb)=nRT

Question 10

van der Waal - a and b
relationships w/ vaporization and particle diameter

Answer 10

higher heat of vaporization = stronger particle attraction
stronger particle attraction
= larger a
bigger particle diameter = larger particles
larger particles = larger b

Question 11

Ideal gas law

Answer 11

p = (nRT)/V

Question 12

Calculating mole fraction of gas mixture

Answer 12

1. Find moles of each gas
2. Add for total
3. Divide each moles of gas by total to get mole fraction of each

Question 13

Relative Effusion Rates to Unknown Molar Mass

Answer 13

see Graham’s Law
substitute
A2 in Graham’s Law w/ molar mass of unknown
A1 for molar mass of given gas
r1/r2 for given effusion rate

Question 14

Graham’s Law

Answer 14

r1 / r2 = sqrt(A2 / A1)
r1, r2 = rates of effusion of two gases
A1, A2 = gas’ molar mass

Question 15

Avogadro’s Law

Answer 15

equal volumes of gases at same temp and pressure contain equal moles
Ex) 1L of F2 at 25C = 1L pf O2 at 25C

**also implies ratio of volumes of gases = ratio of moles

volume of O2 / volume of F2 = 1 mol O2 / 2 mol F2 (mole ratio of a random equation)

Question 16

Ideal Equation of State

Answer 16

= Ideal Gas Law

Question 17

Partial Pressure

Answer 17

Partial Pressure = Total Pressure * mole fraction of gas

Total Pressure = 1Pi + 2Pi…

Ideal Gas Law Ver.
Partial Pressure =
(n_i * R * T) / V

n_i = mole fraction
V = total volume

Question 18

Density

Answer 18

m/v = p (density)

PV = (mass/Nolar_mass)RT
p = (P/RT) * Molar_mass

Question 19

Charles’s Law + Boyle’s Law = Combined Gas Law

Answer 19

(P_i * V_i ) / T_i = (P_f * V_f) / T_f

Question 20

Reasons for nonideality of a gas

Answer 20

• There are attractions btwn gas particles
  Ideal gas have none. However, IRL gas have attractions , which make gas particles stick to each other, thus, decreasing pressure below an ideal gas’s
• The particles don’t have volume of zero
  Ideal gas particles have zero volume. IRL gas’ don’t, so particles bounce off each other hoarder and more frequently, thus increasing pressure above an ideal gas’s.

Question 21

Determining if a nonideal gas

Answer 21

1. Find ideal P using Ideal Gas Law
   P = nRT/V
2. Compare to ideal P to actual P within # of sig figs it has to ideal pressure

If actual P greater than ideal P -> nonideal, particles have above zero volume

If actual P below ideal P -> nonideal, attractions btwn particles

If actual P =(ish) ideal P -> ideal

Question 22

Calculating gas mass collected over water

Answer 22

1. Know that H2O is also inclu. in that gas
2. P_gas + P_h2o = 1 atm
3. Find water vapor pressure at specified temp
4. Plug that into above eqn to get P_gas
5. Then use P_gas in Ideal Gas Law Eqn to find moles
6. Coonvert moles to mass

Question 23

units of a

Answer 23

atm*L^2 / mol^2

OR

whatever units left over to get a

Question 24

units of b

Answer 24

L/mol