Module 15 Flashcards
Kinetic Energy
Energy in form of motion
Kinetic Theory of Energy
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
Charle’s Law
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
Another kinetic energy formula w/ v and m
E_k = (1/2) *m * v**2
m = mass
v = speed
ve
E_k (mass +vol) =E_k (Temp)
(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
Boyle’s Law
P_initial*Vol_initial = P_final *Vol_final
Normal atmospheric pressure
1 atm
van der Waals
(p+a(n^2/V^2))(V-nb)=nRT
van der Waal - a and b
relationships w/ vaporization and particle diameter
higher heat of vaporization = stronger particle attraction
stronger particle attraction
= larger a
bigger particle diameter = larger particles
larger particles = larger b
Ideal gas law
p = (nRT)/V
Calculating mole fraction of gas mixture
- Find moles of each gas
- Add for total
- Divide each moles of gas by total to get mole fraction of each
Relative Effusion Rates to Unknown Molar Mass
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
Graham’s Law
r1 / r2 = sqrt(A2 / A1)
r1, r2 = rates of effusion of two gases
A1, A2 = gas’ molar mass
Avogadro’s Law
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)
Ideal Equation of State
= Ideal Gas Law
Partial Pressure
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
Density
m/v = p (density)
PV = (mass/Nolar_mass)RT
p = (P/RT) * Molar_mass
Charles’s Law + Boyle’s Law = Combined Gas Law
(P_i * V_i ) / T_i = (P_f * V_f) / T_f
Reasons for nonideality of a gas
- 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.
Determining if a nonideal gas
- Find ideal P using Ideal Gas Law
P = nRT/V - 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
Calculating gas mass collected over water
- Know that H2O is also inclu. in that gas
- P_gas + P_h2o = 1 atm
- Find water vapor pressure at specified temp
- Plug that into above eqn to get P_gas
- Then use P_gas in Ideal Gas Law Eqn to find moles
- Coonvert moles to mass
units of a
atm*L^2 / mol^2
OR
whatever units left over to get a
units of b
L/mol
