Calculations
For a system at 1 atm, if V is halved and T is doubled, what is the new pressure?
4 atm
Rank the following by least ideal to most ideal in the terms of Van der Waals coefficient a:
N2 HCl H2 HF NH3
What is the dominant IMF in :
1) KCl
2)XeF4
3)C2H5OH
4)NO2
1) KCl= ionic
2)XeF4= dispersion
3)C2H5OH= h-bonding
4)NO2= dipole-dipole
What are the 5 statements of KMT
• All gases are simple hard spheres
• All gases are infinitely small compares to V(system)
• Gases have elastic collisions so no energy change • KE 𝛼 T, as T increases, KE increases
• KE 𝛼 𝑚𝜈 2 so mass is inverse square with velocity. Large gases move slow
Boyle's Law Equation?
What kind of relationship is there between the variables?
inverse relationship of pressure and volume
What volume will 60 L of He at 40 *C and 1500 torr occupy at STP?
103.3 L
Rank the following by melting point
HBr MgCl2 CO2 Al2O3 CHF3 NH3
CO2< HBr < CHF3< NH3< MgCl2 < Al2O3
1) dispersive
2) dipole-dipole
3)h-bond
4)ionic
1) nonpolar molecules
2) polar molecules
3) in molecules with OH, HF, or NH bonds
4) in salts/ anion+cation compounds
What are the ideal conditions for gases?
Low Pressure
High Volume
Low amount of moles
High Temperature
Small and Nonpolar
What is Graham's Law?
What is the relationship between size and speed?
m1v1^2= m2v2^2
speed and size are inversely related
In a 150 L flask at 400 K, 56 grams of nitrogen and 56 grams of hydrogen react completely according to the balanced equation below. What is the final pressure?
N2(g) + 3 H2(g) ⇆ 2 NH3(ℓ)
5.4 atm
rank in terms of increasing viscosity and evaporation rate
C5H12 H2O C6H6
Viscosity: C5H12< C6H6< H2O
Evap rate: H2O< C6H6< C5H12
Assign IMFs to the following molecules
CH3Cl BaO H2 NH3 N2 CHCl3 KBr
CH3Cl dipole-dipole BaO ionic
H2 dispersion NH3 hydrogen bonding
N2 dispersion CHCl3 dipole-dipole
KBr ionic
Calculate the ratio of the rate of diffusion of N2 to that of Si2 (same temperatures).
√2 : 1
What is the combined gas law equation?
1atm= ? torr
Convert 30 C to K.
(P1V1)/T1 = (P2V2)/T2
1 atm= 760 torr
273 + 30 = 303 K
A 22.4 L vessel contains 0.08 mol H2 gas,
0.02 mol N2 gas, and 0.1 mol NH3 gas. The
total pressure is 700 torr. What is the partial
pressure of the H2 gas?
280 torr
Rank the following by increasing order of ideality in the terms of Van der Waals coefficient b:
Rn H2 CO2 He SF6 N2 CH4
H2< He< CH4< N2 < CO2< SF6< Rn
What are the 7 liquid propeties that are directly related to IMF?
What are the 2 liquid properties that are inversely related to IMF?
Boiling point, melting point, capillary action, gas nonideality, viscosity, surface tension, and heat of vaporization
evaporation rate and vapor pressure
a corrects for?
What has large a?
b corrects for?
What has large b?
a corrects for stickness (polarity).
Large polar gases have large a.
b corrects for size.
Large molecules have large b.
What is Charles' Law?
What is the relationship between the variables?
direct relationship between volume and temperature
Which of the following have the highest density:
1 mole of CH4 at .1 atm and 273K
2 moles of O2 at 1 atm and 300K
3 moles of H2 at 3 atm and 290 K
Answer: O2
CH4: ρ = PMW / RT
= (.1 atm)(16g/mol) / (0.082 Latm/Kmol)(273K) = 0.07147 g/L
O2 ρ = PMW / RT
= (1 atm)(32g/mol) / (0.082 Latm/Kmol)(300K) = 1.3 g/L
H2 ρ = PMW / RT
= (3 atm)(2g/mol) / (0.082 Latm/Kmol)(290K) = 0.2523 g/L
I have 128g of CH3OH and 320 g of O2.
2CH3OH + 3O2 ---->2CO2 +4H2O
CH3OH= 32g O2= 32g
What is the product volume?
What is the total system volume?
What is the change in volume? decrease or increase or stays the same?
product volume= 268.8
total system volume= 358.4
change in volume= increased by 44 l
How many buckets are needed for the following
CH4 K2S H2O COOH CO2 N2
3
520 g of an unknown gas occupies a volume of 40 L at 6 atm and 180 K. What is the identity of the gas?
N2 Ne CO2 O2 Ar
O2
Dalton's Law?
Avagadro's Law?
Guy Lussac's Law?
Dalton's Law:
Ptot = P1+P2+P3....
(additive nature of gas partial pressures)
Avogadro's Law:
(equal volumes of gas at constant temperatures (T) and pressure (P)
have the same number of moles (n))
Gay Lussac's Law:
(at a constant pressure (P) and temperature (T), gases combine in
simple proportion by volume)