Final Review

Question 1

Raoult’s Law

Answer 1

Pa = XaPa°
Pa = pressure of solution
Xa = mole fraction of solvent
Pa° = pressure of solvent

Anything that’s not a liquid doesn’t have a vapor pressure and is nonvolatile!

Question 2

Dalton’s Law

Answer 2

Pa = XaPtot
Pa: partial pressure
Xa: mole fraction of gas in vapor above solution
Ptot: total pressure

Question 3

Colligative property formula for change in temperature

Answer 3

∆T = ikm
∆T: temperature change of the solvent
i: number of particles of solute
k: constant for SOLVENT
m: moles of solute per kg solvent

Question 4

Colligative property formula for osmotic pressure

Answer 4

π = iMRT
π: osmotic pressure
M: molarity
R: ideal gas constant (8.3145 J/molK)
T: temperature (K)

Question 5

Henry’s Law

Answer 5

C = kPgas
C = C1/P1 = C2/P2
C: solubility/concentration
k: Henry’s Law constant
Pgas: the pressure of the gas

k is sometimes shown as 1/k, so just take the reciprocal (1/that number) to find k

Question 6

Clausius-Clapeyron equation

Answer 6

ln(P2/P1) = ∆H/R(1/T1-1/T2)
T1/T2: temperature (K)

Question 7

How to determine volatility of a molecule

Answer 7

Least polar and least molecular weight = most volatile
Most polar and most molecular weight = least volatile

Question 8

Forming solutions, what is the sign of ∆H for ∆H1, ∆H2, ∆H3? Also determine whether ∆Hsoln is large or small.

Answer 8

Positive (∆H1), positive (∆H2), negative (∆H3)

∆Hsoln is small if the previous three were large but small otherwise

Outcome is solution forms if ∆Hsoln is small and it doesn’t if ∆Hsoln is large

Polar means large value, nonpolar means small value

Question 9

When is the solubility of gas the highest?

Answer 9

Under low temperature and high pressure

Question 10

What molecules tend to be the most viscous?

Answer 10

Large molecules

Question 11

Molality

Answer 11

Moles solute/kg solvent

Question 12

Molarity

Answer 12

Moles solute/L solution