Exam 2

Question 1

MOLALITY

Answer 1

= mol/kg

Question 2

when asked about aqueous solution of %[]X by mass, and a density of y; when asked molarity of X, what to do?

Answer 2

1. Assume 1 L solution, b/c molarity. 1L -> 1000 mL = 1000 cm^3.
2. Use density times 1000 mL (or whatever is in denominator) to find grams in solution.
3. Grams times %[]X = grams of X. multiply by molar mass, to get mol/L.

Question 3

more dissociated ions -> [ ] osmotic pressure?

Answer 3

more dissociated ions -> higher osmotic pressure, b/c higher I and also higher M.

Question 4

when to use the different vapor pressure equations?

Answer 4

Use the Ps = XsP0: when finding vapor pressure of solvent above a solution.

Use the deltaP = P0Xs: when finding CHANGE in vapor pressure due to PRESENCE of NON-VOLATILE SOLUTE.

Use the Pn=XnPt: when finding the PARTIAL PRESSURE in a GASEOUS MIXTURE.