Chapter 13.1-13.4 problems
November 28, 2011
• What IMF(s) is/are present when…
a) KCl is dissolved in H2O
b) carnauba wax dissolves in castor oil
c) Methanol (CH3OH) vs CCl4
• Arrange the following in increasing solubility:
A
B
C
• Which solvent will yield the highest
concentration of NaCl?
a)
b)
• Which will have the highest concentration in
diethyl ether (
)?
A. HCl (g)
B. NaCl (s)
C. H2O
Why will washing your face with soap make your
face “dryer”? (clue: remember your lipbalm
experiment)
• When NH4Cl dissolves in water, the solution
becomes colder…
A) Is ΔHsol’n >, < or = to 0?
B) Is ΔHlattice >, <, or = to ΔHhydration ?
C) Is the dissolution mostly due to ΔH or ΔS of
mixing?
• CHARGE DENSITY affects ΔHhydration. Which one
will have a higher (more negative) ΔHhydration ?
A) Na+ , Rb+
B) Br-, IC) Ca2+, Na+
• Which best depicts the dissolution of NaI
(exothermic)?
• Which one best describes the enthalpy
diagram of dissolving KBr in hexane?
• Henry’s Law constant (kH) of O2 in water at
20oC is 1.28 x 10-3 mol/L-atm.
a) How many grams will dissolve in 2.50 L H2O
that is in contact with pure O2 at 1.00 atm?
b) How many grams will dissolve in 2.50 L H2O
that is in contact with pure O2 at 0.209 atm?
• Express the concentration of concentrated HCl
(12M)? Assume density of solution to be that
of water: 1.00g/mL
a) Molality
b) %w/w
c) %v/v
d) Mol fraction
• Argon makes up 0.93% by volume of air.
Calculate its solubility (in molars) in water at
20oC and 1.0 atm. (kH of Ar is 1.5x10-3 mol/Latm)
• How many grams of NaCl more is needed to
prepare a 100.0 mL of 0.1000 molal from
100.0 mL of 0.1000 molar NaCl solution?
• How many grams of water must be
evaporated from a liter of solution to make a
20%(w/w) MgBr2 to make a 0.0010 molar
solution?
• You are to prepare 10.0mL 0.0430 M ethanol
solution from a stock solution of 20% v/v
ethanol. The density of ethanol is 0.789g/mL.
How many mL of the stock solution should
you use?
• Air is 21%(w/w) oxygen. If the molar mass of
air is 28.4 grams/mol, calculate the mol ratio
of oxygen in the air.