Concentration Review
1) If I make a solution by adding 83 grams of sodium hydroxide to 750 mL of water…
a) What is the molality of sodium hydroxide in this solution? (density of water is 1g/ml)
b) What is the percent by mass of sodium hydroxide in this solution?
c) What is the mole fraction of sodium hydroxide in this solution?
2) If I make a solution by adding water to 35 mL of methanol (CH3OH) until the final volume of the
solution is 275 mL…
a) What is the molarity of methanol in this solution? (The density of methanol is 0.792 g/mL)
b) What is the percent by volume of methanol in this solution?
3) How many moles of ethyl alcohol, C2H5OH, are present in 65 mL of a 1.5 M solution?
4) How many liters of a 6.0 M solution of acetic acid CH3COOH, contain 0.0030 moles of acetic acid?
5) You want 85 g of KOH. How much of a 3.0 m solution of KOH will provide it?
6) If you dissolve 0.70 moles of HCl in enough water to prepare 250 mL of solution, what is the molarity
of the solution you have prepared?
7) A solution is prepared by adding 2.0 L of 6.0 M HCl to 500 mL of a 9.0 M HCl solution. What is the
molarity of the new solution? (Remember, the volumes are additive)
8) Convert the following Molarities to Normalities. a. 2.5 M HCl = N b. 1.4 M H2SO4 = N c. 1.0 M NaOH =
N d. 0.5 M Ca(OH)2 = N
9) A commonly purchased disinfectant is a 3.0% (by mass) solution of hydrogen peroxide (H2O2) in
water. Assuming the density of the solution is 1.0 g/cm3 , calculate the molarity and molality of H2O2.
10) A solution is made by dissolving 25 g of NaCl in enough water to make 1.0 L of solution. Assume the
density of the solution is 1.0 g/cm3 . Calculate the molarity and molality of the solution.
11) What is the mass percent of a solution that contains 152 g of KNO3 in 7.86 L of water?
12) A solution has been prepared to be 9.00 % (by mass) glucose. For every 100.0 grams of solution
present there are _________________ grams of glucose.
13) How many grams of KBr are contained in 250. grams of a 6.25 % KBr solution?
14) What is the concentration of each type of ion and total concentration of ions in a 0.375 M
Ammonium phosphate solution?
13. How many moles of chloride ions are in 1.50 L of 4.15 M zinc chloride?
Colligative Properties Review
1) If I add 45 grams of sodium chloride to 500 grams of water, what will the melting and boiling points
be of the resulting solution? Kb(H2O) = 0.52 °C/m and Kf(H2O) = 1.86°C/m.
2) What is the vapor pressure of the solution in problem #1 at 25°C? The vapor pressure of pure water
at 25°C is 3.17 kPa.
3) Which solution will have a higher boiling point: A solution containing 105 grams of sucrose (C12H22O11)
in 500 grams of water or a solution containing 35 grams of sodium chloride in 500 grams of water?
Explain
4) How many grams of ethylene glycol, C2H4(OH)2, must be dissolved in 200 grams of water to lower the
freezing point to -29.75oC?
If the density of ethylene glycol is 1.12 g/ml, how many milliliters of ethylene glycol are required?
5) What is the composition (mole fractions) of a methanol (CH3OH)- propoanol (CH3CH2CH2OH) solution
that has a vapor pressure of 174 torr at 40C? At 40C, the vapor pressures of pure methanol and pure
propanol are 303 and 44.6 torr, respectively.