Solutions - Concentrations/HW
Name: __________________________
1) Calculate the mass percent and mol fraction of 3.78 g of NaBr in 60.1 g of solution. (ans: 6.29%;
0.012)
2) Calculate the amount of water in grams that must be added to 5.00 g urea ((NH2)2CO) to prepare a
16.2 % by mass solution. (ans: 25.86g)
3) Express the following aqueous concentrations in the unit indicated:
a) 5 g trichloroethylene/L in ppb trichloroethylene. (ans: 5ppb)
b) 0.0025 g KI/L water in ppm of KI (ans: 2.5ppm)
4) Calculate the following for a 1.22 M sugar solution (density 1.12 g/mL) (Sugar is C12H22O12, MW
= 342.3 g/mol) a) the molality; and b) the mass percent of sugar. (ans: 1.73m; 37.3%)
Dr. Gupta/Solutions/HW/Page 1 of 2
5) Sodium fluoride has a solubility of 3.84 g in 85 g of water. Express that concentration in terms of
a) mass percent; b) mole fraction; and c) molality. (ans 4.3%; 0.019; 1.08m)
6) Calculate the molarity and molality of an ammonia solution made up of 35.0 g NH3 in 75.0 g H2O.
The density of the solution is 0.982 g/mL. (ans: 18.38M; 27.5m)
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