c12 JWBS043-Rogers September 13, 2010 11:27 Printer Name: Yet to Come
PROBLEMS, EXAMPLES, AND EXERCISE 201the total mass of the solution. Exactly 10.00 g of NaCl was added to sufficient water
to make up 100.0 g of solution.
(a) What was the weight %?
(b) How many moles of NaCl were present in the solution?
(c) What was the molality of the solution?
(d) What was the molarity of the solution?
(e) Assuming a density of 1.0708 for this solution (CRC Handbook of Chemistry
and Physics, 2008–2009, 89th ed.), what was its volume?
(f) What was its molarity?
(g) What was the mole fraction of NaCl?
(h) What was the mole fraction of water?Problem 12.7
Exactly 10.0 g of B dissolved in 1000 g of A which has a molar massMAof 100 and
a density of 1.000 gave an osmotic pressure of 0.0500 atm at 300 K. Find the molar
mass of B.Problem 12.8
In the section on freezing point depression, theCRC Handbook of Chemistry and
Physics,2008–2009, 89th ed., defines the mass % as the mass of solute divided
by the total mass of the solution. Ammonia was infused into pure water until its
concentration was exactly 10.00 g of NH 3 per 100.0 g of solution.
(a) What was the weight %?
(b) How many moles of NH 3 were present in 100 g of the solution?
(c) What was the molality of the solution?
(d) What was the molarity of the solution?
(e) Assuming a density of 0.9575 for this solution (CRC Handbook of Chemistry
and Physics, 2008–2009, 89th ed.), what was its volume?
(f) What was its molarity?
(g) How many moles of water were there?
(h) If 1.8 mol of water are tied up by each mole of NH 3 , how many moles of free
water are there?
(i) How many grams is this?
(j) What is the molality of the solution of hydrated ammonia in water?Problem 12.9
As part of the derivation of the osmotic pressure equation (Section 12.7), the statement
was made that “In a dilute binary solution,lnx 1 ∼=−x 2 ”