Page 183 - Theory and Problems of BEGINNING CHEMISTRY

172 MOLARITY [CHAP. 11

Weight out 58.45 g of NaCl and dissolve it in a portion of water in a 250-mL volumetric flask (Fig. 11-2).
After the salt has dissolved, dilute the solution with water until the volume reaches the calibration mark
on the flask (250.0 mL). Mix the solution thoroughly by inverting and shaking the stoppered flask several
times.

11.30. What is the percent by mass of NaCl in 1.60 M NaCl solution? Assume that the solution has a density of 1.06 g/mL.
Ans. Percent by mass is the number of grams of NaCl in 100.0 g solution.
1.60 mol NaCl 58.5 g NaCl 1L 0.0883 g NaCl

=
1L 1 mol NaCl 1060 g solution 1 g solution
For 100.0 g of solution, multiply the numerator and denominator by 100:
0.0883 g NaCl 8.83 g NaCl
= = 8.83% NaCl
1 g solution 100 g solution
11.31. Which boxes of the conversion diagram (page 348) indicate the method of converting volumes of solutions to moles
of reactants and/or products and vice versa?
Ans. Boxes 2, 6, 12, and 15 with the intervening arrows.