Chp. 13.4- Concentration Terms

Question 1

Molarity (M)

Answer 1

amt. (mol) of solute / volume (L) of solution

Question 2

Molality (m)

Answer 2

amt. (mol) of solute / mass (kg) of solvent

Question 3

Parts of mass

Answer 3

mass of solute / mass of solution

Question 4

Parts by volume

Answer 4

volume of solute / volume of solution

Question 5

Mole fraction (X)

Answer 5

amt. (mol) of solute / [amt. (mol) of solute + amt. (mol) of solvent]

Question 6

Sample Prob. 13.3. What is the molality of a solution prepared by dissolving 32.0 g of CaCl2 in 271 g of H20?

Answer 6

1.06 m CaCl2

Question 7

Mass % = mass of solute / mass of solution * 100

Answer 7

mass of solute / mass of solution * 100

Question 8

Volume %

Answer 8

volume of solute / volume of solution * 100

Question 9

Mole fraction (X) =

Answer 9

amt. (mol)of solute / [amt. (mol) of solute + amt. (mol) of solvent]

Question 10

Find the conc. of calcium ion (in ppm) in a 3.50-g pill that contains 40.5 mg of Ca2+.

Answer 10

1.16x10^4 ppm Ca2+

Question 11

The label on a 0.750-L bottle of Italian chianti indicates “11.5% alcohol by volume”. How many liters of alcohol does the bottle of wine contain?

Answer 11

0.0862 L

Question 12

A sample of rubbing alcohol contains 142 g of isopropyl alcohol (C3H7OH) and 58 g of H20. What are the mole fractions of alcohol and water?

Answer 12

X_C3H7OH = 0.423

X_H20 = 0.577

Question 13

If you were to make a 0.800m aqueous solution of glucose, what would be its boiling point and freezing point? (K_b = 0.51C/molarity, K_f=1.86C/molarity)

Answer 13

T_b = 100.41C

T_f = -1.49C

Question 14

The higher the molality, the _______ the freezing point.

Answer 14

Lower.

(Adding solute to a solvent will essentially dilute the solvent molecules, and according to Raoult’s law, this leads to a decrease in vapor pressure.

Question 15

The higher the molality, the _______ the boiling point.

Answer 15

Higher