Solutions Exam: Multiple Choice and Math

What is the freezing point of a solution containing 30.5 grams of NaCl in 255 grams of water? The Kf of water is -1.86 C/m

-7.63 C g->m 30.5/58.44= .522 moles molality= moles/kg .522/.255= 2.05 Tf=Kfmn Tf= (-1.86)(2.05)(2) Tf= -7.63 C

How many liters of 10.0 M NaOH are required to prepare 200 mL of a 0.450 M solution?

0.009L (.200)(.450)=10V -------------------- 10 =.009

A solution contains 85.0 g of NaNO3 and has a volume of 750 mL. Find the molarity of the solution.

1.33 M g->m 85g/ 85= 1 mol molarity= mol/L 1/.750= 1.33

What is the boiling point of a solution containing 5.50 grams of BaCl2 in 0.150 kg water? The Kb of water is 0.51 C/m

100.269 C g-> m 5.50/208.23= 0.0264moles molality= moles/kg 0.0264/0.150= 0.176 m Tb=Kbmn Tb= (.51)(.176)(3) Tb= .269 water boils at 100C so... 100+.269= 100.269C

Concentrated HCl is 11.7 M. How much of the HCl would be required to prepare 350mL of a 4M solution?

120. mL 11.7V= 350(4) 11.7V=1400 ------------ 11.7 119.6mL

How many milliliters of 6.00 M HCl are needed to prepare 350 mL of a 2.75 M solution?

160. mL (350)(2.75)=6V ----------------- 6V =160.42mL

Refer to the solubility graph. How much potassium iodide will dissolve at 60C?

230 g

How much sodium nitrate can be dissolved in 300 grams of water at 25 C?

270 g

Iron (III) chloride can be produced by reacting Fe2O3 with a hydrochloric acid (HCl), solution. How many milliliters of a 6.00 M HCl solution are needed to react with excess Fe2O3 to produce 16.5g of FeCl2? The other product is water.

50.9 mL HCl Fe2O3+ 6 HCl -> 2 FeCl3 + 3 H2O 16.5g/162.2g x 6mol/2mol x 1L/6.00mol x 1000mL/1L =50.9

At what minimum temperature, can 110 grams of potassium nitrate be dissolved in 100 mL of water?

60C

What is the net ionic equation for the reaction between CuCl2 (aq) + NaOH (aq)?

Cu2+ (aq) + 2 OH- (aq) -> Cu(OH)2 (s)

Which solute is present in aqueous solution mostly as molecules rather than as ions and is a weak conductor of electricity?

a. a weak electrolyte

The separation of ions that occurs when an ionic compound dissolves is called

a. dissociation

A substance whose water solution conducts a current is a(n)

a. electrolyte

NaCl dissociates into ions completely when it is dissolved. It would be classified as a:

a. strong electrolyte

Refer to the solubility curve on the back of this exam. If a solution contains 70 g of potassium chlorate in 100 g water at 60 C, it is

a. supersaturated

What is the molality of a solution that contains 5.10 mol KNO3 in 4.47 kg water?

b. 1.14 m molality= mol/kg 5.10/4.47= 1.14

Which of the following pairs of solutions produce a precipitate when combined?

b. NH4Cl and AgNO3

As temperature increases, solubility of gases in liquids

b. decreases

A solution containing 200 grams of potassium iodide at 35C would be considered to be

b. supersaturated

A solution containing 60 grams of sodium nitrate at 20C would be considered to be

b. unsaturated

What is the approximate freezing-point depression of a 0.020 m aqueous NaBr solution? Kf is -1.86 C/m

c. -0.074 C Tf= Kf(m)(n) Tf= (-1.86)(0.020)(2) Tf= -0.0744

What is the molarity of a solution that contains 0.202 mol KCl in 7.98 L solution?

c. 0.0253 M molarity= mol/L .202/7.98= .0253

What is the molarity of a solution that contains 125g NaCl in 4.00 L solution?

c. 0.535 M molarity= mol/L 125g/58.44= 2.14 mol 2.14 mol/ 4.00L= 0.535

The concentration of a water solution of NaCl is 2.48 m, and it contains 806 g of water. How much NaCl is in the solution?

c. 117g molality: moles/ kg of solvent 2.48= ?/ .806kg or 2.48 x .806= 1.99 moles 1.99 mols x 58.44= 116.8 g

Which of the following is NOT a net ionic equation?

c. Fe2+(aq) + 2 Cl-(aq) +2 OH-(aq) -> Fe(OH)2 (s) + 2 Cl-(aq)

Compared with a 0.01 m sugar solution and a 0.01 m KCl solution has

c. about twice the freezing-point depression

As temperature increases, solubility of solids in liquids

c. always increases

How does adding solute to a solvent affect the vapor pressure of the solvent?

c. lowers it

50 grams of NaCl is dissolved in 254 mL of water. The NaCl is considered to be the

c. solute

Colligative properties depend on

c. the concentration of the solute particles

What is the boiling point elevation of a solution made from 10.0 g of a nonelectrolyte solute and 300.0 g of water? The molar mass of the solute is 50.0 g and the molal boiling point constant for water is 0.51C

d. 0.34C g -> m 10g/ 50= 0.2 moles molality= moles/ kg 0.2/.300 x .51= .34C

Which of the following would not increase the solubility rate of a solid substance?

d. increase in pressure

Ions are formed from solute molecules by the action of the solvent in a process called

d. ionization