1.) Indicate which aqueous solution has the lowest vapor pressure: a. 0.2 M MgCl

Question

1.) Indicate which aqueous solution has the lowest vapor pressure:

a. 0.2 M MgCl2   b. 0.1 M MgCl2   c. 0.2 M NaCl d. 0.1 M KCl e. 0.1 M Na2CO3

2.) Indicate which aqueous solution has the fastest evaporation rate.

a. 0.2 M MgCl2   b. 0.1 M MgCl2   c. 0.2 M NaCl d. 0.1 M KCl e. 0.1 M Na2CO3

3.) What is the molarity of a sucrose (C12H22O11) solution that produces an osmotic pressure of 2.65 atm at 25°C?

a. 0.0349 M   b. 0.108 M   c. 0.127 M   d. 0.398 M   e. 0.0127 M

4.) The pressure of carbon dioxide in a beer bottle is about 2 atm. At this pressure about 0.15 g of carbon dioxide dissolves in 100 mL of beer. How much carbon dioxide remains dissolved in 100 mL after the bottle is opened? The partial pressure of carbon dioxide is 2.0 ´ 10-4 atm. a. 3.8 ´ 10-3 g b. 0.15 g c. 6.0 ´ 10-5 g d. 1.5 ´ 10-5 g e. 3.0 ´ 10-4 g

5.) Caryophyllene, a nonelectrolyte, is one of the compounds responsible for the flavor of cloves. A 207 mg sample of caryophyllene was dissolved in 1.00 g of chloroform (Kb = 3.63°C/m), increasing the boiling point of chloroform by 3.68°C. What is the molar mass of caryophyllene? a. 164 g/mol b. 219 g/mol c. 193 g/mol d. 204 g/mol e. 156 g/mol

6.) Which of the following would be most effective in melting ice on a sidewalk?

a. 1 kg KCl b. 1 kg CaCl2   c. 1 kg NaCl d. 1 kg MgCl2 e. 1 kg CuCl

7.) Given the same number of moles of each of the following substances, which one would be most effective in melting ice on a sidewalk?

a. KCl b. CaCl2   c. MgCl2   d. (NH4)3PO4   e. NaCl

8.) If water contains about 42 mg of oxygen per liter at 20°C and 1.0 atm, what would be the value of Henry's law constant for oxygen dissolving in water? The mole fraction of oxygen in air is 0.21.

a. 1.9 ´ 10-2 mol/(L atm) b. 6.3 ´ 10-3 mol/(L atm) c. 0.25 mol/(L atm) d. 0.010 mol/(L atm) e. 1.3 ´ 10-3 mol/(L atm)

9.) What is the molarity of a solution of 10% by mass cadmium sulfate, CdSO4 (molar mass = 208.46 g/mol) by mass? The density of the solution is 1.10 g/mL. a. 0.048 M b. 0.528 M c. 0.479 M d. 0.436 M e. 22.9 M

10.)  Determine the molal concentration of a sugar solution in water that has a freezing point of -2.1°C. Kf = 1.86°C/m for water.

a. -1.13 m   b. -3.91 m   c. 1.13 m   d. 0.113 m   e. 3.91 m

11.) Eugenol is a nonelectrolyte that contributes to the flavor of spices such as clove, nutmeg, cinnamon, and basil. A 328 mg sample of eugenol was dissolved in 10.0 g of chloroform
(Kb = 3.63°C/m), increasing the boiling point of the chloroform by 0.726°C. What is the molar
mass of eugenol? a. 82 g/mol b. 164 g/mol c. 182 g/mol d. 363 g/mol e. 328 g/mol

Explanation / Answer

I am solving the first two problems, please split to get the remaining answers

1) 0.2 M MgCl2 = 0.6 moles of solute in 1L of watet ( since 1L will give one Mg+ and 2Cl-)

0.1 M MgCl2 = 0.3 moles of solute in 1L of water

0.2M NaCl = 0.4 moles of solute (since 1L will give one mole of Na+ and one mole of Cl-)

0.1M KCl = 0.2 moles of solute (since 1L will give one mole of K+ and one mole of Cl-)

0.1M Na2CO3) = 0.3 moles of soute ( since 1L will given 2 moles of Na+ and one mole of CO3(2-))

Hence the lowest vapor pressure will be of KCl, therefore the correct answer is Option D

2) The correct answer is Option D, since the lowest vapor pressure one will be the fastest to evaporate

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