Question 12.5 pts The solubility of sodium acetate is shown below (in units of g

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Question 12.5 pts

The solubility of sodium acetate is shown below (in units of grams per 100 mL water) at three temperatures.

Which of the following would result in a saturated solution? [Select all that apply.]

Question 22.5 pts

The solubility of sodium acetate is shown below (in units of grams per 100 mL water) at three temperatures.

Which of the following would result, at least temporarily, in a supersaturated solution? [Select all that apply.]

Question 32.5 pts

Consider a sample of water and air in a container. Which of the following changes will increase the amount of nitrogen dissolved in the water? [Select all that apply.]

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Question 42.5 pts

With all other conditions being equal, which of the following gases would you expect to have a largerHenry's law constant than N2?

Explanation / Answer

1. a) 56g in 100 mL at 30deg heated to 60 deg

Solubility at final temp 60 deg = 139g/100 ml. Therefore, unsaturated (56 g < 139 g)

b) 56g in 100 mL at 30deg

Solubility at temp 30 deg = 54.6 g/100 ml. Therefore, saturated (56 ~ 54.6 g).

c) 1Kg in 1L at 60deg or 100 g in 100 mL

Solubility at final temp 60 deg = 139g/100 ml. Therefore, unsaturated ( 100 g < 139 g).

d) 40g in 50 mL at 10deg or 80g in 100 mL

Solubility at 10 deg = 40.8g/100 ml. Therefore, supersaturated (80 g > 40.8 g).

2. Complete as described above.

3. According to the Le Chatlier's principle, when in a equillibrated system, there is a change in conc., p, v, Temp etc., the equillibrium shifts in the direction to counteract the change. In the given system there is an equillibrium between N2 (g) -> N2 (dissolved).

When the pressure or conc of N2 (g) increases, the system will reequillibrate increasing the concentration of dissolved N2, with an aim to decrease the conc. of N2 (g). Therefore, in the scenarios a, b and c, given in the options, the concentration of N2 (dissolved) increases.

a) When the pressure of the system is increased by decreasing its volume, PN2(g) increases; in order to decrease this excess pressure, the system will reequilibrate to dissolve more N2 in water.

b) When extra nitrogen gas is added to the container, the partial pressure of N2 (g) increases, thus again the system will reequilibrate in order to decrease this excess pressure increase by dissolving some of the N2 (g) in water.

c)When air in the container is replaced by pure N2, Partial pressure of N2 increases. Again, the system will re equillibrate to decrease the excess pressure by dissolving N2 in water.

d) When extra oxygen is added, there is no change in the partial pressure of N2. Therefore, no change occurs.

e) When the pressure of the system is decreased by increasing its volume, the partial pressure of N2 also decreases. Therefore, the system will readjust equilibrium in order to increase the partial pressure of N2 by converting dissolved N2 into N2 (g), thus decreasing N2 (dissolved).

3. k H, Henry's constant = P / C where, P is the partial pressure of gas and C is the concentration of gas in solution.

kH is inversely related to C. Therefore, the gases which have lower C than N2, would have higher values of kH. NH3 is the only gas with higher solubility in water among the options given, all other gases Ne, He and Xe have lower solubility in water , therefore, higher kH.

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