Question

(1). Which of the following molecules is most soluble in hexane, C6H14?

NH3

CH3NH2

CH3OH

CH3CH3

H2O

(2). Which of the following molecules is most soluble in methanol CH3OH?

N(CH3)3

CH3NH2

CH3COCH3

CH3CH2CH2CH2CH2CH3

HOCH2CH2OH

(3). Calculate the concentration of CO2 in a soft drink that is bottled with a partial pressure of CO2 of 5 atm over the liquid at 25 °C. The Henry’s Law constant for CO2 in water at this temperature is 3.12 ´ 10–2 mol L–1 atm–1.

1. 0.16

2. 0.26

3. 1.26

4. 1.16

5. 0.56

(4). Calculate the concentration of CO2 in a soft drink after the bottle is opened and equilibrates at 25 °C under a partial pressure of CO2 of 4.0 ´ 10–4 atm. (Henry's Law)

1. 5.2 x 10^–4  mol CO₂/L

2. 1.9 x 10^–4  mol CO₂/L

3. 1.2 x 10^–4  mol CO₂/L

4. 2.2 x 10^–4  mol CO₂/L

5. 6.2 x 10^–4  mol CO₂/L

(5). What is the concentration of dissolved nitrogen in a solution that is saturated in N2 at 2.0 atm? k_H= 8.42 × 10-7 mol L^–1 atm^–1

1.      1.7 × 10^–6 mol L^–1

2.      1.1 × 10^–6 mol L^–1

3.       2.1 × 10^–6 mol L^–1

4.      2.7 × 10^–6 mol L^–1  

5.      3.1 × 10^–6 mol L^–1

(6). How many grams of oxygen gas at 1.0 atm will dissolve in 10.0 L of water at 25 °C if Henry’s constant is 1.3 × 10–3 mol L^–1 atm^–1 at this temperature?

0.42 g

0.013 g

0.042 g

0.21 g

2.4 g

(7). The solubility of O2 in water is approximately 0.00380 g L-1 when the temperature is 25.0 °C and the partial pressure of gaseous oxygen is 760 torr. What will the solubility of oxygen be if the pressure is adjusted to 1000 torr?

0.00289 g L^-1

0.00500 g L^-1

1.49 g L^-1

2.89 x 103 g L^-1

3.46 x 103 g L^-1

(8). What is the molality of 50.0% (w/w) sodium hydroxide solution?

Molar Masses  H₂O: 18.02 g/mol ; NaOH: 40.00 g/mol

 0.500 m

 1.25 m

 0.025 m

 25 m

 50 m

(9). What is the molarity of the 50%(w/w) solution if its density is 1.529 g/mL?

19 M

1.25 M

1.9 M

0.76 M

2.9 M

(10). What mass of NH4Cl must be dissolved in 100 mL of H2O to make a 0.250 M solution?

1340 g

21.40 g

13.4 g

1.34 g

2.14 g

(11). n-Hexane and n-heptane are miscible. If the vapor pressure of pure hexane is 151.28 mm Hg, and heptane is 45.67 at 25 °C, which equation can be used to determine the mole fraction of hexane in the mixture if the mixture’s vapor pressure is 145.5 mm Hg?

1. X (151.28 mmHg) = 145.5 mmHg

2. X (151.28 mmHg) + (X )(45.67 mm Hg) = 145.5 mmHg

3. X (151.28 mmHg) + (1 – X )(45.67 mm Hg) = 145.5 mm Hg

4. None of these

(12). According to the Sierra™ Antifreeze literature, the freezing point of a 40/60 solution of Sierra antifreeze and water is – 4 °F. What is the molality of the solution? (K_fp = 1.86 ^oCm^-1)

1.   3 m

2.   5 m

3.   7 m

4.   9 m

5.   11 m

who can help me with these questions??

Answer 1