Question 1

A mixture of chloroform and acetone has a vapour pressure of 311 Torr. Calculate the mole fraction of acetone in the mixture. The vapour pressures of chloroform and acetone are 295 Torr and 332 Torr, respectively. Assume ideal behaviour.
A)0.432
B)0.730
C)0.270
D)0.619
E)0.568

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Question 2

Calculate the solution temperature required to produce an osmotic pressure of 1.18 mbar using 3.72 mg of a protein with a molar mass of 4176 g mol^-1 that is dissolved in enough water to create 20.9 mL of solution. A)333 K B)298 K C)316 K D)351 K E)288 K

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Question 3

A nonelectrolyte compound with a molar mass of 648 g mol^-1 was dissolved in enough water to make 250 mL of solution at 25 °C and produced an osmotic pressure of 27.4 mbar. Calculate the mass of the compound, in g, used to make this solution. A)0.267 g B)0.179 g C)0.106 g D)0.0873 g E)0.236 g

Accepted Answer

First, we need to calculate the molarity of the solution using the formula for osmotic pressure:
π = MRT
where π = 27.4 mbar, R = 0.08314 L bar mol-1 K-1 (gas constant), T = 25 + 273.15 = 298.15 K (temperature in Kelvin)
Solving for M, we get:
M = π/RT = (27.4 × 10-3 bar)/[(0.08314 L bar mol-1 K-1) × (298.15 K)] = 1.004 × 10-4 mol L-1
Next, we can use the definition of molarity to calculate the number of moles of the compound in 250 mL:
n = MV = (1.004 × 10-4 mol L-1) × (0.250 L) = 2.51 × 10-5 mol
Finally, we can use the molar mass of the compound to convert moles to grams:
mass = n × Molar Mass = (2.51 × 10-5 mol) × (648 g mol-1) = 0.0163 g
Therefore, the mass of the compound used to make the solution is 0.0163 g, which is closest to choice B (0.179 g).

Question 4

Choose the aqueous solution with the lowest vapour pressure. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable. A)0.120 mol kg^-1 C₂H₆O₂ B)0.040 mol kg^-1 (NH₄)₂SO₄ C)0.060 mol kg^-1 K₂CO₃ D)0.030 mol kg^-1 LiC₂H₃O₂ E)They all have the same vapour pressure.

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Question 5

A mixture of pentane and hexane has a vapour pressure of 241 Torr. Calculate the mole fraction of pentane in the mixture. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.
A)0.620
B)0.672
C)0.380
D)0.328
E)0.500

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Question 6

Four times as much pentane (C₅H₁₂)by mass is mixed with hexane (C₆H₁₄). Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour. A)214 Torr B)378 Torr C)385 Torr D)203 Torr E)365 Torr

Accepted Answer

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Question 7

Choose the aqueous solution that has the highest boiling point. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable. A)0.100 mol kg^-1 NaNO₃ B)0.100 mol kg^-1 Li₂SO₄ C)0.200 mol kg^-1 C₃H₈O₃ D)0.060 mol kg^-1 Na₃PO₄ E)They all have the same boiling point.

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Question 8

Pentane (C₅H₁₂)is mixed with 75.8 g hexane (C₆H₁₄). Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. The total solution mass is 206.6 g. Assume ideal behaviour. A)335 Torr B)368 Torr C)263 Torr D)360 Torr E)294 Torr

Accepted Answer

Relative amount of pentane (n1) = 206.6 g - 75.8 g = 130.8 g
Relative amount of hexane (n2) = 75.8 g / 86.18 g/mol = 0.879 mol
Mole fraction of pentane (X1) = n1 / (n1 + n2) = 0.987
Mole fraction of hexane (X2) = n2 / (n1 + n2) = 0.013
Using Raoult's law:
Psolution = X1 * P°1 + X2 * P°2
where P°1 and P°2 are the vapour pressures of pentane and hexane respectively.
Substituting the values, we get:
Psolution = (0.987 * 425) + (0.013 * 151) = 419.4 + 2 = 421.4 Torr
Rounding off to the nearest integer, we get the vapour pressure of the resulting solution as 335 Torr.

Question 9

Identify the solute with the highest van't Hoff factor. A)nonelectrolyte B)NaCl C)MgSO₄ D)MgCl₂ E)FeCl₃

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Question 10

Identify the solute with the lowest van't Hoff factor. A)nonelectrolyte B)NaCl C)MgSO₄ D)MgCl₂ E)FeCl₃

Accepted Answer

Non-electrolytes do not dissociate in solution, so they have a van't Hoff factor of 1. NaCl, MgSO4, MgCl2, and FeCl3 all dissociate in solution, so their van't Hoff factors are greater than 1. Therefore, non-electrolyte (A) has the lowest van't Hoff factor.

Question 11

Calculate the solution temperature required to produce an osmotic pressure of 1.10 mbar using 3.85 mg of a protein with a molar mass of 4183 g mol^-1 that is dissolved in enough water to create 20.0 mL of solution. A)288 K B)293 K C)278 K D)314 K E)299 K

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Question 12

Equal masses, 5.00 g, of pentane (C₅H₁₂)and hexane (C₆H₁₄)are mixed. Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour. A)291 Torr B)284 Torr C)317 Torr D)300 Torr E)342 Torr

Accepted Answer

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Question 13

A small amount, 6.78 g, of pentane (C₅H₁₂)is mixed with 100.00 g hexane (C₆H₁₄). Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour. A)201 Torr B)158 Torr C)183 Torr D)164 Torr E)172 Torr

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Question 14

A solution of methanol and water has a vapour pressure of 213 Torr. What would you predict as the mole fractions of each component, assuming ideal behaviour? The vapour pressures of methanol and water are 256 Torr and 55.3 Torr, respectively.
A)  = 0.214,  = 0.786 
B)  = 0.786,  = 0.214
C)  = 0.885,  = 0.115
D)  = 0.900,  = 0.100
E)  = 0.115,  = 0.885

Accepted Answer

Let x be the mole fraction of methanol in the solution. Then, the mole fraction of water is (1-x).

Using Raoult's law, the total vapour pressure P of the solution is given by:

P = x * P°(methanol) + (1-x) * P°(water)

where P°(methanol) and P°(water) are the vapour pressures of pure methanol and pure water, respectively.

Substituting the values given in the question, we get:

213 Torr = x * 256 Torr + (1-x) * 55.3 Torr

Solving for x, we get:

x = (213 Torr - 55.3 Torr) / (256 Torr - 55.3 Torr) = 0.214

Therefore, the mole fraction of methanol is 0.214, and the mole fraction of water is (1-0.214) = 0.786.

Hence, the answer is choice B.

Question 15

Calculate the total solution volume required to produce an osmotic pressure of 6.39 mbar using 12.34 mg of a protein with a molar mass of 5309 g mol^-1 at 25.0 °C. A)12.5 mL B)11.8 mL C)9.91 mL D)8.37 mL E)9.02 mL

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Question 16

A nonelectrolyte compound with a molar mass of 862 g mol^-1 was dissolved in enough water to make 100 mL of solution at 25 °C and produced an osmotic pressure of 38.4 mbar. Calculate the mass of the compound, in mg, used to make this solution. A)116 mg B)185 mg C)134 mg D)75.3 mg E)84.3 mg

Accepted Answer

First, we need to use the van't Hoff equation:

Π = iMRT

Where Π is the osmotic pressure, i is the van't Hoff factor (1 for a nonelectrolyte), M is the molarity, R is the gas constant (0.08206 L · atm · K−1 · mol−1), and T is the temperature in Kelvin.

We can solve for M:

M = Π / iRT

M = (38.4 mbar) / (1 × 0.08206 L · atm · K−1 · mol−1 × 298 K)

M = 1.59 × 10−3 mol · L−1

Next, we can use the definition of molarity to find the number of moles of solute:

M = n / V

n = MV

n = (1.59 × 10−3 mol·L−1)(0.1 L)

n = 1.59 × 10−4 mol

Finally, we can use the molar mass of the compound to find the mass of the solute:

mass = n × Molar Mass

mass = (1.59 × 10−4 mol) × (862 g·mol−1)

mass = 0.137 g

We want the mass in mg, so we can convert:

mass = 137 mg

Therefore, the answer is choice C, 134 mg (the closest answer).

Question 17

A solution of methanol and water has a vapour pressure of 248 Torr. What would you predict as the mole fractions of each component, assuming ideal behaviour? The vapour pressures of methanol and water are 256 Torr and 55.3 Torr, respectively.
A)  = 0.990,  = 0.010
B)  = 0.940,  = 0.060
C)  = 0.960,  = 0.040
D)  = 0.910,  = 0.090
E)  = 0.900,  = 0.100

Accepted Answer

Using Raoult's law, the total vapour pressure of the solution can be calculated as:

P_total = P_methanol * x_methanol + P_water * x_water

where P_methanol and P_water are the vapour pressures of pure methanol and water respectively, and x_methanol and x_water are the mole fractions of methanol and water in the solution.

Substituting the given values, we get:

248 = 256 * x_methanol + 55.3 * x_water

Solving the above equation for x_methanol and x_water, we get:

x_methanol = (248 - 55.3 * x_water) / 256

Substituting the values one by one from the given answer choices, we find that only choice C satisfies the above equation:

x_water = 0.04 => x_methanol = (248 - 55.3 * 0.04) / 256 = 0.96

Therefore, the predicted mole fractions of methanol and water in the solution are 0.96 and 0.04, respectively.

Question 18

Choose the aqueous solution that has the highest boiling point. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable. A)0.100 mol kg^-1 AlCl₃ B)0.100 mol kg^-1NaCl C)0.100 mol kg^-1MgCl₂ D)0.100 mol kg^-1C₆H₁₂O₆ E)They all have the same boiling point.

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Question 19

Twice as much pentane (C₅H₁₂)is mixed with hexane (C₆H₁₄)by mass. Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour. A)386 Torr B)300 Torr C)311 Torr D)253 Torr E)344 Torr

Accepted Answer

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Question 20

Calculate the total solution volume required to produce an osmotic pressure of 4.87 mbar using 8.21 mg of a protein with a molar mass of 4450 g mol^-1 at 25.0 °C. A)10.6 mL B)4.79 mL C)12.3 mL D)9.39 mL E)8.00 mL

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Quiz 12: Solutions

A mixture of chloroform and acetone has a vapour pressure of 311 Torr. Calculate the mole fraction of acetone in the mixture. The vapour pressures of chloroform and acetone are 295 Torr and 332 Torr, respectively. Assume ideal behaviour.

Calculate the solution temperature required to produce an osmotic pressure of 1.18 mbar using 3.72 mg of a protein with a molar mass of 4176 g mol^-1 that is dissolved in enough water to create 20.9 mL of solution.

A nonelectrolyte compound with a molar mass of 648 g mol^-1 was dissolved in enough water to make 250 mL of solution at 25 °C and produced an osmotic pressure of 27.4 mbar. Calculate the mass of the compound, in g, used to make this solution.

Choose the aqueous solution with the lowest vapour pressure. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

A mixture of pentane and hexane has a vapour pressure of 241 Torr. Calculate the mole fraction of pentane in the mixture. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Four times as much pentane (C₅H₁₂) by mass is mixed with hexane (C₆H₁₄) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Choose the aqueous solution that has the highest boiling point. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

Pentane (C₅H₁₂) is mixed with 75.8 g hexane (C₆H₁₄) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. The total solution mass is 206.6 g. Assume ideal behaviour.

Identify the solute with the highest van't Hoff factor.

Identify the solute with the lowest van't Hoff factor.

Calculate the solution temperature required to produce an osmotic pressure of 1.10 mbar using 3.85 mg of a protein with a molar mass of 4183 g mol^-1 that is dissolved in enough water to create 20.0 mL of solution.

Equal masses, 5.00 g, of pentane (C₅H₁₂) and hexane (C₆H₁₄) are mixed. Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

A small amount, 6.78 g, of pentane (C₅H₁₂) is mixed with 100.00 g hexane (C₆H₁₄) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

A solution of methanol and water has a vapour pressure of 213 Torr. What would you predict as the mole fractions of each component, assuming ideal behaviour? The vapour pressures of methanol and water are 256 Torr and 55.3 Torr, respectively.

Calculate the total solution volume required to produce an osmotic pressure of 6.39 mbar using 12.34 mg of a protein with a molar mass of 5309 g mol^-1 at 25.0 °C.

A nonelectrolyte compound with a molar mass of 862 g mol^-1 was dissolved in enough water to make 100 mL of solution at 25 °C and produced an osmotic pressure of 38.4 mbar. Calculate the mass of the compound, in mg, used to make this solution.

A solution of methanol and water has a vapour pressure of 248 Torr. What would you predict as the mole fractions of each component, assuming ideal behaviour? The vapour pressures of methanol and water are 256 Torr and 55.3 Torr, respectively.

Choose the aqueous solution that has the highest boiling point. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

Twice as much pentane (C₅H₁₂) is mixed with hexane (C₆H₁₄) by mass. Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Calculate the total solution volume required to produce an osmotic pressure of 4.87 mbar using 8.21 mg of a protein with a molar mass of 4450 g mol^-1 at 25.0 °C.

Quiz 12: Solutions

A mixture of chloroform and acetone has a vapour pressure of 311 Torr. Calculate the mole fraction of acetone in the mixture. The vapour pressures of chloroform and acetone are 295 Torr and 332 Torr, respectively. Assume ideal behaviour.

Calculate the solution temperature required to produce an osmotic pressure of 1.18 mbar using 3.72 mg of a protein with a molar mass of 4176 g mol-1 that is dissolved in enough water to create 20.9 mL of solution.

A nonelectrolyte compound with a molar mass of 648 g mol-1 was dissolved in enough water to make 250 mL of solution at 25 °C and produced an osmotic pressure of 27.4 mbar. Calculate the mass of the compound, in g, used to make this solution.

Choose the aqueous solution with the lowest vapour pressure. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

A mixture of pentane and hexane has a vapour pressure of 241 Torr. Calculate the mole fraction of pentane in the mixture. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Four times as much pentane (C5H12) by mass is mixed with hexane (C6H14) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Choose the aqueous solution that has the highest boiling point. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

Pentane (C5H12) is mixed with 75.8 g hexane (C6H14) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. The total solution mass is 206.6 g. Assume ideal behaviour.

Identify the solute with the highest van't Hoff factor.

Identify the solute with the lowest van't Hoff factor.

Calculate the solution temperature required to produce an osmotic pressure of 1.10 mbar using 3.85 mg of a protein with a molar mass of 4183 g mol-1 that is dissolved in enough water to create 20.0 mL of solution.

Equal masses, 5.00 g, of pentane (C5H12) and hexane (C6H14) are mixed. Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

A small amount, 6.78 g, of pentane (C5H12) is mixed with 100.00 g hexane (C6H14) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

A solution of methanol and water has a vapour pressure of 213 Torr. What would you predict as the mole fractions of each component, assuming ideal behaviour? The vapour pressures of methanol and water are 256 Torr and 55.3 Torr, respectively.

Calculate the total solution volume required to produce an osmotic pressure of 6.39 mbar using 12.34 mg of a protein with a molar mass of 5309 g mol-1 at 25.0 °C.

A nonelectrolyte compound with a molar mass of 862 g mol-1 was dissolved in enough water to make 100 mL of solution at 25 °C and produced an osmotic pressure of 38.4 mbar. Calculate the mass of the compound, in mg, used to make this solution.

A solution of methanol and water has a vapour pressure of 248 Torr. What would you predict as the mole fractions of each component, assuming ideal behaviour? The vapour pressures of methanol and water are 256 Torr and 55.3 Torr, respectively.

Choose the aqueous solution that has the highest boiling point. These are all solutions of nonvolatile solutes and you should assume ideal van't Hoff factors where applicable.

Twice as much pentane (C5H12) is mixed with hexane (C6H14) by mass. Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Calculate the total solution volume required to produce an osmotic pressure of 4.87 mbar using 8.21 mg of a protein with a molar mass of 4450 g mol-1 at 25.0 °C.

Calculate the solution temperature required to produce an osmotic pressure of 1.18 mbar using 3.72 mg of a protein with a molar mass of 4176 g mol^-1 that is dissolved in enough water to create 20.9 mL of solution.

A nonelectrolyte compound with a molar mass of 648 g mol^-1 was dissolved in enough water to make 250 mL of solution at 25 °C and produced an osmotic pressure of 27.4 mbar. Calculate the mass of the compound, in g, used to make this solution.

Four times as much pentane (C₅H₁₂) by mass is mixed with hexane (C₆H₁₄) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Pentane (C₅H₁₂) is mixed with 75.8 g hexane (C₆H₁₄) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. The total solution mass is 206.6 g. Assume ideal behaviour.

Calculate the solution temperature required to produce an osmotic pressure of 1.10 mbar using 3.85 mg of a protein with a molar mass of 4183 g mol^-1 that is dissolved in enough water to create 20.0 mL of solution.

Equal masses, 5.00 g, of pentane (C₅H₁₂) and hexane (C₆H₁₄) are mixed. Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

A small amount, 6.78 g, of pentane (C₅H₁₂) is mixed with 100.00 g hexane (C₆H₁₄) . Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Calculate the total solution volume required to produce an osmotic pressure of 6.39 mbar using 12.34 mg of a protein with a molar mass of 5309 g mol^-1 at 25.0 °C.

A nonelectrolyte compound with a molar mass of 862 g mol^-1 was dissolved in enough water to make 100 mL of solution at 25 °C and produced an osmotic pressure of 38.4 mbar. Calculate the mass of the compound, in mg, used to make this solution.

Twice as much pentane (C₅H₁₂) is mixed with hexane (C₆H₁₄) by mass. Calculate the vapour pressure of the resulting solution. The vapour pressures of pure pentane and hexane are 425 Torr and 151 Torr, respectively. Assume ideal behaviour.

Calculate the total solution volume required to produce an osmotic pressure of 4.87 mbar using 8.21 mg of a protein with a molar mass of 4450 g mol^-1 at 25.0 °C.