Question 1

Cinnamaldehyde ( = 132.15 g/mol)is used as a flavoring agent.What mass of cinnamaldehyde must be added to 175 g of ethanol to give a solution whose boiling point is 82.7°C? K_b = 1.22°C/m,boiling point of pure ethanol = 78.5°C A)62.4 g B)67.8 g C)76.2 g D)78.5 g E)79.6 g

Accepted Answer

The answer of Cinnamaldehyde ( 
= 132.15 g/mol)is used as...

Question 2

Lysine is an amino acid that is an essential part of nutrition but which is not synthesized by the human body.What is the molar mass of lysine if 750.0 mL of a solution containing 8.60 g of lysine has an osmotic pressure of 1.918 atm?
T = 25.0°C
A)110.g/mol
B)146 g/mol
C)220.g/mol
D)1340 g/mol
E)1780 g/mol

Accepted Answer

First, we need to find the number of moles of lysine in the solution:

n = mass/molar mass
n = 8.60 g/molar mass

Next, we need to convert the volume of the solution to liters and use the formula for osmotic pressure:

π = MRT
M = π/RT

where π is the osmotic pressure in atm, R is the gas constant (0.08206 L•atm/(mol•K)), and T is the temperature in Kelvin.

Converting the temperature to Kelvin:

T = 25.0°C + 273.15
T = 298.15 K

Converting the volume of the solution to liters:

750.0 mL = 0.750 L

Substituting the given values into the formula for M:

M = π/RT
M = 1.918 atm/(0.08206 L•atm/(mol•K)•298.15 K)
M = 0.0814 mol/L

Finally, we can solve for the molar mass of lysine:

n = M•V
8.60 g/molar mass = 0.0814 mol/L•0.750 L
molar mass = 147.8 g/mol ≈ 146 g/mol

Therefore, the best choice is B) 146 g/mol.

Question 3

Human blood has a molar concentration of solutes of 0.30 M.What is the osmotic pressure of blood at 25°C?
A)0.012 atm
B)0.62 atm
C)6.8 atm
D)7.3 atm
E)>10.atm

Accepted Answer

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Question 4

Safrole is used as a topical antiseptic.Calculate the vapor pressure of a solution prepared by dissolving 0.75 mol of safrole in 950 g of ethanol ( = 46.07 g/mol).P°_ethanol = 50.0 torr at 25°C. A)1.8 torr B)11 torr C)15 torr D)40 torr E)48 torr

Accepted Answer

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Question 5

Determine the freezing point of a solution which contains 0.31 mol of sucrose in 175 g of water.K_f = 1.86°C/m A)3.3°C B)1.1°C C)0.0°C D)-1.1°C E)-3.3°C

Accepted Answer

The answer of Determine the freezing point of a solution...

Question 6

Two aqueous solutions are prepared: 2.0 m Cu(NO₃)₂ and 2.0 m NaBr.Which of the following statements is true? A)The Cu(NO₃)₂ solution has a higher vapor pressure and lower freezing point than the NaBr solution. B)The Cu(NO₃)₂ solution has a higher vapor pressure and higher freezing point than the NaBr solution. C)The Cu(NO₃)₂ solution has a lower vapor pressure and lower freezing point than the NaBr solution. D)The Cu(NO₃)₂ solution has a lower vapor pressure and higher freezing point than the NaBr solution. E)None of these statements is true.

Accepted Answer

The Cu(NO3)2 solution dissociates into three ions (Cu^2+ and 2 NO3^-), while NaBr dissociates into two ions (Na^+ and Br^-). More ions result in a lower vapor pressure and lower freezing point for the Cu(NO3)2 solution compared to the NaBr solution.

Question 7

Calculate the freezing point of a solution made by dissolving 3.50 g of potassium chloride ( = 74.55 g/mol)in 100.0 g of water.Assume ideal behavior for the solution;K_f = 1.86°C/m. A)-1.7°C B)-0.9°C C)0.0°C D)0.9°C E)1.7°C

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Question 8

Which of the following aqueous solutions will have the lowest osmotic pressure? A)0.10 m KOH B)0.10 m RbCl C)0.05 m CaSO₄ D)0.05 m BaCl₂ E)0.10 m K₂SO₄

Accepted Answer

Osmotic pressure depends on the total concentration of solute particles in solution. KOH, RbCl, and K2SO4 dissociate into ions in solution, increasing the number of particles. CaSO4 and BaCl2 also dissociate, but the concentration of CaSO4 (0.05 m) is lower than the others, resulting in fewer particles and thus the lowest osmotic pressure.

Question 9

Hexachlorophene is used as a disinfectant in germicidal soaps.What mass of hexachlorophene ( = 406.9 g/mol)must be added to 125 g of chloroform to give a solution with a boiling point of 62.60°C? K_b = 3.63°C/m,boiling point of pure chloroform = 61.70°C A)12.6 g B)17.2 g C)31.0 g D)34.4 g E)101 g

Accepted Answer

The answer of Hexachlorophene is used as a disinfectant in...

Question 10

Dimethylglyoxime,DMG,is an organic compound used to test for aqueous nickel(II)ions.A solution prepared by dissolving 65.0 g of DMG in 375 g of ethanol boils at 80.3°C.What is the molar mass of DMG? K_b = 1.22°C/m,boiling point of pure ethanol = 78.5°C A)44.1 g/mol B)65.8 g/mol C)117 g/mol D)131.6 g/mol E)553 g/mol

Accepted Answer

First, we need to calculate the boiling point elevation of the solution compared to pure ethanol:

ΔT = i*K*m
where ΔT is the boiling point elevation, i is the van't Hoff factor (the number of particles into which DMG dissociates in solution, which we will assume to be 1), K is the molal boiling point constant of the solvent (ethanol), and m is the molality of the solution.

We can calculate m as follows:

m = moles of DMG / mass of solvent (in kg)

To calculate the moles of DMG, we need to use the given amount of DMG and its formula:

65.0 g DMG / (2*14.01 g/mol + 4*12.01 g/mol + 4*1.01 g/mol + 2*16.00 g/mol) = 0.319 mol DMG

Now we can calculate the molality:

m = 0.319 mol / 0.375 kg = 0.850 m

Finally, we can calculate the boiling point elevation:

ΔT = 1 * 1.22°C/m * 0.850 m = 1.04°C

The boiling point of the solution is therefore:

boiling point = 80.3°C + 1.04°C = 81.3°C

To calculate the molar mass of DMG, we can use the formula for the boiling point elevation of a nonvolatile solute:

ΔT = K*m*(1 - (1/moles of solute)*mass of solvent/(molar mass of solute))

Solving for the molar mass of DMG:

molar mass of DMG = mass of solute / moles of solute

mass of solute = 65.0 g
moles of solute = 0.319 mol
mass of solvent = 375 g
K = 1.22°C/m
ΔT = 1.04°C
boiling point of pure solvent = 78.5°C

Substituting into the formula and solving:

1.04 = 1.22*(0.850)*(1 - (1/0.319)*0.375/molar mass of DMG)
molar mass of DMG = 117 g/mol

Question 11

Diethyl ether has a vapor pressure of 400.0 torr at 18°C.When a sample of benzoic acid is dissolved in ether,the vapor pressure of the solution is 342 torr.What is the mole fraction of benzoic acid in the solution?
A)0.0169
B)0.0197
C)0.145
D)0.855
E)None of these choices is correct.

Accepted Answer

Using Raoult's Law:
Ptotal = Xether * Pether + Xbenzoic acid * Pbenzoic acid

Solving for Xbenzoic acid:
Xbenzoic acid = (Ptotal - Xether * Pether) / Pbenzoic acid

Substituting the given values:
Xbenzoic acid = (342 - 0.760 * 400) / 60 = 0.145

Therefore, the mole fraction of benzoic acid in the solution is 0.145, which is choice C.

Question 12

Barbiturates are synthetic drugs used as sedatives and hypnotics.Barbital ( = 184.2 g/mol)is one of the simplest of these drugs.What is the boiling point of a solution prepared by dissolving 42.5 g of barbital in 825 g of acetic acid? K_b = 3.07°C/m,boiling point of pure acetic acid = 117.9°C A)117.0°C B)117.7°C C)118.1°C D)118.8°C E)>120°C

Accepted Answer

The answer of Barbiturates are synthetic drugs used as sedatives...

Question 13

Which of the following aqueous liquids will have the lowest freezing point? A)0.5 m C₁₂H₂₂O₁₁ (sucrose) B)0.5 m Ca(NO₃)₂ C)0.5 m NiSO₄ D)0.5 m Li₃PO₄ E)pure water

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Question 14

The density of pure water at 25°C is 0.997 g/mL.Considering water as being both solvent and solute,calculate its molarity.

Accepted Answer

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Question 15

A 50.0 % (w/w)solution of sulfuric acid (H₂SO₄)in water has a density of 1.395 g/mL.What is its molarity?

Accepted Answer

The answer of A 50.0 % (w/w)solution of sulfuric acid...

Question 16

A 0.100 m K₂SO₄ solution has a freezing point of -0.43°C.What is the van't Hoff factor for this solution? K_f = 1.86°C/m A)0.77 B)1.0 C)2.3 D)3.0 E)>3.0

Accepted Answer

The van't Hoff factor (i) can be calculated using the formula:
ΔTf = iKf*m
where ΔTf is the freezing-point depression, Kf is the freezing-point depression constant for the solvent, and m is the molality of the solution.
By rearranging the formula we get:
i = ΔTf / (Kf * m)

Substituting the given values:
ΔTf = (freezing point of pure solvent - freezing point of solution) = (0°C - (-0.43°C)) = 0.43°C
Kf for water = 1.86°C/m
m = 0.100 mol/kg

i = 0.43°C / (1.86°C/m * 0.100 mol/kg) = 2.31
So the van't Hoff factor is 2.3, which is closest to option C.

Question 17

Benzaldehyde ( = 106.1 g/mol),also known as oil of almonds,is used in the manufacture of dyes and perfumes and in flavorings.What would be the freezing point of a solution prepared by dissolving 75.00 g of benzaldehyde in 850.0 g of ethanol? K_f = 1.99°C/m,freezing point of pure ethanol = -117.3°C. A)-117.5°C B)-118.7°C C)-119.0°C D)-120.6°C E)< -121°C

Accepted Answer

The answer of Benzaldehyde ( 
= 106.1 g/mol),also known as...

Question 18

Calculate the vapor pressure of a solution prepared by dissolving 0.500 mol of a non-volatile solute in 275 g of hexane ( = 86.18 g/mol)at 49.6°C.P°_hexane = 400.0 torr at 49.6°C. A)54 torr B)154 torr C)246 torr D)346 torr E)400.torr

Accepted Answer

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Question 19

A 0.100 m MgSO₄ solution has a freezing point of -0.23°C.What is the van't Hoff factor for this solution? K_f = 1.86°C/m A)0.62 B)1.0 C)1.2 D)2.0 E)4.0

Accepted Answer

The freezing point depression equation is:
ΔTf = Kf * molality * i

Where ΔTf is the change in freezing point, Kf is the freezing point depression constant, molality is the concentration expressed in moles of solute per kilogram of solvent, and i is the van't Hoff factor.

Given that ΔTf = -0.23°C, Kf = 1.86°C/m, and molality = 0.100 mol/kg, we can solve for i as follows:

-0.23°C = (1.86°C/m) * (0.100 mol/kg) * i
i = -0.23°C / [(1.86°C/m) * (0.100 mol/kg)] = 1.23
i ≈ 1.2

Therefore, the van't Hoff factor for this solution is 1.2, and the best choice is (C).

Question 20

Carbon tetrachloride,once widely used in fire extinguishers and as a dry cleaning fluid,has been found to cause liver damage to those exposed to its vapors over long periods of time.What is the boiling point of a solution prepared by dissolving 375 g of sulfur (S₈, = 256.5g/mol)in 1250 g of CCl₄? K_b = 5.05°C/m,boiling point of pure CCl₄ = 76.7°C? A)70.8°C B)75.2°C C)78.2°C D)82.6°C E)>85°C

Accepted Answer

The answer of Carbon tetrachloride,once widely used in fire extinguishers...

Quiz 13: The Properties of Solutions

Cinnamaldehyde ( = 132.15 g/mol) is used as a flavoring agent.What mass of cinnamaldehyde must be added to 175 g of ethanol to give a solution whose boiling point is 82.7°C? K_b = 1.22°C/m,boiling point of pure ethanol = 78.5°C

Lysine is an amino acid that is an essential part of nutrition but which is not synthesized by the human body.What is the molar mass of lysine if 750.0 mL of a solution containing 8.60 g of lysine has an osmotic pressure of 1.918 atm? T = 25.0°C

Human blood has a molar concentration of solutes of 0.30 M.What is the osmotic pressure of blood at 25°C?

Safrole is used as a topical antiseptic.Calculate the vapor pressure of a solution prepared by dissolving 0.75 mol of safrole in 950 g of ethanol ( = 46.07 g/mol) .P°_ethanol = 50.0 torr at 25°C.

Determine the freezing point of a solution which contains 0.31 mol of sucrose in 175 g of water.K_f = 1.86°C/m

Two aqueous solutions are prepared: 2.0 m Cu(NO₃) ₂ and 2.0 m NaBr.Which of the following statements is true?

Calculate the freezing point of a solution made by dissolving 3.50 g of potassium chloride ( = 74.55 g/mol) in 100.0 g of water.Assume ideal behavior for the solution;K_f = 1.86°C/m.

Which of the following aqueous solutions will have the lowest osmotic pressure?

Hexachlorophene is used as a disinfectant in germicidal soaps.What mass of hexachlorophene ( = 406.9 g/mol) must be added to 125 g of chloroform to give a solution with a boiling point of 62.60°C? K_b = 3.63°C/m,boiling point of pure chloroform = 61.70°C

Dimethylglyoxime,DMG,is an organic compound used to test for aqueous nickel(II) ions.A solution prepared by dissolving 65.0 g of DMG in 375 g of ethanol boils at 80.3°C.What is the molar mass of DMG? K_b = 1.22°C/m,boiling point of pure ethanol = 78.5°C

Diethyl ether has a vapor pressure of 400.0 torr at 18°C.When a sample of benzoic acid is dissolved in ether,the vapor pressure of the solution is 342 torr.What is the mole fraction of benzoic acid in the solution?

Barbiturates are synthetic drugs used as sedatives and hypnotics.Barbital ( = 184.2 g/mol) is one of the simplest of these drugs.What is the boiling point of a solution prepared by dissolving 42.5 g of barbital in 825 g of acetic acid? K_b = 3.07°C/m,boiling point of pure acetic acid = 117.9°C

Which of the following aqueous liquids will have the lowest freezing point?

The density of pure water at 25°C is 0.997 g/mL.Considering water as being both solvent and solute,calculate its molarity.

A 50.0 % (w/w)solution of sulfuric acid (H₂SO₄)in water has a density of 1.395 g/mL.What is its molarity?

A 0.100 m K₂SO₄ solution has a freezing point of -0.43°C.What is the van't Hoff factor for this solution? K_f = 1.86°C/m

Calculate the vapor pressure of a solution prepared by dissolving 0.500 mol of a non-volatile solute in 275 g of hexane ( = 86.18 g/mol) at 49.6°C.P°_hexane = 400.0 torr at 49.6°C.

A 0.100 m MgSO₄ solution has a freezing point of -0.23°C.What is the van't Hoff factor for this solution? K_f = 1.86°C/m

Quiz 13: The Properties of Solutions

Cinnamaldehyde ( = 132.15 g/mol) is used as a flavoring agent.What mass of cinnamaldehyde must be added to 175 g of ethanol to give a solution whose boiling point is 82.7°C? Kb = 1.22°C/m,boiling point of pure ethanol = 78.5°C

Lysine is an amino acid that is an essential part of nutrition but which is not synthesized by the human body.What is the molar mass of lysine if 750.0 mL of a solution containing 8.60 g of lysine has an osmotic pressure of 1.918 atm? T = 25.0°C

Human blood has a molar concentration of solutes of 0.30 M.What is the osmotic pressure of blood at 25°C?

Safrole is used as a topical antiseptic.Calculate the vapor pressure of a solution prepared by dissolving 0.75 mol of safrole in 950 g of ethanol ( = 46.07 g/mol) .P°ethanol = 50.0 torr at 25°C.

Determine the freezing point of a solution which contains 0.31 mol of sucrose in 175 g of water.Kf = 1.86°C/m

Two aqueous solutions are prepared: 2.0 m Cu(NO3) 2 and 2.0 m NaBr.Which of the following statements is true?

Calculate the freezing point of a solution made by dissolving 3.50 g of potassium chloride ( = 74.55 g/mol) in 100.0 g of water.Assume ideal behavior for the solution;Kf = 1.86°C/m.

Which of the following aqueous solutions will have the lowest osmotic pressure?

Hexachlorophene is used as a disinfectant in germicidal soaps.What mass of hexachlorophene ( = 406.9 g/mol) must be added to 125 g of chloroform to give a solution with a boiling point of 62.60°C? Kb = 3.63°C/m,boiling point of pure chloroform = 61.70°C

Dimethylglyoxime,DMG,is an organic compound used to test for aqueous nickel(II) ions.A solution prepared by dissolving 65.0 g of DMG in 375 g of ethanol boils at 80.3°C.What is the molar mass of DMG? Kb = 1.22°C/m,boiling point of pure ethanol = 78.5°C

Diethyl ether has a vapor pressure of 400.0 torr at 18°C.When a sample of benzoic acid is dissolved in ether,the vapor pressure of the solution is 342 torr.What is the mole fraction of benzoic acid in the solution?

Barbiturates are synthetic drugs used as sedatives and hypnotics.Barbital ( = 184.2 g/mol) is one of the simplest of these drugs.What is the boiling point of a solution prepared by dissolving 42.5 g of barbital in 825 g of acetic acid? Kb = 3.07°C/m,boiling point of pure acetic acid = 117.9°C

Which of the following aqueous liquids will have the lowest freezing point?

The density of pure water at 25°C is 0.997 g/mL.Considering water as being both solvent and solute,calculate its molarity.

A 50.0 % (w/w)solution of sulfuric acid (H2SO4)in water has a density of 1.395 g/mL.What is its molarity?

A 0.100 m K2SO4 solution has a freezing point of -0.43°C.What is the van't Hoff factor for this solution? Kf = 1.86°C/m

Calculate the vapor pressure of a solution prepared by dissolving 0.500 mol of a non-volatile solute in 275 g of hexane ( = 86.18 g/mol) at 49.6°C.P°hexane = 400.0 torr at 49.6°C.

A 0.100 m MgSO4 solution has a freezing point of -0.23°C.What is the van't Hoff factor for this solution? Kf = 1.86°C/m

Cinnamaldehyde ( = 132.15 g/mol) is used as a flavoring agent.What mass of cinnamaldehyde must be added to 175 g of ethanol to give a solution whose boiling point is 82.7°C? K_b = 1.22°C/m,boiling point of pure ethanol = 78.5°C

Safrole is used as a topical antiseptic.Calculate the vapor pressure of a solution prepared by dissolving 0.75 mol of safrole in 950 g of ethanol ( = 46.07 g/mol) .P°_ethanol = 50.0 torr at 25°C.

Determine the freezing point of a solution which contains 0.31 mol of sucrose in 175 g of water.K_f = 1.86°C/m

Two aqueous solutions are prepared: 2.0 m Cu(NO₃) ₂ and 2.0 m NaBr.Which of the following statements is true?

Calculate the freezing point of a solution made by dissolving 3.50 g of potassium chloride ( = 74.55 g/mol) in 100.0 g of water.Assume ideal behavior for the solution;K_f = 1.86°C/m.

Hexachlorophene is used as a disinfectant in germicidal soaps.What mass of hexachlorophene ( = 406.9 g/mol) must be added to 125 g of chloroform to give a solution with a boiling point of 62.60°C? K_b = 3.63°C/m,boiling point of pure chloroform = 61.70°C

Dimethylglyoxime,DMG,is an organic compound used to test for aqueous nickel(II) ions.A solution prepared by dissolving 65.0 g of DMG in 375 g of ethanol boils at 80.3°C.What is the molar mass of DMG? K_b = 1.22°C/m,boiling point of pure ethanol = 78.5°C

Barbiturates are synthetic drugs used as sedatives and hypnotics.Barbital ( = 184.2 g/mol) is one of the simplest of these drugs.What is the boiling point of a solution prepared by dissolving 42.5 g of barbital in 825 g of acetic acid? K_b = 3.07°C/m,boiling point of pure acetic acid = 117.9°C

A 50.0 % (w/w)solution of sulfuric acid (H₂SO₄)in water has a density of 1.395 g/mL.What is its molarity?

A 0.100 m K₂SO₄ solution has a freezing point of -0.43°C.What is the van't Hoff factor for this solution? K_f = 1.86°C/m

Calculate the vapor pressure of a solution prepared by dissolving 0.500 mol of a non-volatile solute in 275 g of hexane ( = 86.18 g/mol) at 49.6°C.P°_hexane = 400.0 torr at 49.6°C.

A 0.100 m MgSO₄ solution has a freezing point of -0.23°C.What is the van't Hoff factor for this solution? K_f = 1.86°C/m