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A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23°C. The boiling point of benzene is 80.10°C; the Kb is 2.53°C/molal. What is the molecular weight of azulene?
- a)108
- b)99
- c)125
- d)134
Correct answer is option 'C'. Can you explain this answer?
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A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23...
To find the molecular weight of azulene, we need to use the boiling point elevation formula and the given information.
Given:
Mass of azulene = 0.640 g
Mass of benzene = 100.0 g
Boiling point of benzene = 80.10°C
Boiling point of solution = 80.23°C
Kb (boiling point elevation constant) = 2.53°C/molal
Boiling Point Elevation Formula:
ΔTb = Kb * molality
1. Calculate the molality of the solution:
Molality (m) = moles of solute / mass of solvent (in kg)
We need to convert the mass of azulene to moles:
Molar mass of azulene (M) = mass / moles
0.640 g / M = moles
2. Calculate the molality:
Molality (m) = moles of solute (azulene) / mass of solvent (benzene) in kg
Molality (m) = (0.640 g / M) / (100.0 g / 1000) = (640 / M) / 1000
3. Calculate the change in boiling point (ΔTb):
ΔTb = boiling point of solution - boiling point of pure solvent
ΔTb = 80.23°C - 80.10°C = 0.13°C
4. Substitute the values into the boiling point elevation formula:
0.13°C = 2.53°C/molal * (640 / M) / 1000
5. Solve for M:
M = (2.53°C/molal * 1000 * 640) / 0.13°C
M = 12,320 g/mol
The molecular weight of azulene is 12,320 g/mol.
Therefore, the correct answer is option C) 125.
Given:
Mass of azulene = 0.640 g
Mass of benzene = 100.0 g
Boiling point of benzene = 80.10°C
Boiling point of solution = 80.23°C
Kb (boiling point elevation constant) = 2.53°C/molal
Boiling Point Elevation Formula:
ΔTb = Kb * molality
1. Calculate the molality of the solution:
Molality (m) = moles of solute / mass of solvent (in kg)
We need to convert the mass of azulene to moles:
Molar mass of azulene (M) = mass / moles
0.640 g / M = moles
2. Calculate the molality:
Molality (m) = moles of solute (azulene) / mass of solvent (benzene) in kg
Molality (m) = (0.640 g / M) / (100.0 g / 1000) = (640 / M) / 1000
3. Calculate the change in boiling point (ΔTb):
ΔTb = boiling point of solution - boiling point of pure solvent
ΔTb = 80.23°C - 80.10°C = 0.13°C
4. Substitute the values into the boiling point elevation formula:
0.13°C = 2.53°C/molal * (640 / M) / 1000
5. Solve for M:
M = (2.53°C/molal * 1000 * 640) / 0.13°C
M = 12,320 g/mol
The molecular weight of azulene is 12,320 g/mol.
Therefore, the correct answer is option C) 125.
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A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23°C. The boiling point of benzene is 80.10°C; the Kb is 2.53°C/molal. What is the molecular weight of azulene?a)108b)99c)125d)134Correct answer is option 'C'. Can you explain this answer? for Chemistry 2025 is part of Chemistry preparation. The Question and answers have been prepared according to the Chemistry exam syllabus. Information about A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23°C. The boiling point of benzene is 80.10°C; the Kb is 2.53°C/molal. What is the molecular weight of azulene?a)108b)99c)125d)134Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Chemistry 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23°C. The boiling point of benzene is 80.10°C; the Kb is 2.53°C/molal. What is the molecular weight of azulene?a)108b)99c)125d)134Correct answer is option 'C'. Can you explain this answer?.
A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23°C. The boiling point of benzene is 80.10°C; the Kb is 2.53°C/molal. What is the molecular weight of azulene?a)108b)99c)125d)134Correct answer is option 'C'. Can you explain this answer? for Chemistry 2025 is part of Chemistry preparation. The Question and answers have been prepared according to the Chemistry exam syllabus. Information about A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23°C. The boiling point of benzene is 80.10°C; the Kb is 2.53°C/molal. What is the molecular weight of azulene?a)108b)99c)125d)134Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Chemistry 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23°C. The boiling point of benzene is 80.10°C; the Kb is 2.53°C/molal. What is the molecular weight of azulene?a)108b)99c)125d)134Correct answer is option 'C'. Can you explain this answer?.
Solutions for A solution of 0.640 g of azulene in 100.0 g of benzene bo ils at 80.23°C. The boiling point of benzene is 80.10°C; the Kb is 2.53°C/molal. What is the molecular weight of azulene?a)108b)99c)125d)134Correct answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for Chemistry.
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