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The freezing point of ethanol CH3CH₂OH is -117.30°C at 1 atmosphere. A nonvolatile, nonelectrolyte that dissolves in ethanol is chlorophyll. If 13.92 grams of chlorophyll, C55H72MgN4O5 (893.5 g/mol), are dissolved in 186.9 grams of ethanol ... The molality of the solution is The freezing point of the solution is m. °C.

The freezing point of ethanol CH3CH₂OH is -117.30°C at 1 atmosphere. A nonvolatile, nonelectrolyte that dissolves in ethanol is chlorophyll. If 13.92 grams of chlorophyll, C55H72MgN4O5 (893.5 g/mol), are dissolved in 186.9 grams of ethanol ... The molality of the solution is The freezing point of the solution is m. °C.

Chemistry
Chemistry
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ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
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Boiling Point Elevation/Freezing Point Depression AT = m K Where: AT = T(solution) - T(pure solvent) * m = (# moles solute / Kg solvent) Kb = boiling point elevation constant. Kf = freezing point depression constant. K₁ and Kf depend only on the SOLVENT. Below are some common values. Use these values for the calculations that follow. Solvent Water Ethanol Chloroform Benzene Diethyl ether Formula H₂O CH3CH₂OH CHCI 3 C6H6 CH3CH₂CH₂CH3 Kb (°C/ m) Kf (°C / m) 0.512 1.22 3.67 2.53 2.02 -1.86 -1.99 -5.12 *Please note that AT as defined above will be a negative number for freezing point depression. Therefore, Kf must also be given as a negative number.
Transcribed Image Text:Boiling Point Elevation/Freezing Point Depression AT = m K Where: AT = T(solution) - T(pure solvent) * m = (# moles solute / Kg solvent) Kb = boiling point elevation constant. Kf = freezing point depression constant. K₁ and Kf depend only on the SOLVENT. Below are some common values. Use these values for the calculations that follow. Solvent Water Ethanol Chloroform Benzene Diethyl ether Formula H₂O CH3CH₂OH CHCI 3 C6H6 CH3CH₂CH₂CH3 Kb (°C/ m) Kf (°C / m) 0.512 1.22 3.67 2.53 2.02 -1.86 -1.99 -5.12 *Please note that AT as defined above will be a negative number for freezing point depression. Therefore, Kf must also be given as a negative number.
The freezing point of ethanol CH3CH₂OH is -117.30°C at 1 atmosphere. A nonvolatile, nonelectrolyte that dissolves in ethanol is chlorophyll. If 13.92 grams of chlorophyll, C55H72MgN405 (893.5 g/mol), are dissolved in 186.9 grams of ethanol ….. The molality of the solution is The freezing point of the solution is m. °C.
Transcribed Image Text:The freezing point of ethanol CH3CH₂OH is -117.30°C at 1 atmosphere. A nonvolatile, nonelectrolyte that dissolves in ethanol is chlorophyll. If 13.92 grams of chlorophyll, C55H72MgN405 (893.5 g/mol), are dissolved in 186.9 grams of ethanol ….. The molality of the solution is The freezing point of the solution is m. °C.
Expert Solution
Step 1

Given mass of chlorophyll = 13.92 g 

Molar mass of chlorophyll = 893.5 g/mol 

Mass of ethanol = 186.9 g = 0.1869 Kg 

(1 kg = 1000g )

Freezing point of ethanol (solvent) = -117.30 °C 

The solute is chlorophyll and the solvent is ethanol . 

Formula : 

Molality = moles of solute ÷ mass of solvent (in kg) 

Freezing point of solution = freezing point of ethanol - delta T 

where delta T is freezing point depression  

And delta T is determined by : 

delta T = i × Kf × m 

i = vant hoff factor (for chlorophyll it's value is one as it's  non volatile) 

Kf  = freezing point depression constant of ethanol 

m = Molality of solution 

 

 

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