what is the freezing point depression of water, benzene, acetic acid, ethanol and clyclohexane?
Those constants usually are quite accessible. If they are not in your text/notes, you can google " table freezing point depression constants"
To find the freezing point depression of a substance, we need to know its freezing point and the molal freezing point depression constant (Kf) of the solvent.
The freezing point depression (ΔTf) can be calculated using the equation:
ΔTf = Kf × m
Where:
ΔTf = freezing point depression (in degrees Celsius)
Kf = molal freezing point depression constant (in degrees Celsius/mole)
m = molality of the solute (in moles of solute per kilogram of solvent)
Here are the freezing point depressions for the given substances:
1. Water (H2O):
The freezing point of pure water is 0 degrees Celsius, and the molal freezing point depression constant for water is approximately 1.86 degrees Celsius/mole.
(Note: The molal freezing point depression constant for water is approximately the same as the boiling point elevation constant, Kb, for water.)
2. Benzene (C6H6):
The freezing point of pure benzene is 5.5 degrees Celsius, and the molal freezing point depression constant for benzene is approximately 5.12 degrees Celsius/mole.
3. Acetic acid (CH3COOH):
The freezing point of pure acetic acid is 16.6 degrees Celsius, and the molal freezing point depression constant for acetic acid is approximately 3.90 degrees Celsius/mole.
4. Ethanol (C2H5OH):
The freezing point of pure ethanol is -114 degrees Celsius, and the molal freezing point depression constant for ethanol is approximately 1.99 degrees Celsius/mole.
5. Cyclohexane (C6H12):
The freezing point of pure cyclohexane is 6.6 degrees Celsius, and the molal freezing point depression constant for cyclohexane is approximately 20.0 degrees Celsius/mole.
Please note that the given values are approximate and can vary slightly depending on the source and conditions. To obtain more accurate results, it is recommended to refer to reliable scientific literature or databases.