The solute, in order for it to exert any change on colligative properties, must fulfill two conditions. First, it must not contribute to the vapor pressure of the solution, and second, it must remain suspended in the solution even during phase changes. Because the solvent is no longer pure with the addition of solutes, we can say that the chemical potential of the solvent is lower.
Chemical potential is the molar Gibb's energy that one mole of solvent is able to contribute to a mixture. The higher the chemical potential of a solvent is, the more it is able to drive the reaction forward. Consequently, solvents with higher chemical potentials will also have higher vapor pressures. The boiling point is reached when the chemical potential of the pure solvent, a liquid, reaches that of the chemical potential of pure vapor. Because of the decrease in the chemical potential of mixed solvents and solutes, we observe this intersection at higher temperatures.
In other words, the boiling point of the impure solvent will be at a higher temperature than that of the pure liquid solvent. Thus, boiling point elevation occurs with a temperature increase that is quantified using.
Freezing point is reached when the chemical potential of the pure liquid solvent reaches that of the pure solid solvent. Again, since we are dealing with mixtures with decreased chemical potential, we expect the freezing point to change. Unlike the boiling point, the chemical potential of the impure solvent requires a colder temperature for it to reach the chemical potential of the pure solid solvent.
Therefore, a freezing point depression is observed. What is the molar mass of the compound? First we must compute the molality of the benzene solution, which will allow us to find the number of moles of solute dissolved. The freezing point depression is especially vital to aquatic life. After converting the gram amounts to moles we find that the mole fraction of the solvent ethanol is 0. Therefore, the vapor pressure of the solvent is Problem : What is the freezing point of a solution of The molal freezing point constant, K f , for water is 1.
The concentration of the solution is 1. Therefore, the change in the freezing point of the water is The freezing point of the solution is, therefore, How do you calculate freezing point depression? How can freezing point depression determine purity? How does the nature of the solute affect boiling point? How do colligative properties affect freezing point? What colligative property causes ice to melt?
Why do colligative properties depend on the number of particles? How do ionic solutes affect the boiling point?
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