If the cyclohexane is initially contaminated with a soluble non-reactive, non-volatile substance, will the change in freezing point, delta Tf, be
a. Higher
b. Lower
c. The same as the uncontaminated cyclohexane?
There will be no change hence delta Tf will be the same as the uncontaminated cyclohexane?
If I understand the question I agree with your answer.
When a soluble non-reactive, non-volatile substance is added to a solvent, such as cyclohexane, the change in freezing point, ΔTf, will be lower than the uncontaminated cyclohexane.
Adding a non-volatile solute to a solvent will result in a decrease in the freezing point of the solution compared to the pure solvent. This is due to the solute particles interfering with the formation of the solvent's crystal lattice structure, making it more difficult for the solution to solidify.
Therefore, the correct answer is b. Lower.
To determine whether the change in freezing point, delta Tf, will be higher, lower, or the same as the uncontaminated cyclohexane, we need to consider how the presence of a soluble non-reactive, non-volatile substance affects the freezing point depression.
When a substance is dissolved in a solvent, such as cyclohexane, it lowers the freezing point of the solvent. This is due to the fact that the solute particles disrupt the regular arrangement of solvent particles, making it more difficult for the solvent to freeze.
In the case of a soluble non-reactive, non-volatile substance contaminating the cyclohexane, it means that the substance does not react with the cyclohexane and does not vaporize at the boiling point of cyclohexane. This implies that the substance will not affect the vapor pressure of the solution, which is a key factor in determining the change in freezing point.
Since the contaminating substance is non-volatile and does not affect the vapor pressure, the presence of the contaminant will not cause any additional freezing point depression. Therefore, the change in freezing point, delta Tf, will be the same as the uncontaminated cyclohexane. Hence, the correct answer is c. The same as the uncontaminated cyclohexane.