The boiling point of an aqueous solution is 102.16 C. What is the freezing point?
Dr. Bob, If you happen to answer this question, I was the one that a question earlier about how to know what Kf constant to use [water vs benzene?] and i didn't notice that it was given in the problem but I was wondering how you know which K constant to use in problems like these when they don't tell you what the aqueous solution is. Please help! Thank you so much ahead of time if this question is addressed!
They MUST tell you in the problem. If they use the word aqueous you know it is water. Otherwise they will say in benzene, naphthalene, etc. (Aqueous means a solution in water).
delta T = (102.16-100) = Kb*m
Solve for m
Then for freezing,
delta T = Kf*m
You know Kf and m, solve for delta T and subtract from O C.
OHHHHHHHHHHHHHHHHHHHHHHHHHH....... THANKS DR BOB!!!! always so helpful
To determine the freezing point of an aqueous solution, we can use the formula:
ΔTf = Kf * m
where ΔTf represents the change in freezing point, Kf is the cryoscopic constant (also known as the molal freezing point depression constant), and m is the molality of the solute in the solution.
In this case, we are given the boiling point of the solution, but not the specific identity of the solute. Unfortunately, we cannot directly calculate the freezing point from the boiling point without additional information or assumptions.
Different solutes have different molal freezing point depression constants. For example, the Kf value for water is 1.86 °C·kg/mol, while benzene has a Kf value of 5.12 °C·kg/mol. These values represent the decrease in freezing point per mole of solute dissolved in 1 kg of solvent.
To determine the freezing point of an aqueous solution, we need to know the specific identity of the solute and its molality. Without this information, it would be impossible to calculate the freezing point accurately.
If the problem does not provide the specific identity of the solute or its molality, it may be a sign that the question is incomplete or that additional information is required to solve it. In such cases, it is best to seek clarification or additional data to proceed with the calculation.