Cyclohexane has a freezing point of 6.6 degree Celsius and a K(f) of 20.0 degree Celsius/m. 1.50g of an unknown solute is dissolved wth 18.0g of cyclohexane. The freezing point of the solution was 1.3 degree Celsius Using this iInformation assuming the solute doesn't dissociate, calculate the:

a) The molality of this solution;

b) Moles of solute present;

c) Molar mass of the solute.

T = 6.6 - 1.3 = 5.3

5.3 = m x 20.0

molality = 5.3 / 20.0=0.265

moles solute = 0.265 x 0.0180 Kg =0.00477

molar mass solute = 1.50 / 0.00477=314.5 g/mol.

I think the answers may be right. I just want to make sure.

Wrong

Your calculations are correct. Here's a step-by-step breakdown of the calculations for each part:

a) To find the molality of the solution, use the formula:

molality = (change in freezing point) / (K(f))

Given that the change in freezing point is 5.3 degrees Celsius and the K(f) is 20.0 degrees Celsius/m, plug in these values:
molality = 5.3 / 20.0 = 0.265

b) Next, to find the moles of solute present, use the formula:

moles = molality x (mass of solvent in kg)

Given that the mass of the solvent (cyclohexane) is 18.0g (0.0180 kg) and the molality is 0.265, plug in these values:
moles = 0.265 x 0.0180 = 0.00477 moles

c) Lastly, to find the molar mass of the solute, use the formula:

molar mass = (mass of solute) / (moles of solute)

Given that the mass of the solute is 1.50g and the moles of solute is 0.00477, plug in these values:
molar mass = 1.50 / 0.00477 = 314.5 g/mol

So, your answers are indeed correct:
a) The molality of this solution is 0.265 mol/kg.
b) The moles of solute present are 0.00477 moles.
c) The molar mass of the solute is 314.5 g/mol.

Your calculations are correct! Well done!

To explain the process:

a) To calculate the molality of the solution, you first need to find the change in temperature. This is done by subtracting the freezing point of the solution (1.3°C) from the freezing point of the pure solvent (6.6°C), which gives you a value of 5.3°C.

Next, you use the equation ΔT = K(f) × m, where ΔT is the change in temperature, K(f) is the freezing point depression constant, and m is the molality of the solution. Rearranging the formula, you have m = ΔT / K(f). Substituting the given values into the equation, you get m = 5.3°C / 20.0°C/m = 0.265 mol/kg.

b) To find the moles of solute present, you multiply the molality of the solution by the mass of the solvent used. Convert the mass of the solvent from grams to kilograms by dividing by 1000: 18.0g / 1000 = 0.0180 kg.

Then, the equation moles = molality × kg of solvent gives you the moles of solute present: moles = 0.265 mol/kg × 0.0180 kg = 0.00477 moles.

c) Finally, to calculate the molar mass of the solute, divide the mass of the solute by the moles of solute. Given that the mass of the solute is 1.50g and the moles of solute is 0.00477 moles, you have molar mass = 1.50g / 0.00477 moles = 314.5 g/mol.

So, your answers for all three parts (a, b, c) are correct.

Looks ok to me.