I need help on my lab. I think I have all the data and steps right, but my results aren't making sense:

Feezing point of water: -0.58 C
Freezing point of Unknown: -0.93 C
Freezing point depressions: 0.34 C

Mass of unknown: 1.045 g, mass of solvent (water): 19 ml, Water=1.86 C/m, Tf=Kfm

0.34 = 1.86*m
m=0.183
0.183=moles of solute/.019 kg
moles of solute = .0035
molar mass = 1.045g/.0035
= 298.57 g/mol

However this molar mass doesn't match any of the options I have for what the unknown compounds might be. Can you see anything I might have made a mistake on?

1. Do you know this was a non-ionic compound?

2. -0.58-(-0.93) = 0.35
3. Using the 0.35 for the depression, I would not round to 0.0035 since the use of significant figures is not consistent.
4. What are the options for the molar mass?
5. What are the options for the compounds?

Based on the information you provided, it seems like you have followed the correct steps to determine the molar mass of your unknown compound. However, if the molar mass you have calculated does not match any of the options for the unknown compounds, there might be a mistake in your calculations or the data you have collected.

Here's a breakdown of the steps you took and what to check:

1. Freezing point depressions: You correctly calculated the freezing point depression as 0.34 °C.

2. Determining the molality (m) of the solution:
You used the formula delta Tf = Kf * m, where delta Tf is the freezing point depression, Kf is the molal freezing point constant for water (1.86 °C/m), and m is the molality of the solution.
You correctly rearranged the formula to solve for m: m = delta Tf / Kf. Plugging in the values, you obtained 0.183 mol/kg.

3. Calculating moles of solute:
You divided the mass of the solute (1.045 g) by the mass of the solvent (19 mL), which should be converted to kilograms. However, it seems like there might be a discrepancy in the units.
Please verify if the mass of the solvent is indeed given in milliliters (mL) and if it is correct. If the mass of the solvent is actually given in grams (g), you should convert it to kilograms (kg) before proceeding with the calculations.

4. Calculating molar mass:
You divided the mass of the solute (1.045 g) by the moles of solute (0.0035 mol) to obtain a molar mass of 298.57 g/mol. Double-check your calculations to ensure they are accurate.

If you have confirmed that the given data and calculations are correct, it is possible that the unknown compound might not match the options you have. In that case, you should consult with your instructor or refer to additional resources for further assistance.

Remember, it's always important to double-check your calculations, units, and data to ensure accuracy in your lab work.