What is the molar mass of toluene if 0.85 g of toluene depresses the freezing point of 100 g of benzene by 0.47 degrees celsius? Kf= 5.12 C/m

delta T = kf*m

Substitute and solve for m = molality. You know delta T and Kf.

m = mols/kg solvent You know kg solvent and m.

mols = grams/molar mass. Substitute and solve for molar mass. Yo know grams and mols.

whats molar mass for toluene

C7H8 is toluene.

92.14 is molar mass.

To find the molar mass of toluene, we can use the equation for freezing point depression:

ΔT = Kf * m * i

Where:
ΔT is the change in freezing point in degrees Celsius.
Kf is the molal freezing point depression constant for the solvent.
m is the molality of the solute (in mol solute / kg solvent).
i is the van't Hoff factor, which represents the number of particles into which the solute dissociates.

In this case, we are given:
ΔT = -0.47 °C (negative sign indicates a depression in freezing point)
Kf = 5.12 °C/m
m = ? (to be determined)
i = 1 (since toluene does not dissociate into ions)

First, we need to calculate the molality (m) of the toluene solution. To do this, we use the following formula:

molality (m) = moles of solute / mass of solvent (in kg)

In this case, we know that the mass of the toluene solute is 0.85 g (given). To obtain the mass of the benzene solvent, we need to convert the given amount from grams to kilograms. Since 1 kg = 1000 g, 100 g of benzene is equivalent to 100/1000 = 0.1 kg.

Now we can substitute the values into the formula and solve for m:

m = (0.85 g / molar mass of toluene) / 0.1 kg

Rearranging the equation:

molar mass of toluene = (0.85 g / (m * 0.1 kg))

Finally, substitute the molality value (m) and solve for the molar mass of toluene.

Note: To find the accurate molar mass of toluene, we also need to account for the number of significant figures in the input values. Please provide the accurate values if available.