A 1.90-g sample of a large biomolecule was dissolved in 25.0 g of carbon tetrachloride. The boiling point of this solution was determined to be 77.85°C. Calculate the molar mass of the biomolecule. For carbon tetrachloride, the boiling point constant is 5.03°C · kg/mol, and the boiling point of pure carbon tetrachloride is 76.50°C.

delta T = Kb*m

delta T = 77.85-76.50
Kb = 5.03
Solve for m
m = mols/kg solvent. You know m and kg solvent, solve for mols.
mol = grams/molar mass. You know mol and grams, solve for molar mass.

To calculate the molar mass of the biomolecule, we can use the formula for the boiling point elevation:

ΔT = K_b * m

where ΔT is the boiling point elevation, K_b is the boiling point constant, and m is the molality of the solute (in this case, the biomolecule).

First, let's calculate the molality of the biomolecule by dividing its mass by the mass of the solvent:

m = (1.90 g biomolecule) / (25.0 g CCl4) = 0.076 mol/kg

Next, we can use the boiling point elevation formula to find ΔT:

ΔT = (77.85°C - 76.50°C)

Now, we can substitute the values into the formula and solve for the molar mass (M) of the biomolecule:

ΔT = K_b * m
ΔT = 5.03°C · kg/mol * (0.076 mol/kg)
(77.85°C - 76.50°C) = 5.03°C · kg/mol * (0.076 mol/kg)
1.35°C = 0.3828 mol · L/mol

Finally, to find the molar mass, we can rearrange the formula:

M = (molar mass of the biomolecule) / (molality of the biomolecule)
M = (1.35°C) / (0.3828 mol · L/mol)
M ≈ 3.52 g/mol

Therefore, the molar mass of the biomolecule is approximately 3.52 g/mol.