OK, you have molality = m
m = mol/kg solvent. You have m and kg solvent, substitute and solve for mol.
Then mol = g/molar mass. You have mol and grams, solve for molar mass.
Tf (acetic acid) = 16.1°C
Tf (with 3.00g of solute in 10.00mL of acetic acid) = - 2.5°C
Use the data to calculate the molecular mass of the solute (Acetic acid: Kf = 3.9°C•kg/mol; D = 1.05 g/mL)
After finding molality I was completely stuck on what to do next..
3 answers
Could you please explain the steps? I am still unsure about what I am doing...
The steps are there. Just follow my instructions What's confusing?
.You say you have m. Then m = mols/kg solvent. The problem tells you kg solvent is 10 mL acetic acid. density of the acid iis 1.05 g/mL so
mass = density x volume = 1.05 g/mL x 10 mL = 10.5 grams or 0.0105 kg.
m = mols/0.0105 kg and mols = m x 0.0105 = ? mols. Plug in your m to find mols. Then mols = grams/molar mass. You have just calculated mols. The problem tells you grams = 3.00. Solve for molar mass.
.You say you have m. Then m = mols/kg solvent. The problem tells you kg solvent is 10 mL acetic acid. density of the acid iis 1.05 g/mL so
mass = density x volume = 1.05 g/mL x 10 mL = 10.5 grams or 0.0105 kg.
m = mols/0.0105 kg and mols = m x 0.0105 = ? mols. Plug in your m to find mols. Then mols = grams/molar mass. You have just calculated mols. The problem tells you grams = 3.00. Solve for molar mass.