I want to say that you aren't helping very much. What is the freezing point constant? What is the freezing point for benzene. You need to look up those values. You may use your text, the web, or your notes.
mass = volume x density so mass benzene is
mass = 25.00 mL x 0.879 g/mL = 21.98 g = 0.02198 kg.
delta T = Kf*m. Substituting into the equation we have
freezing point benzene - 4.25 = delta T.
Substitute into delta T = Kf*m and solve for m = molality.
Then molality = moles/kg solvent and I've solved for kg solvent above and solve for moles, then mols = grams/molar mass. You have mols and grams, solve for molar mass. Post your work if you get stuck.
A 1.45 g sample of an unknown compound is dissolved in 25.00 mL benzene (d=0.879 g/mL). The solution freezes at 4.25 C. What is the molar mass of the unknown?
1 answer
1 answer