Question

If the molality of methanol in an aqueous solution is 6 then
the mass percentage of methanol in the solution will be
24.2%
16.1%
8.4%
31.5%

Answer 1

Given info : if the molality of methanol in an aqueous solution is 6.

To find : the mass percentage of methanol in the solution will be

solution : molar mass of methanol = 32 g/mol

            molality of the molality if the solution = 6 molal

let mass of solvent has taken is 100g

so, molality = mole of methanol/mass of solvent in kg

⇒ 6 = (mass of methanol/32g/mol)/0.1 kg

⇒ 0.6 ×32 = mass of methanol

⇒ 19.2 g = mass of methanol

so the mass of solution = mass of methanol + mass of solvent

= 19.2 + 100 = 119.2 g

percentage mass of methanol = mass of methanol/mass of solution × 100

= 19.2/119.2 × 100

= 16.1 %

Therefore the mass percentage of methanol in the solution is 16.1 %