CBSE Class 12 · 2002 · All India · SolutionsShort Answer

Calculate the number of moles of methanol in 5 litres of its 2 m solution, if the density of the solution is 0.981 kg L

^{- 1}

. (Molar mass of methanol = 32 g mol

^{- 1}

)

Answer: ≈ 9.2 mol

Solution

2 m solution: 2 mol (64 g) methanol per 1000 g of water, i.e. per

1064

g of solution.
Mass of 5 L of solution:

5 \times 0.981 = 4.905 kg = 4905 g

Mass of methanol in it:

4905 \times \frac{64}{1064} = 295.0 g

Moles of methanol:

\frac{295.0}{32}

= 9.22 mol

CBSE Class 12 Board · 2002 · All India · Subjective