Ncert Exercises & Solutions

1.11 What is the concentration of sugar (C₁₂H₂₂O₁₁) in mol L^–1if its 20 g are dissolved in enough water to make a final volume up to 2L?

Molarity (M) of a solution is given by,

$= \frac{Number of moles of solute}{Volume of solution in liters}$
$= \frac{Mass of sugar / molar mass of sugar}{2 L}$
$= \frac{20 g / [(12 \times 12) + (1 \times 22) + (11 \times 16) g]}{2 L}$
$= \frac{20 g / 342 g}{2 L}$
$= \frac{0.0585 mol}{2 L}$