Question

How many grams of glucose dissolved in 1 litre of water will give its 1 M solution?

• A. 96 g
• B. 120 g
• C. 180 g
• D. 240 g

Answer 1

The correct option is C

180 g

The volume of the aqueous solution = 1 L

Molarity of the solution = 1

Molarity of a solution is given by the formula = $\frac{\text{Number of moles of solute}}{\text{Volume of the solution (litres)}}$ ....(i)

$\therefore$ Number of moles of solute = Molarity of a solution (M) x Volume of the solution (litres) ....(ii)

Substituting the value of molarity of the solution and volume of the solution in equation (ii) we have

Number of moles of solute = 1 x 1
Number of moles of solute = 1

Molecular mass of Glucose, $C_6{H}_{12}{O}_6$

= 6 x Atomic mass of carbon + 12 x Atomic mass of hydrogen + 6 x Atomic mass of oxygen
= 6 x 12 + 12 x 1 + 6 x 16
= 180 u

GMM of glucose = 180 g.

Number of moles of solute = $\frac{\text{Mass}}{\text{Gram molecular mass}}$

Required mass = Number of moles of solute x Gram molecular mass

Mass = 1 x 180 = 180

$\therefore$ 180 g of glucose in 1 litre of water will give 1 M solution.