Question

6.84g of sucrose is dissolved in 200g water. The molality of the solution is:

• A. 0.2 M
• B. 0.3M
• C. 0.1 M
• D. 0.02 M

Answer 1

Answer: (C)

0.1 M

Molality is defined as the number of moles of solute per kilogram of solvent.

So, no of moles of solute, $n=\frac{m}{M}=\frac{6.84}{342}$

Weight of solvent is $\frac{200}{1000}=0.2Kg$

$Molality=\frac{\left(\frac{6.84}{342}\right)}{0.2}$

$\Rightarrow x=0.02/0.2=0.1M$