Question

What volume of a $0.8$ M solution contains $100$ millimoles of the solute?

• A. $100mL$
• B. $125mL$
• C. $500mL$
• D. $62.5mL$

Answer 1

The correct option is B $125mL$

Let V mL of a 0.8 M solution contains 100 millimoles of the solute
The number of moles of solute are $\frac{VmL}{1000mL/L}\times 0.8mol/L$
But this is equal to 100 millimoles or 0.1 mole.
Hence, $\frac{VmL}{1000mL/L}\times 0.8mol/L=0.1$
$V=\frac{0.1\times 1000}{0.8}=125mL$
Thus, 125 mL of a 0.8 M solution contains 100 millimoles of the solute.