Question

A 1000 g of an aqueous solution containing 2 mol of ethanol has a density of 1.025 g/mL. Calculate the molarity of the solution.

• A. 2.05 M
• B. 2.50 M
• C. 3.15 M
• D. 1.25 M

Answer 1

The correct option is A 2.05 M

$M=\frac{n_{\text{solute}}}{\text{volume of solution (mL)}}\times 1000$
$M=\frac{2\times 1000}{\text{volume of solution (mL)}}$.........…(i)
Now, density is given by:
$Density=\frac{\text{mass of solution}}{\text{volume of solution}}$
$Volumeofsolution=\frac{1000g}{1.025g/mL}=975.61mL$
Putting the value of volume in eq (i) we get,
$Molarity\left(M\right)=\frac{2\times 1000}{975.61}=2.05$
Therefore, the molarity of the given solution is 2.05 M