Question

what is the concentration in molarity of an aqueous solution that contains 3.61% by mass ethylene glycol (molar mass = 62.07 g/mol)? the density of the solution is 1.04 g/ml.

Explanation:

Step1: Assume 100g of solution

Mass of ethylene glycol = $3.61\ \text{g}$

Step2: Calculate moles of ethylene glycol

Moles $n = \frac{\text{mass}}{\text{molar mass}} = \frac{3.61\ \text{g}}{62.07\ \text{g/mol}} \approx 0.05816\ \text{mol}$

Step3: Find volume of solution

Volume $V = \frac{\text{mass of solution}}{\text{density}} = \frac{100\ \text{g}}{1.04\ \text{g/mL}} = 96.1538\ \text{mL} = 0.0961538\ \text{L}$

Step4: Calculate molarity

Molarity $M = \frac{n}{V} = \frac{0.05816\ \text{mol}}{0.0961538\ \text{L}}$

Answer:

$0.605\ \text{mol/L}$