Question

1. a 0.750 l aqueous solution contains 90.0 g of ethanol, c₂h₅oh. calculate the molar concentration of the solution in mol·l⁻¹. (ans:2.60mol/l)

Explanation:

Step1: Calculate molar mass of ethanol

Ethanol formula: \( C_2H_5OH \). Molar mass \( M = 2\times12.01 + 6\times1.008 + 16.00 = 46.07 \, \text{g/mol} \)

Step2: Calculate moles of ethanol

Moles \( n = \frac{\text{mass}}{\text{molar mass}} = \frac{90.0 \, \text{g}}{46.07 \, \text{g/mol}} \approx 1.9535 \, \text{mol} \)

Step3: Calculate molar concentration

Molarity \( c = \frac{n}{V} \), \( V = 0.750 \, \text{L} \). So \( c = \frac{1.9535 \, \text{mol}}{0.750 \, \text{L}} \approx 2.60 \, \text{mol/L} \)

Answer:

\( 2.60 \, \text{mol/L} \)