An aqueous solution of a compound with a molar mass of 34.02 g/mol is 24.5% by mass and has a density of 1.09 g/cm³. What is the molarity of the solution? A) 7.85 M B) 7.20 M C) 1.31 M D) 0.000785 M E) 6.61 M

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To find the molarity of the solution, we first calculate the mass of solute per 100 g of solution, since the solution is 24.5% by mass. This means there are 24.5 g of the compound in 100 g of solution. The molar mass of the compound is given as 34.02 g/mol, so the number of moles of the compound in 100 g of solution is $ \frac{24.5 \, \text{g}}{34.02 \, \text{g/mol}} = 0.720 \, \text{mol} $.The density of the solution is 1.09 g/cm³, which means 1 mL of the solution has a mass of 1.09 g. Therefore, 100 g of the solution has a volume of $ \frac{100 \, \text{g}}{1.09 \, \text{g/mL}} = 91.74 \, \text{mL} $ or 0.09174 L.The molarity (M) is the number of moles of solute per liter of solution, so the molarity of the solution is $ \frac{0.720 \, \text{mol}}{0.09174 \, \text{L}} = 7.85 \, \text{M} $.

An Aqueous Solution of a Compound with a Molar Mass