Answer :
Final answer:
The percent by mass of magnesium nitrate in the 0.298 molal aqueous solution is 4.23%.
Explanation:
To calculate the percent by mass of magnesium nitrate in the solution, you first need to understand the concept of molality, which is defined as the number of moles of solute divided by the mass of the solvent (in kilograms). According to the given problem, the molality of the aqueous solution is 0.298 molal, meaning there is 0.298 mol of magnesium nitrate in every 1 kilogram of water. The molar mass of magnesium nitrate is approximately 148.32 g/mol, so the mass of magnesium nitrate in the solution is (0.298 mol)(148.32 g/mol) = 44.18 g. The mass of water in the solution is 1000 g. Therefore, the percent by mass of magnesium nitrate in the solution is (44.18 g) / (44.18 g + 1000 g) * 100% = 4.23%.
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