What is the Molarity of a 5.00% (m/m) aqueous NH₃ solution?
(Density of solution = 0.9651 g/mL)

Question

What is the Molarity of a 5.00% (m/m) aqueous NH₃ solution? (Density of solution = 0.9651 g/mL)

Quizplus · Accepted Answer

To calculate the molarity of the solution, first, we need to understand the given information. A 5.00% (m/m) solution means there are 5.00 grams of solute (NH₃) per 100 grams of solution. The density of the solution is 0.9651 g/mL, which means 1 mL of the solution weighs 0.9651 grams.1. Calculate the mass of the solution that would contain 5.00 grams of solute:$$ \text{Mass of solution} = \frac{100 \text{ grams of solution}}{5.00 \text{ grams of solute}} \times 5.00 \text{ grams of solute} = 100 \text{ grams} $$2. Calculate the volume of this solution using its density:$$ \text{Volume of solution} = \frac{\text{Mass of solution}}{\text{Density of solution}} = \frac{100 \text{ grams}}{0.9651 \text{ g/mL}} \approx 103.61 \text{ mL} $$3. Convert the volume from mL to L (since molarity is moles per liter):$$ 103.61 \text{ mL} = 0.10361 \text{ L} $$4. Calculate the number of moles of solute (assuming the molecular formula is correct and represents a real compound, which seems not to be the case, but we'll proceed with the calculation method):$$ \text{Moles of solute} = \frac{\text{Mass of solute}}{\text{Molar mass of solute}} $$Without the actual molar mass of the solute, we cannot proceed with this step accurately. However, the question seems to be theoretical or might contain a typographical error in the chemical formula. Assuming we had the molar mass, we would divide the mass of the solute (5.00 grams) by its molar mass to find the moles.5. Calculate molarity:$$ \text{Molarity (M)} = \frac{\text{Moles of solute}}{\text{Volume of solution in liters}} $$Given the choices and without the exact molar mass of the solute, we cannot accurately calculate the molarity. However, if we were to follow through with hypothetical or provided values for the molar mass, we would use the formula in step 5 to find the molarity. The correct answer, based on the choices provided and assuming there's a specific calculation or approximation method expected, is selected as A) 2.83 M, but it's important to note that without the molar mass of the solute, this step is purely speculative based on the options given.

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