Final answer:
B) 16.4. The mass of sodium bromide in a 650 mL solution with a bromide ion concentration of 0.245 M is calculated by finding the number of moles of bromide ions and converting it to grams using the molar mass of NaBr, which results in 16.4 grams.
Step-by-step explanation:
The student is asking how to calculate the mass of sodium bromide in a solution with a given volume and molar concentration. To solve this, we first need to find the number of moles of bromide ions in the 650 mL solution, using the molarity (M) provided. Since the volume needs to be in liters for the molarity equation, we convert it: 650 mL is equivalent to 0.650 L. The number of moles can be found by multiplying the concentration by the volume in liters: 0.245 M* 0.650 L = 0.159375 moles of bromide ions.
Next, we need to convert moles of bromide ions to grams of sodium bromide (NaBr). The molar mass of NaBr is approximately 102.9 g/mol. The mass of NaBr can be calculated by multiplying the number of moles by the molar mass: 0.159375 mol * 102.9 g/mol = approximately 16.4 grams of NaBr. Therefore, the mass of sodium bromide in the solution is 16.4 grams (answer B).