Multiple Choice
What is the molarity of Br⁻ ions in a solution that is 0.200 M KBr?
6. Chemical Quantities & Aqueous Reactions
Molarity
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What is the molarity of a 12.2% by mass glucose (C6H12O6) solution if the density of the solution is 1.03 g/mL?
A
0.500 M
B
1.200 M
C
0.850 M
D
0.695 M
Verified step by step guidance1
Start by understanding that molarity (M) is defined as the number of moles of solute (in this case, glucose) per liter of solution. The formula is: M = \( \frac{\text{moles of solute}}{\text{liters of solution}} \).
Calculate the mass of glucose in a given mass of solution. Since the solution is 12.2% by mass glucose, this means there are 12.2 grams of glucose in every 100 grams of solution.
Determine the volume of the solution using its density. Given the density is 1.03 g/mL, convert the mass of the solution (100 g) to volume: \( \text{Volume} = \frac{\text{mass}}{\text{density}} = \frac{100 \text{ g}}{1.03 \text{ g/mL}} \). Convert this volume from mL to L for use in the molarity formula.
Calculate the number of moles of glucose. Use the molar mass of glucose (C6H12O6), which is approximately 180.18 g/mol: \( \text{moles of glucose} = \frac{12.2 \text{ g}}{180.18 \text{ g/mol}} \).
Finally, calculate the molarity of the solution by dividing the moles of glucose by the volume of the solution in liters: \( M = \frac{\text{moles of glucose}}{\text{liters of solution}} \).
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