Potassium bromide has a molar mass of . If I dissolve in of water, what is the concentration of for this solution? Report your answer with three significant figures.
The Correct Answer and Explanation is :
To calculate the concentration of potassium bromide (KBr) in a solution, we need to know the molar mass of KBr, the amount of KBr dissolved, and the volume of water used. Since you didn’t provide the exact mass of KBr or the volume of water, I will walk you through the process of finding the concentration based on general information. Feel free to provide those details so I can give you a specific answer!
Step 1: Determine the molar mass of KBr
The molar mass of potassium bromide (KBr) is the sum of the atomic masses of potassium (K) and bromine (Br).
- Potassium (K): approximately 39.10 g/mol
- Bromine (Br): approximately 79.90 g/mol
Thus, the molar mass of KBr is:
[
\text{Molar mass of KBr} = 39.10 \, \text{g/mol} + 79.90 \, \text{g/mol} = 119.00 \, \text{g/mol}
]
Step 2: Calculate the number of moles of KBr
To find the number of moles of KBr, use the formula:
[
\text{Moles of KBr} = \frac{\text{Mass of KBr (g)}}{\text{Molar mass of KBr (g/mol)}}
]
For example, if you dissolve 10 grams of KBr, the moles of KBr would be:
[
\text{Moles of KBr} = \frac{10 \, \text{g}}{119.00 \, \text{g/mol}} = 0.0840 \, \text{mol}
]
Step 3: Calculate the concentration
To find the concentration (in molarity, M), you need to know the volume of the water in which KBr is dissolved. The formula for molarity is:
[
\text{Molarity (M)} = \frac{\text{Moles of solute}}{\text{Volume of solution (L)}}
]
For instance, if the KBr is dissolved in 0.500 L (500 mL) of water, the concentration would be:
[
\text{Molarity (M)} = \frac{0.0840 \, \text{mol}}{0.500 \, \text{L}} = 0.168 \, \text{M}
]
Thus, the concentration of KBr would be 0.168 M.
Final Answer:
The concentration of KBr is 0.168 M when 10 grams of KBr are dissolved in 0.500 L of water.
If you provide the exact values for mass and volume, I can provide the precise calculation with three significant figures!