Answer :
To determine the molarity of a solution formed by dissolving 97.7 g of LiBr in enough water to yield 750.0 mL of solution, follow these steps:
1. Understand the Concept of Molarity:
Molarity is defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (M).
2. Identify the Given Information:
- Mass of the solute (LiBr): 97.7 grams
- Volume of the solution: 750.0 mL
3. Find the Molar Mass of LiBr:
Lithium Bromide (LiBr) has a molar mass of approximately 86.845 grams per mole. This value is obtained by adding the atomic masses of lithium (Li) and bromine (Br).
4. Convert Volume from Milliliters to Liters:
Since molarity is expressed in terms of liters, convert the given volume:
[tex]\[
750.0 \, \text{mL} = 0.750 \, \text{L}
\][/tex]
5. Calculate Moles of LiBr:
Use the molar mass to convert the mass of LiBr to moles:
[tex]\[
\text{Moles of LiBr} = \frac{\text{Mass of LiBr}}{\text{Molar Mass of LiBr}} = \frac{97.7 \, \text{g}}{86.845 \, \text{g/mol}} \approx 1.125 \, \text{moles}
\][/tex]
6. Determine the Molarity of the Solution:
Use the formula for molarity:
[tex]\[
\text{Molarity} = \frac{\text{Moles of LiBr}}{\text{Volume of Solution in Liters}} = \frac{1.125 \, \text{moles}}{0.750 \, \text{L}} \approx 1.50 \, \text{M}
\][/tex]
Therefore, the molarity of the solution is approximately 1.50 M. The correct answer is option A) 1.50 M.
1. Understand the Concept of Molarity:
Molarity is defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (M).
2. Identify the Given Information:
- Mass of the solute (LiBr): 97.7 grams
- Volume of the solution: 750.0 mL
3. Find the Molar Mass of LiBr:
Lithium Bromide (LiBr) has a molar mass of approximately 86.845 grams per mole. This value is obtained by adding the atomic masses of lithium (Li) and bromine (Br).
4. Convert Volume from Milliliters to Liters:
Since molarity is expressed in terms of liters, convert the given volume:
[tex]\[
750.0 \, \text{mL} = 0.750 \, \text{L}
\][/tex]
5. Calculate Moles of LiBr:
Use the molar mass to convert the mass of LiBr to moles:
[tex]\[
\text{Moles of LiBr} = \frac{\text{Mass of LiBr}}{\text{Molar Mass of LiBr}} = \frac{97.7 \, \text{g}}{86.845 \, \text{g/mol}} \approx 1.125 \, \text{moles}
\][/tex]
6. Determine the Molarity of the Solution:
Use the formula for molarity:
[tex]\[
\text{Molarity} = \frac{\text{Moles of LiBr}}{\text{Volume of Solution in Liters}} = \frac{1.125 \, \text{moles}}{0.750 \, \text{L}} \approx 1.50 \, \text{M}
\][/tex]
Therefore, the molarity of the solution is approximately 1.50 M. The correct answer is option A) 1.50 M.