College

Determine the molarity of a solution formed by dissolving 97.7 g LiBr in enough water to yield 750.0 mL of solution.

Given:
\[ \text{MW of LiBr} = 86.85 \, \text{g/mol} \]
\[ 1.00 \, \text{L} = 1000 \, \text{mL} \]

A. 1.50 M
B. 1.18 M
C. 0.130 M
D. 0.768 M
E. 2.30 M

Answer :

Sure, let's go through the solution step-by-step to determine the molarity of the LiBr solution.

### Step 1: Find the Number of Moles of LiBr

Given:
- Mass of LiBr = 97.7 g
- Molar Mass (MW) of LiBr = 86.85 g/mol

To find the number of moles of LiBr, we use the formula:

[tex]\[
\text{Number of moles} = \frac{\text{Mass}}{\text{Molar Mass}}
\][/tex]

[tex]\[
\text{Number of moles of LiBr} = \frac{97.7 \, \text{g}}{86.85 \, \text{g/mol}} \approx 1.1249 \, \text{mol}
\][/tex]

### Step 2: Convert Volume from mL to L

Given:
- Volume of the solution = 750.0 mL

To convert this to liters:

[tex]\[
\text{Volume in liters} = \frac{\text{Volume in mL}}{1000}
\][/tex]

[tex]\[
\text{Volume in liters} = \frac{750.0 \, \text{mL}}{1000} = 0.75 \, \text{L}
\][/tex]

### Step 3: Calculate the Molarity

Molarity (M) is defined as the number of moles of solute per liter of solution:

[tex]\[
\text{Molarity} = \frac{\text{Number of moles of solute}}{\text{Volume of solution in liters}}
\][/tex]

[tex]\[
\text{Molarity} = \frac{1.1249 \, \text{mol}}{0.75 \, \text{L}} \approx 1.5 \, \text{M}
\][/tex]

### Conclusion:
The molarity of the solution is approximately [tex]\( 1.5 \, \text{M} \)[/tex].

So, the correct answer is:
[tex]\[ 1.50 \, \text{M} \][/tex]

This matches the given options, confirming that our calculations were done correctly.

Other Questions