The molar mass of [tex]$KCl[tex]$[/tex] is [tex]$[/tex]74.55 \, \text{g/mol}[tex]$[/tex]. If [tex]$[/tex]8.45 \, \text{g}[tex]$[/tex] of [tex]KCl[/tex] are dissolved in [tex]0.750 \, \text{L}$[/tex][/tex] of solution, what is the molarity of the solution?

Use [tex]\text{molarity} = \frac{\text{moles of solute}}{\text{liters of solution}}[/tex].

A. [tex]0.113 \, \text{M}[/tex]
B. [tex]0.151 \, \text{M}[/tex]
C. [tex]6.62 \, \text{M}[/tex]
D. [tex]11.3 \, \text{M}[/tex]



Answer :

To determine the molarity of the solution, we need to follow these steps:

1. Determine the number of moles of \( KCl \) present:

The formula to compute moles is:
[tex]\[ \text{moles of KCl} = \frac{\text{mass of KCl}}{\text{molar mass of KCl}} \][/tex]

Given:
- Mass of \( KCl \) = 8.45 g
- Molar mass of \( KCl \) = 74.55 g/mol

Plugging in the values:

[tex]\[ \text{moles of KCl} = \frac{8.45 \text{ g}}{74.55 \text{ g/mol}} \approx 0.1133 \text{ moles} \][/tex]

2. Calculate the molarity of the solution:

Molarity (\( M \)) is defined as:
[tex]\[ M = \frac{\text{moles of solute}}{\text{liters of solution}} \][/tex]

Given:
- Moles of \( KCl \) \(\approx 0.1133 \text{ moles}\)
- Volume of the solution = 0.750 L

Using the formula for molarity:

[tex]\[ M = \frac{0.1133 \text{ moles}}{0.750 \text{ liters}} \approx 0.1511 \text{ M} \][/tex]

So, the calculated molarity of the \( KCl \) solution is approximately 0.151 M.

Hence, the correct answer is:
[tex]\[ 0.151 \text{ M} \][/tex]