Question

You dissolve 0.62 g of potassium chloride (KCl) in 600 ml of water.What is the molarity of the solution?(From the periodic table: 1 mol K = 39.10 g; 1 mol Cl = 35.453 g)Enter the value rounded to three decimal places with no unitsPlease help

Answer 1

ANSWER

The molarity of the solution is 0.014

EXPLANATION

Given that;

The mass of the dissolved KCl is 0.62g

The volume of water is 600ml

Follow the steps below to find the molarity of the solution

Step 1; Find the molar mass of the solute

$\begin{gathered} \text{ Given;} \\ \text{ 1 mol K = 39.10 g and 1 mol Cl is 35.453g} \\ \text{ KCl = 39.10 + 35.453} \\ \text{ 1 mol KCl = 74.553g} \end{gathered}$

Therefore, the molar mass of KCl is 74.553 g/mol

Step 2; Convert the volume of the solution to L

Recall, that 1 mL is equivalent to 0.001L

$\begin{gathered} \text{ 1mL }\rightarrow\text{ 0.001L} \\ \text{ 600mL }\rightarrow\text{ xL} \\ \text{ cross multiply} \\ \text{ 1mL }\times\text{ xL = 600mL }\times\text{ 0.001L} \\ \text{ Isolate x} \\ \text{ x = }\frac{600\cancel{mL}\times0.001L}{1\cancel{mL}} \\ \text{ x = 600}\times\text{ 0.001} \\ \text{ x = 0.6L} \end{gathered}$

Step 3; Find the number of moles of KCl using the below formula

$\text{ mole = }\frac{\text{ mass}}{\text{ molar mass}}$$\begin{gathered} \text{ mole = }\frac{\text{ 0.62}}{\text{ 74.553}} \\ \text{ mole = 0.00831 mol} \end{gathered}$

Step 4; Find the molarity of the solution using the below formula

$\begin{gathered} \text{ Molarity = }\frac{\text{ mole of solute}}{\text{ volume of solution}} \\ \end{gathered}$$\begin{gathered} \text{ Molarity = }\frac{\text{ 0.00831}}{\text{ 0.6}} \\ \text{ molarity = 0.01385 M} \\ \text{ }Molarity\approx\text{ 0.014 M} \end{gathered}$

Therefore, the molarity of the solution is 0.014