Question

You dissolve 0.66 g of potassium chloride (KCl) in 700 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 units

Answer 1

0.009 mol/L

Step-by-step explanation

Given:

Mass of KCl = 0.66 g

Volume of water = 700 mL = 0.7 L

From the periodic table: 1 mol K = 39.10 g; 1 mol Cl = 35.453 g

What to find:

The molarity of the solution

Step-by-step solution:

The formula to calculate molarity is:

`\text{Molarity }=\frac{Mole}{Volume\text{ in L}}`

The first step is to calculate the molar mass of KCl

KCl = Mass of 1 mol K + Mass of 1 mol Cl

KCl = 39.10 g + 35.453 g

KCl = 74.553 g

So the molar mass of KCl = 74.553 g/mol

The next step is to determine the number of moles of KCl in 0.66g of KCl:

`\text{Mole }=\frac{Mass}{Molar\text{ mass}}=\frac{0.66\text{ g}}{74.553\text{ g/mol}}=8.852762464*10^(-3)mol`

Put the values of mole and volume into the molarity formula above to determine the molarity of the solution:

`\begin{gathered} \text{Molarity }=\frac{8.852762464*10^(-3)\text{ mol}}{0.7\text{ L}}=0.00885276molL^(-1) \\ To\text{ thr}ee\text{ decimal places,} \\ \text{Molarity }=0.009\text{ }molL^(-1) \end{gathered}`

The molarity is 0.009 mol/L