The formula of determining the molarity is:
molarity = [tex]\frac{moles of solute}{volume of solution in liters}[/tex] -(1)
Volume of solution = [tex]220.0 mL[/tex] (given)
Since, 1 mL = 0.001 L
Therefore, volume of the solution = 0.22 L
Molarity = 0.194 M (given)
Substituting the values in formula (1)
[tex]0.194 = \frac{moles of solute}{0.22}[/tex]
[tex]moles of solute= 0.22 L\times 0.194 mole/L = 0.0427 mole[/tex]
Now, number of moles = [tex]\frac{mass}{Molar mass}[/tex] -(2)
Molar mass of [tex]KMnO_4[/tex] = [tex]39.0983+54.938+4\times 15.99 = 158.0323 g/mol[/tex]
Substituting the value of number of moles and molar mass of [tex]KMnO_4[/tex] in equation -(2)
[tex]0.0427 mole = \frac{mass}{158.0323 g/mole}[/tex]
[tex]mass = 158.0323 g/mole\times 0.0427 mole = 6.748 g[/tex]
Hence, the mass in grams of potassium permanganate the chemist has added to the flask is [tex]6.748 g[/tex].
