Question

What mass of KCl is required to make 46 mL of a 0.10 M KCl solution?

____________ g KCl

    How many moles of potassium ions are present in the solution?

____________ mol

Answer 1

molarity = 0.10 M

volume = 46 mL = 0.046 L

molarity = moles / volume

moles = molarity x volume

          = 0.10 x 0.046

          = 4.6 x 10^-3

molar mass of KCl = 74.55 g / mol

mass = moles x molar mass

         = 4.6 x 10^-3 x 74.55

        = 0.343 g

mass of KCl = 0.34 g

moles of KCl = 4 .6 x10^-3

moles of K+ ions = 0.0046