Question

What is the molarity of a solution made using 2.08 g of KI dissolved in enough water to make 279 mL of solution?

Answer 1

Molarity is defined as:

Number of moles of solute (KI) per liter of solution (KI + water)

We also need the molar mass of KI, equal to 166 g/mol

Procedure:

The number of moles of KI = 2.08 g/166 g/mol = 0.0125 moles KI

Volume = 279 mL = 0.279 L (1 L = 1000 mL)

Therefore,

0.125 moles KI ------- 0.279 L of solution

X ------- 1 L of solution

X = 0.448 mol/L

Another procedure:

Molarity = number of moles (KI)/Volume of solution (L)

Molarity = 0.125 moles/0.279 L = 0.448 mol/L or M

Answer: M = 0.448 mol/L