Question

An alcoholic iodine solution ("tincture" of iodine) is prepared by dissolving 213.95 g of iodine crystals in enough alcohol to make a volume of 357.79 mL. Calculate the molarity of iodine in the solution.

Answer 1

The molarity of iodine in the solution = 4.7122 mol/L

Step-by-step explanation

Given:

Mass of iodine = 213.95 g

Volume of the solution = 357.79 mL

What to find:

The molarity of iodine in the solution.

Step-by-step solution:

The molarity of iodine in the solution can be calculated using the molarity formula below.

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

Moles of iodine in 213.95 g iodine can be known using the mole formula.

The molar mass of iodine = 126.90 g/mol

`Mole=\frac{Mass}{Molar\text{ }mass}=\frac{213.95\text{ }g}{126.90\text{ }g\text{/}mol}=1.685973207\text{ }mol`

Also, volume in L = (357.79mL/1000 mL) x 1 L = 0.35779 L

Putting the values of mole and volume in L into the molarity formula above, we have;

`Molarity=\frac{1.685973207\text{ }mol}{0.35779\text{ }L}=4.7122\text{ }mol\text{/}L`

Therefore, the molarity of iodine in the solution is 4.7122 mol/L