Question

The mediator for the DSSC is an iodide electrolyte solution. If you need 5 mL of an iodide electrolyte solution, what masses (in grams) of KI and l₂ would you need if you want the final concentration to be 0.5M KI and 0.05M I₂? Record your values to three decimal places.

Answer 1

To create a 0.5M KI and 0.05M I₂ solution, you would need 0.415 grams of KI and 0.317 grams of I₂.

Step-by-step explanation:

To calculate the mass of KI and I₂ needed to create a 0.5M KI and 0.05M I₂ solution, we need to use the given concentration and volume. The formula for molarity (M) is:

Moles of solute = (Molarity) x (Volume in liters)

First, convert the volume of the solution to liters:

5 mL = 0.005 L

Next, calculate the moles of KI using the given concentration:

Moles of KI = (0.5 M) x (0.005 L) = 0.0025 moles

Finally, calculate the grams of KI by multiplying the moles by the molar mass of KI (166.0028 g/mol):

Grams of KI = (0.0025 moles) x (166.0028 g/mol) = 0.415 grams

To find the grams of I₂, we can use the stoichiometry of the reaction between KI and I₂:

2 KI + I₂ → 2 KI₃

From this balanced equation, we can see that 2 moles of KI react with 1 mole of I₂. Since we have 0.0025 moles of KI, we will need half that amount of I₂:

Moles of I₂ = 0.0025 moles / 2 = 0.00125 moles

Finally, calculate the grams of I₂ by multiplying the moles by the molar mass of I₂ (253.8 g/mol):

Grams of I₂ = (0.00125 moles) x (253.8 g/mol) = 0.317 grams