Calculating the Mole Fraction of KI in 20% Aqueous Solution

To calculate the mole fraction of KI in a 20% aqueous solution, we need to follow the steps below:

Step 1: Find the Mass of KI in the Solution
Assuming we have 100g of the 20% (mass/mass) aqueous KI, we can calculate the mass of KI present in the solution as follows:

Mass of KI = 20% x 100g = 20g

Step 2: Find the Mass of Water in the Solution
The mass of water in the solution can be calculated by subtracting the mass of KI from the total mass of the solution:

Mass of Water = 100g - 20g = 80g

Step 3: Calculate the Number of Moles of KI Present
The number of moles of KI present can be calculated using the formula:

Moles of KI = Mass of KI / Molar Mass of KI

The molar mass of KI is 166 g/mol. Therefore:

Moles of KI = 20g / 166 g/mol = 0.1205 mol

Step 4: Calculate the Number of Moles of Water Present
The number of moles of water present can be calculated using the formula:

Moles of Water = Mass of Water / Molar Mass of Water

The molar mass of water is 18 g/mol. Therefore:

Moles of Water = 80g / 18 g/mol = 4.4444 mol

Step 5: Calculate the Mole Fraction of KI
The mole fraction of KI can be calculated using the formula:

Mole Fraction of KI = Moles of KI / (Moles of KI + Moles of Water)

Therefore:

Mole Fraction of KI = 0.1205 mol / (0.1205 mol + 4.4444 mol) = 0.0264

Therefore, the mole fraction of KI in the 20% aqueous KI solution is 0.0264.