An aqueous solution contains 24.2 g of KCl and is diluted to 100. mL. What is the mole fraction of KCl in the solution if the density is 1.12 g/mL?
To find the mole fraction of KCl in the solution, we need to first calculate the number of moles of KCl present and then divide it by the total number of moles of all components in the solution (water + KCl).
Step 1: Calculate the moles of KCl
We are given that the solution contains 24.2 g of KCl. To find the number of moles, we need to divide the given mass by the molar mass of KCl.
The molar mass of KCl is calculated as follows:
Molar mass of K: 39.10 g/mol
Molar mass of Cl: 35.45 g/mol
Molar mass of KCl = 39.10 g/mol + 35.45 g/mol = 74.55 g/mol
Number of moles of KCl = mass of KCl / molar mass of KCl
= 24.2 g / 74.55 g/mol
Step 2: Calculate the total moles in the solution
To calculate the total moles in the solution, we need to know the volume and density of the solution. We are given that the solution is diluted to 100 mL and has a density of 1.12 g/mL.
The mass of the solution can be calculated using the density formula:
Mass = density * volume
= 1.12 g/mL * 100 mL
Number of moles of the solution = mass of the solution / molar mass of the solution
Step 3: Calculate the mole fraction
The mole fraction can be calculated by dividing the moles of KCl by the total moles in the solution.
Mole fraction of KCl = moles of KCl / total moles in the solution
By substituting the values obtained from Step 1 and Step 2 into this equation, you will get the mole fraction of KCl in the solution.