Question

Calculate the concentration of an aqueous KCl solution if 431 mL of the solution gives 55.9 g of AgCl when treated with excess AgNO3. The equation for the reaction is

a) 0.25 mol/L

b) 0.50 mol/L

c) 0.75 mol/L

d) 1.00 mol/L

Answer 1

To calculate the concentration of the KCl solution, moles of AgCl produced were first determined and then used to calculate molarity. The calculated concentration is 0.905 M, with the nearest provided option being 0.75 mol/L.

Step-by-step explanation:

We need to calculate the concentration of KCl solution that gives 55.9 g of AgCl when treated with excess AgNO3. We use the stoichiometry of the reaction where KCl reacts with AgNO3 to form AgCl and KNO3. The reaction is:

AgNO3 + KCl → AgCl + KNO3

First, we find the moles of AgCl formed using its molar mass (143.32 g/mol). 55.9 g / 143.32 g/mol = 0.39 moles of AgCl. Since the reaction is in a 1:1 ratio, 0.39 moles of KCl were needed in the reaction.

To find the molarity of the KCl solution:

• Convert the volume of the KCl solution to liters: 431 mL × (1 L / 1000 mL) = 0.431 L
• Use the formula for molarity (Moles of solute / Volume of solution in liters): 0.39 moles / 0.431 L = 0.905 M

Looking at the answer choices, the closest option to the calculated concentration is 0.75 mol/L. There appears to be a slight discrepancy, which can be due to rounding differences or the answer choices provided are not matching exactly with the calculated value