Answer with Explanation:
To determine the amount of water needed to dilute a 2.5 M KCl solution to a 1.0 M solution, we can use the dilution formula:
M1V1 = M2V2
where M1 is the initial concentration, V1 is the initial volume, M2 is the final concentration, and V2 is the final volume.
In this case, we know that:
M1 = 2.5 M
V1 = 550 mL
M2 = 1.0 M
We want to find V2, the final volume of the solution, which will be greater than 550 mL due to the addition of water.
Using the dilution formula, we can solve for V2:
M1V1 = M2V2
2.5 M x 550 mL = 1.0 M x V2
V2 = (2.5 M x 550 mL) / 1.0 M
V2 = 1375 mL
Therefore, we would need to add 1375 mL - 550 mL = 825 mL of water to 550 mL of a 2.5 M KCl solution to make a 1.0 M solution.