# What is the molarity of a solution prepared when 75.0 mL of a 4.00 M KCl solution is diluted to 500 mL?step by step analysis

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Expert Answers

mlsiasebs | Certified Educator

In this problem we are dealing with dilution of a solution. The moles of KCl in the solution do not change only the volume in which they are dissolved. Remember that molarity, M, is moles of solute divided by Liters of solution. The formula we can use to determine the concentration is

M1V1 = M2V2

Where M1 and M2 are the initial and final concentrations, respectively and V1 and V2 are the initial and final volumes", respectively. Given the dilution formula, we can plug in our known values to solve for M2. We expect the concentration to decrease since we will have the same number of moles in a larger volume of solution.

(4.00 M)(75.0 mL) = M2(500 mL).

We can use the volumes in mL instead of L as long as both volumes are in the same units. When we solve for M2 = 0.600 M KCl

M1V1 = M2V2

Where M1 and M2 are the initial and final concentrations, respectively and V1 and V2 are the initial and final volumes", respectively. Given the dilution formula, we can plug in our known values to solve for M2. We expect the concentration to decrease since we will have the same number of moles in a larger volume of solution.

(4.00 M)(75.0 mL) = M2(500 mL).

We can use the volumes in mL instead of L as long as both volumes are in the same units. When we solve for M2 = 0.600 M KCl