If you have 200 mL of a 0.50 M solution of KOH and you wish to dilute it to 0.30 M, how many mL of water should you add?
mL x M = mL x M
Then you want to add enough water to make the final volume the calculated volume.
To find out how many milliliters of water you should add, you need to consider the dilution formula:
C1V1 = C2V2
where:
C1 = initial concentration of the solution (0.50 M)
V1 = initial volume of the solution (200 mL)
C2 = final concentration of the solution (0.30 M)
V2 = final volume of the solution (V1 + volume of water)
First, let's rearrange the formula to solve for V2:
V2 = (C1V1) / C2
Now let's substitute the known values into the formula:
V2 = (0.50 M * 200 mL) / 0.30 M
V2 = (100 mL) / (0.30 M)
V2 ≈ 333.33 mL
So, you should add approximately 333.33 mL of water to your solution of KOH to achieve the desired concentration of 0.30 M.