Harrison W. answered • 04/16/20

Yale grad, 100th percentile MCAT, applying to med school

Hey Duch! Thanks for your question.

Here, it's probably easiest to use the equation C1*V1 = C2*V2, where "C" stands for concentration and "V" stands for volume. You can rearrange the equation to read: V1 = (C2*V2)/C_{1}

If you want a final solution of 100mL and a concentration of 0.35M, plug those values in to the numerator on the right side of the equation. You know your initial concentration (C_{1}) is 0.75M, so you can plug that in too. From there, its just a simple calculation:

V_{1} = (0.35M * 100mL) / 0.75M

V_{1} = 46.67mL

So in your final solution, you'll need 46.67mL of stock KCl, and the rest (53.33mL) will be water.

Hope this helps!!