Question

If 20.0 mL of a 0.0800 M HNO3, 35.0 mL of a 0.0800 M KSCN, and 40.0 mL of a 0.0800 M Fe(NO3)3 are combined, what is the initial concentration of SCN- in the mixture

Answer 1

0.0295M

Step-by-step explanation:

As you can see, in the mixture you have KSCN and other compounds. The KSCN in solution is dissolved in K⁺ ions and SCN⁻ ions. That means initial concentration of SCN⁻ ions is the same of KSCN, 0.0800M.

You are adding 35.0mL of this solution and the total volume of the mixture is 20.0mL + 35.0mL + 40.0mL = 95.0mL.

That means you are diluting your solution 95.0mL / 35.0mL = 2.714 times.

And the concentration of SCN⁻ is:

0.0800M / 2.714 =

0.0295M