Determining Initial and Equilibrium Concentration (Help )

[galaticman]

Determining Initial and Equilibrium Concentration (Help!)

Homework Statement

You are given the equation Fe³⁺ + SCN^- -> FeSCN^-
You are performing an experiment in which you are mixing Fe(NO₃)₃ and NaSCN. A table is given and I will only list the first sets of data because if i can figure out the process for the first one I can figure out the rest. The table is:

10 mL of 2.0x10^-3 M Fe(NO³)₃
2mL of 2.0x10^-3
Total Volume of Solution: 50mL

You are asked to to calculate the initial SCN^- concentration (M) as well as the equilibrium FeNCS²⁺ concentration (M)

I am just not sure how to go about doing that. Any help would be greatly appreciated!

NOTE: It also mentions that to assume all of the SCN^- is present as FeNCS²⁺ but I am pretty sure that this is irrelevant and is relevant to the later part of the lab

 

[Borek]

So, if I understand you correctly, you take 2 mL of 2x10^-3M solution of SCN^-, and you dilute it up to 50 mL (other solution doesn't matter at this moment)?

How many moles of SCN^- in these 2 mL? What is the concentration of the solution containing this amount of SCN^- in a 50 mL volume?

 

[galaticman]

Yup that is pretty much it except it is not just SCN it is NaSCN but I am not sure if that matters for the problem or not?

 

[Borek]

It doesn't matter - if the solution is 2x10^-3 M in NaSCN, it is also 2x10^-3 M in Na⁺ and SCN^-.

 

[galaticman]

Ohhhh okay I got it then! Thanks!