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Determining Initial and Equilibrium Concentration (Help )

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galaticman
#1
Mar2-12, 01:17 AM
P: 8
1. The problem statement, all variables and given/known data
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
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Borek
#2
Mar2-12, 02:48 AM
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P: 23,568
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
#3
Mar2-12, 03:26 AM
P: 8
Yup that is pretty much it except it is not just SCN it is NaSCN but Im not sure if that matters for the problem or not?

Borek
#4
Mar2-12, 04:19 AM
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Determining Initial and Equilibrium Concentration (Help )

It doesn't matter - if the solution is 2x10-3 M in NaSCN, it is also 2x10-3 M in Na+ and SCN-.
galaticman
#5
Mar2-12, 12:01 PM
P: 8
Ohhhh okay I got it then! Thanks!!!!!


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