[SuckingAtLife]

Hi Everyone,

So I'm stuck on a lab I did for a Gen. Chem. II class. I've tried contacting my lab and lecture professors and I haven't been able to get ahold of them. One doesn't do office hours at all, and the other has them when I have classes and I can't seem to get her to meet with me otherwise. Anyway, if anyone can help me with this, I'd would appreciate it SO SO SO much. I suck at chemistry, but I really have been trying very hard.

Here goes...

We conducted 10 trials for Fe3+ + SCN- <--> FeSCN2+ and we were told to record the absorbance value for each trial. The first 5 trials were the standards.

-Trial 1: Absorbance was .005, SCN- 1 mL, Fe 10 mL
-Trial 2: Absorbance .009, SCN- 2 mL, Fe 10mL
-Trial 3:Absorbance .028, SCN- 3mL, Fe 10 mL
-Trial 4:Absorbance .039 SCN- 4mL, Fe 10 mL
-Trial 5: Absorbance .054, SCN- 5mL, Fe 10mL

For the test solutions (tubes 6-10), I calculated or recorded the absorbance, moles of Fe (initial), moles of SCN- (Initial), and recorded the volumes.

We are supposed to chart the absorbance vs concentration for trials 6-10. I think it's the concentration of the FeSCN-, but I think my calculations are wrong for the concentration. Do I use the initial moles of SCN-? We are also supposed to get the Kc value of the trials from the graph, but I don't know what the Kc value pertains to. The slope? The final part is calculating the moles of reacted Fe and SCN-, as well as the moles of each at equilibrium. I'm so lost. Any help would be much appreciated and I'm eternally grateful.

[Corribus]

I'm just a pinch confused.  Trials 1-5 : these are based on known concentrations (stock solutions) of thiocyanate and iron?  And Tubes 6-10 are unknown solutions or something?  What information are you given for these?