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Chemistry IA - transition metals

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My research question is "How does the size of the transition metal central ion affect the stability (or formation?) of a complex ion?" How can I figure out the stability of a complex ion by using colorimeter readings? Or just in general, what kind of information can I get out of colorimeter readings? I took 8 trials of 5 different metals using the ligand NH3 every time and I got a bunch of graphs out of them (well just three because the last two read 0). I just don't know how to analyse these graphs. Thanks for any help. 

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I cannot tell you how to analyze your data. The colorimeter is a type of absorbance photospectrometer, in which sufficiently dilute solutions follow the Beer-Lambert Law. In addition, a colorimeter can generally predict the apparent color of the complex ion, which is the color you see. Your data does not answer your RQ so your best bet is to change RQ such that it can be answered by data, which I leave you to do. Best luck!

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10 minutes ago, kw0573 said:

I cannot tell you how to analyze your data. The colorimeter is a type of absorbance photospectrometer, in which sufficiently dilute solutions follow the Beer-Lambert Law. In addition, a colorimeter can generally predict the apparent color of the complex ion, which is the color you see. Your data does not answer your RQ so your best bet is to change RQ such that it can be answered by data, which I leave you to do. Best luck!

Thanks for the information. One more thing though, perhaps is it possible to use the colorimeter data to work out the formula of the complex ion and then somehow tailor a new RQ to that? At different points on the graph, does the complex ion have a different formula which I can then use to determine the ratio of water to NH3? FYI, in my experiment, I added different volumes of NH3 to 5 different transition metal sulfates. 

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My guess that you cannot work out the formula of the complex ion from colorimeter unless compare to some known sample. 

Again, you need some graphs of pure ions (ie pure tetrahedral and pure octahetral) to make some comparisons to know the ratio of multiple complex ions. In which case you would solve (use a computer) a system of equations. However, you are often ending up with more constraints than variables so you would use the MS Excel "Solver" add-in to approximate the mol ratios. 

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1 hour ago, kw0573 said:

My guess that you cannot work out the formula of the complex ion from colorimeter unless compare to some known sample. 

Again, you need some graphs of pure ions (ie pure tetrahedral and pure octahetral) to make some comparisons to know the ratio of multiple complex ions. In which case you would solve (use a computer) a system of equations. However, you are often ending up with more constraints than variables so you would use the MS Excel "Solver" add-in to approximate the mol ratios. 

I dug around a bit more on the internet and found this: https://www.saddleback.edu/faculty/cabel/Saddleback/Chem_1B_Schedule_files/Exp23-complex-ion.pdf 
It looks like I can use the data to find the formula but I will need to first calculate the mole ratio then plot it against absorbance then extrapolate it... Is that what you were talking about? Also, I don't understand that last sentence of yours, how am I going to use the MS Excel Solver? So sorry for all these questions - I just can't get in touch with my teacher. Thank you. 

Edit: When calculating the mole ratio, would I also include the values of (NH4)2SO4 as well as NH3 and the metal ion? Or should the calculation just involve the ligand and the metal? 

Edited by red_hypergiant

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https://support.office.com/en-us/article/Load-the-Solver-Add-in-612926fc-d53b-46b4-872c-e24772f078ca, also https://support.office.com/en-us/article/Define-and-solve-a-problem-by-using-Solver-9ed03c9f-7caf-4d99-bb6d-078f96d1652c

I was saying something very similar. Essentially in a paint comparison, it would be you got a shade of purple (final spectra of a mixture of ions), and you do some analysis to figure out what ratio of red and blue (spectra of pure ions) was added. Hint, when set up correctly, the solver takes a lot of equations based on Beer-Lamber Law and returns a set of ratio of red and blue that best fit all the equations. 

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Hi I was also doing an experiment using transition metals but in my experiment I want to use them as catalyst. I was wondering if an increase in the mass of the transition metal would have an effect on the final temperature or pH of the solution. Could someone let me know if it will.

 

In case that didn't work, I was trying to find the mass of the transition metal that would produce the optimum pH or temperature. Would I be testing for the optimum temperature of the solution or the catalyst itself and how would I find it.

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