Question

1. The preparation of nanoparticle solutions adds a reducing reagent, sodium borohydride, to an oxidizing agent, hydrogen peroxide. Is it concievable that these two reagents would react with each other?

2. Why is it important to force the regression line in the Beer's Law plot of absorbance vs. concentration to go through the origin? Would adding the point (0,0) to your data set have the same effect? Why or why not?

I'm in intro chem so pleasee give in simple terms. Don't go too into depth

Answer 1

1. Yes, they could react with each other by redox reaction. Sodium borohydride is used to convert metal ions to solid nanoparticles. On the other hand, hydrogen peroxide is used to convert solid metals to their ionic form. But, usually in preparation of nanoparticle solutions, their concentrations are different wherein one is much higher compared to another so that there is an excess to react with the metal/metal ion.

2. It is done by adding a blank solution (containing no analyte or the compound of interest) and forcing its reading/response to zero. A blank or zero analyte concentration standard must have a zero response, since there is no analyte present in it. It is important to go through the origin so that you can be sure that the response of the solutions that contains analyte is the response only coming from the analyte and not from any other sources.

Adding (0,0) in the data would not have the same effect because if you only add (0,0) in the data and not doing blank reading (as above), the error due to response due to other sources is not eliminated. Consider this example.

you measure the absorbance of a blank standard, and it gave a response of 0.002. So you forced it to zero response by deducting 0.002 to each consequent reading. (another way of forcing zero is zeroing the response in the instrument)

   std.         absorbance             forcing through origin (deduct 0.002)

     0                  0.002                              0.000

     1                 0.010                               0.008

     2                 0.020                              0.018

     3                 0.030                               0.028

    but if you made it this way,

   no blank reading, only add (0,0) in the data, you end up having the data

   std.         absorbance            

     0                  0.000 (just added, no blank reading)                      

     1                 0.010                              

     2                 0.020                           

compare the R²or the equation of the line of the two (I dare you, it would be very different)