[biomed77]

i have to solve a problem for my assignment that involves copper complex. the equation is:
Cu2+ + EDTA4-  <--->  [Cu(EDTA)4]2-

a) the problem asks for an expression for the equilibrium constant: my answer is:
Kc= [Cu(EDTA)4]2- / [Cu2-][EDTA4-]

The second part asks: if the concentration of free EDTA4- ions in the blood can be risen to 1*10^-8mol dm^-3  and someone excretes the copper complex at a concentration of 1.5*10^-8mol dm^-3, estimate a value for the concentration of free copper ions in their body.[Kc= 1.6*10^18mol^-1dm^3]
so i did: 1.6*10^18 = 1.5*10^-8 / x*1*10^-8
x= 1.6*10^18 *1.5*10^-8 / 1*10^-8   x= 2.4*10^10 / 1*10^-8  x=240
can someone please tell me if my working is correct?? thanks

[Albert]

Do you really believe it's possible to have 240M as concentration of copper in our blood?!

[biomed77]

no, not really, i ll do it again...

[Albert]

x= 1.6*10^18 *1.5*10^-8 / 1*10^-8  

Here there's a clear mistake.

[biomed77]

i know, something is really wrong with me lately...

1.6*10^18=1.5*10^-8 / 1*10^-8
x= 1.5*10^-8 / 1.6*10^18 * 1*10^-8   x= 9.37 * 10^-19

hope its right now....

[Albert]

It's, of course.