G山东我子大写 Analytical chemistry Fe3+H,OO [Fe(OH)]2 +H" Fe3+CI0 [FeCI]2 M Therefore,the total concentration of Fe()in the solution may be expressed as c(Fe)=Fe +[Fe(OH)+[FeCl]+L [Fe*] Where a is the side reaction coefficient of Fe3+,similarly,to the Fe2+ 2022/11/19
Analytical chemistry Therefore, the total concentration of Fe(Ⅲ) in the solution may be expressed as Where α is the side reaction coefficient of Fe3+ , similarly, to the Fe2+ 2022/11/19
归东理工大军 Analytical chemistry CFe [Fe2] =2 Taking the activity coefficient and the side reaction coefficient into account,we have i=j9+0.0591g e[Fe] 8e[Fe2+] =j9+0.0591g9 Fe2-a 2022/11/19
Analytical chemistry Taking the activity coefficient and the side reaction coefficient into account, we have 2022/11/19
G归东我工大图 Analytical chemistry When c(Fe3+)=c(fe2+)=1 mol/L The equation may be expressed as 7=j+0.0591g3:0心=j Where is called the conditional potential Obviously,the conditional potential of a couple is just the potential that is measured when the total concentration of both the oxidized and reduced forms are equal to 1 mol/L. Some factors may affect the conditional potential. 2022/11/19
Analytical chemistry When c(Fe3+)=c(fe2+)=1 mol/L The equation may be expressed as Where φ0 ' is called the conditional potential Obviously, the conditional potential of a couple is just the potential that is measured when the total concentration of both the oxidized and reduced forms are equal to 1 mol/L. Some factors may affect the conditional potential. 2022/11/19
山东工大军 Analytical chemistry (1).Ionic strength effect For a solution with high ionic strength,the activity coefficient is much less than 1.in this case,significant error will be introduced if the concentration is used in place of the activity for calculation involving Nernst equation.Because the effect of the ionic strength is much less significant than the side reaction,and it is more difficult to correct,it can be neglected in approximate estimation. (2).Side reaction effect Precipitation and complex formed reaction are usually used to change the concentration of the oxidized or reduced form in a redox reaction,so as to change the conditional potential of the coupeng
Analytical chemistry (1). Ionic strength effect For a solution with high ionic strength, the activity coefficient is much less than 1. in this case, significant error will be introduced if the concentration is used in place of the activity for calculation involving Nernst equation. Because the effect of the ionic strength is much less significant than the side reaction, and it is more difficult to correct, it can be neglected in approximate estimation. (2). Side reaction effect Precipitation and complex formed reaction are usually used to change the concentration of the oxidized or reduced form in a redox reaction, so as to change the conditional potential of the couple. 2022/11/19
©山东我工大 Analytical chemistry When a precipitating agent that can precipitate the oxidized form is added,the conditional potential of the couple decreases.If the reduced form precipitates,however,the conditional potential will increase. 2.Equilibrium constant The equilibrium constant indicates the ability of a redox reaction to proceed.If the conditional potential is employed,then we obtain a conditional equilibrium constant. n2OX +n Red2 =n2Red,+n OX2 2022/11/19
Analytical chemistry When a precipitating agent that can precipitate the oxidized form is added, the conditional potential of the couple decreases. If the reduced form precipitates, however, the conditional potential will increase. 2. Equilibrium constant The equilibrium constant indicates the ability of a redox reaction to proceed. If the conditional potential is employed, then we obtain a conditional equilibrium constant. 2022/11/19