[abcc]

When we do the determination of Fe(III) in food by spectrophotometry, the sample & standard solutions are always in acidic medium(e.g. HCl ). WHY a low pH is needed
anyone has done this experiment before?
THX

[Borek]

What is Fe(OH)₃ solubility?

[abcc]

What is Fe(OH)₃ solubility?

i know Fe(OH)3 is temperature and pH dependent
UMM...in acidic condition, Fe(OH)3 will be precipitated out
but....what you mean in my experiement??
in low pH , Fe3+ with aqueous(H2O) = Fe(OH)3

[mdlhvn]

It's total reverse. Low pH prevents Fe3+ from reacting with water to form Fe(OH)3. We can use the solubility product to explain:

Solubility product (sp)=[Fe₃₊][OH-]³. Sp is only dependent on temperature, and all your experiments occur mostly at room temperature, then Sp remains the same. So at low pH, also low concentration of OH, we will have high concentration of Fe3+. It make possible to determine exactly Fe3+.

[abcc]

It's total reverse. Low pH prevents Fe3+ from reacting with water to form Fe(OH)3. We can use the solubility product to explain:

Solubility product (sp)=[Fe₃₊][OH-]³. Sp is only dependent on temperature, and all your experiments occur mostly at room temperature, then Sp remains the same. So at low pH, also low concentration of OH, we will have high concentration of Fe3+. It make possible to determine exactly Fe3+.

OOOOOOOO
great!!!!
thx
pretty help