Sau khi trộn: `C_{Fe^{3+}}=10^{-4}(M) ;C_{NaF}=0, 02M;C_{KSCN}=0,01M`

Bảo toàn nồng độ đầu:

`C_{Fe^{3+}}=[Fe^{3+}]+[FeOH^{2+}]+Fe(SCN)_i^{3-i} + +FeF_i^{3-i}`

`=> 10^{-4}=[Fe^{3+}].(1+10^{-2, 17}/{0, 03}+10^{3, 03}.0, 01+10^{4, 187}.0, 01^2+10^{5, 585}.0, 01^3+10^{6, 381}.10^4+10^{6, 4}.0, 01^{5}+10^{5,72}[F^-]+10^{10,13}.[F^-]^2+10^{13,4}.[F^-]^3)` 

`=> [Fe^{3+}]=(10^{-4})/(13,888+10^{5,72}[F^-]+10^{10,13}.[F^-]^{2}+10^{13,4}.[F^-]^{3})    (1)` 

`C_{NaF}=[F^-]+[HF]+[FeF^{2+}]+2[FeF_2^+]+3[FeF_3]`

`=> 0,02=[F^-]+(10^{-2, 17}) /(0, 03).[F^-]+[Fe^{3+}].(10^{5,72}[F^-]+2.10^{10,13}.[F^-]^2+3.10^{13,4}.[F^-]^3)`

Thay `(1)` vào ta được:

`[F^-]=4, 38.10^{-4}(M) `

Thay `[F^-]` vào `(1) :[Fe^{3+}]=1, 907.10^{-8}(M)` 

`[Fe(SCN) ^{2+}]=1,907.10^{-8}.0, 01.10^{3, 03}=2,04.10^{-7}(M)` 

`[Fe(SCN)_2 ^+]=1,907.10^{-8}.0, 01^{2}.10^{4, 187}=2,93.10^{-8}(M) `

`Fe(SCN) _3]=1,907.10^{-8}.0, 01^{3}.10^{5, 585}=7,33.10^{-9}(M)`

`[Fe(SCN) _4^{-}]=1,907.10^{-8}.0, 01^{4}.10^{-6, 381}=4,585.10^{-10}(M) `

`[Fe(SCN) _5^{2-}]=1,907.10^{-8}.0, 01^{5}.10^{6, 4}=4,79.10^{-12}(M) `

`[FeF^{2+}]=1,907.10^{-8}.4,38.10^{-4}.10^{5, 72}=4,38.10^{-6}`

`[FeF_2^-]=1,907.10^{-8}.(4,38.10^{-4})^{2}.10^{10, 18}=5,54.10^{-5}(M) `

`[FeF_3]=1,907.10^{-8}.(4,38.10^{-4})^{3}.10^{13, 4}=4,025.10^{-5}(M) `

`[FeOH^{2+}]=1, 907.10^{-8}.(10^{-2, 17}/(0, 03) =4, 3.10^{-9}(M) `

`[OH^-]=(10^{-14}) /(0, 03) =3, 33.10^{-13}(M) `

`[HF]=(0,03.4,38.10^{-4}) /(10^{-3,17}) =0, 0194(M)` 

`b) [Fe(SCN) _i^{(3-i)+}]=12,888.1,907.10^{-8}=2,46.10^{-7}<10^{-5}=>` dung dịch ko màu