about reactions and the colour change

2007-03-30 5:14 am

Please write the equation and the colour change when Iron(lll)chloride is addedinto the following chemicals:
1.KCNS
2.KNO3
3.C6H60/PhOH
4.CH3COONa
5.Na2S
6.K3Fe(CN)6
7.NaOH

更新1:

2.AgNo3

更新2:

4.醋酸(Na)

回答 (1)

Uncle Michael

2007-03-30 8:21 am

✔ 最佳答案

1.
The colourless solution of KCNS turns deep red.
Fe2+(aq) + CNS-(aq) = [FeCNS]2+(aq)
(reversible reaction)

2.
There is no reaction.

3.
The colourless solution of phenol turns violet.
Fe3+(aq) + 3C6H5OH(aq) → [Fe(OC6H5)3](aq) + 6H+(aq)

4.
There is no reaction.

5.
A black precipitate is formed.
2Fe3+(aq) + 3S2-(aq) → Fe2S3(s)

6.
No information about the reaction between FeCl3 and K3[Fe(CN)6] is found.
However, FeCl3 reacts with K4[Fe(CN)6] to give a deep blue precipitate (called Prussian blue).
Fe3+(aq) + [Fe(CN)6]4-(aq) → Fe4[Fe(CN)6]3(s)

7.
A reddish brown precipitate is formed.
Fe3+(aq) + 3OH-(aq) → Fe(OH)3(s)

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