關於Oxidation and reduction的化學問題

1.
The answer is D.

(1) incorrect
Dilute nitric acid is an oxidizing agent, which can react with copper to give nitrogen monoxide gas.
3Cu(s) + 8H+(aq) + 2NO3-(aq) → 3Cu2+(aq) + 4H2O(l) + 2NO(g)

(2) correct
All acids can turn litmus solution red.

(3) correct
All acids can reacts with sodium carbonate to give carbon dioxide gas.

2.
In CE level, the answer is A.

A. The oxidation number of S is -2.
FeS is an ionic compound which contains Fe2+ and S2-.

B. The oxidation number of S is +6.
(NH4)2SO4 is an ionic compound which contains NH4+ and SO42-.
In SO42-, sum of the oxidation number is equal to the charge carried by the ion.
(oxidation number of S) + 4(-2) = -2
Hence, oxidation number of S = +6

C. The oxidation number of S is +4.
(oxidation number of S) + 2(-2) = 0
Hence, oxidation number of S = +4

D. In CE level, the oxidation number of S is
Na2S2O3 is an ionic compound which contains Na+ and S2O32-.
In S2O32-, 2(oxidation number of S) + 3(-2) = -2
Hence, oxidation number of S = +2
However, in AL level, the two S atoms in S2O32- have different oxidation number.
The two different oxidation numbers are 0 and +4.
=

2009-03-08 15:54:24 補充：
D. In CE level, the oxidation number of S is +2.