ce chem

1.
Ammonia gas is a weak reducing agent. All the reactants and products involved are molecular. Therefore, it is impossible to write ionic equations for the reactions. There are three common examples for ammonia acting as a reducing agent :

Example 1 : Ammonia gas burns in pure oxygen with a yellow flame to give nitrogen gas. (Ammonia does not burn in air)
4NH3(g) + 3O2(g) → 2N2(g) + 6H2O(g)

Example 2 : Ammonia gas can be oxidized by red hot copper(II) oxide to give nitrogen gas.
3CuO(s) + 2NH3(g) → 3Cu(s) + N2(g) + 3H2O(g)

Example 3 : In the presence of platinum catalyst, ammonia can be oxidized by oxygen in air to give nitrogen monoxide gas. The reaction is called catalytic oxidation of ammonia.
4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)

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2.
The most abundant metallic element in the Earth is iron, but the most abundant metallic element in the Earth crust is aluminium.

2008-04-02 22:02:42 補充：
Oxidation numbers :
N in NH3 = -3
N in N2 = 0
N in NO = +2

1) I don't think ammonia is a reducing agent....
2) Al

1) 首先, AMMONIA 加左水, 會係 NH3 + H2O= NH4+ + OH-

2) MOST ABOUNDANT METALLIC ELEMENT IN THE "earth"
係鐵

不過 most abundant metallic element in the earth CRUST係ALUMINIUM