Chem! Concerning metal reactivity -- 10 pts
1. Why do metals react with water to form metal hydroxide but reacts with steam to form metal oxide? They are of the same constituents.
eg. Mg+2H2O(l) --> Mg(OH)2 +H2
Mg+ H2O(g)--> MgO + H2
So that means... when steam reacts with metal, a metal hydroxide is formed first, but then the water molecule is boiled away, leaving the metal oxide there? Is this correct?
- Audrey HepburnLv 71 十年前最愛解答
When metals react with water
Mg(s) + 2H2O(l) → Mg(OH)2(aq) + H2(g)
Metal hydroxide is formed
When metals react with steam
Mg(s) + H2O(g) → MgO(s) + H2(g)
Metal oxide is formed instead of metal hydroxide.
Please note that steam is usually over 100℃, which is the boiling point of water.
In magnesium hydroxide, a water molecule exist.
i.e. In Mg(OH)2, you may find a H2O molecule in it.
So, when steam reacts with metal,
The water molecule is boiled away.
That’s why metal oxide is formed instead of metal hydroxide.
Note that: MgO + H2O → Mg(OH)2資料來源： Myself~~~