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Reaction of metals with steam.

Answer Text:
Magnesium and other metals.
- Magnesium reacts with atmospheric oxygen to form magnesium oxide that coat the metal surface;
- Thus before reacting it with water this oxide layer has to be removed e.g. by polishing metal surface using sand paper;
- Reaction between magnesium and cold water is generally very slow; with very slow evolution of hydrogen gas;
- Zinc and iron metals do not react with cold water;
Reaction of metals with steam.
Note:
- Metals that react with cold water would react very explosively with steam and thus their reactions with steam should not be attempted in the laboratory;
- However some metals which react only sparingly with cold water or do not react with cold water at all react with steam to produce respective metal oxide and hydrogen gas;
1. Magnesium
Procedure:
- A small amount of wet sand is put at the bottom of a boiling tube;
- A small piece of magnesium ribbon is cleaned and put in the middle of the combustion tube;
- The magnesium ribbon is heated strongly then the wet sand is warmed gently;
- The delivery tube is removed before heating stops; and the gas produced is tested using a burning splint;
Diagram of apparatus:

Observations and
explanations.
- Magnesium burns with a bright blinding flame;
- Grey solid (magnesium) forms a white solid; due to formation of magnesium oxide;
- Evolution of a colourless gas that burns with a pop sound; confirming it is hydrogen;
Reaction equation.
Magnesium + Steam → Magnesium oxide + Hydrogen gas;
#Mg(s) + H_2O(g) → MgO(s) + H_2(g)#;