Burning non-metals in oxygen
Answer Text: Burning non-metals in oxygenRequirements:- Non-metals; deflagrating spoon; gas jar; source of heat;Diagram of apparatus;Procedure:- A piece of sulphur is heated on a deflagrating spoon until it begins to burn;- It is then lowered into a gas jar of oxygen as shown above;- The flame colour is noted;- The gas jar is allowed to cool; some water added to the product(s) in the gas jar and shook well;- Any resultant solution is tested with litmus papers;- Any gases produced are tested by smell and also with litmus papers;- The experiment is then repeated with pure oxygen;- The whole procedure is repeated with other nonmetals such as carbon and phosphorus;Explanations:1. Sulphur.- Burns in oxygen with a blue flame to give a colourless gas with a choking irritating smell;- The gas is sulphur (IV) oxide;Equation:Sulphur + Oxygen → Sulphur (IV) oxide;#S + O_2(g) → SO_2(g)#;- The sulphur (IV) oxide dissolves in water to form sulphurous acid, which turns litmus rd;#SO_2(g) + H_2O(l) → H_2SO_3(l)#;2. Carbon- Glows red to give a colourless gas that forms a white precipitate in lime water;- The gas is Carbon (IV) oxide;Equation:Carbon + Oxygen → Carbon (IV) oxide;#C + O_2(g) → CO_2(g)#;- The Carbon (IV) oxide dissolves in water to form weak carbonic acid, which turns litmus rd;#CO_2(g) + H_2O(l) → H_2CO_3(l)#;Note:- In limited oxygen the carbon undergoes partial oxidation forming carbon (II) oxide;Equation:#2C(s) + O_2(g) → 2CO(g)#3. Phosphorus.- Burns in oxygen with a white flame to give dense white fumes;- The white fumes are either phosphorus (V) oxide or phosphorus (III) oxide;- Both solids // fumes dissolve in water to form phosphoric acid;Equations:With limited supply of oxygen:Phosphorus + Oxygen → Phosphorus (III) oxide;#P_4(s) + 3O_2(g) →2P_2O_3(g)#;With excess oxygen.Phosphorus + Oxygen → Phosphorus (V) oxide;#P_4(s) + 5O_2(g) →P_2O_10(g)#;