Question

What color is the result (color of the fire) in the combustion of :

A) P & O

B) S & O

C) C & O

D) Mg & O

E) Fe & O

Answer 1

The question asks the flame color when we burn any substance in the presence of oxygen. This test is called as 'Flame Test' and characterstic of certain metals and non-metals. You don't have to supply oxygen as it is abundant in the atmosphere, however, scientists use pure oxygen to note the exact color of the flame.

A) If phosphorus is burnt in oxyxgen, this give a White Flame and produces puffs of smoke clouds. This is due to the formation of mixed oxides of phosophorus (Phosphorus (III) oxide and phosphorus (II) oxide).

B) If Sulphur is burnt in oxygen, it gives a dazzling blue color to the flame. This procecss producess sulphurdioxide and sulphur trioxide mixture, which in the presence of water vapor turn to sulphuric acid.

C) This is the most ususal case as we observe in the kitchen too. The combustion of carbon gives a yellow flame which is close to the color of the flame itself.

D) Magnesium is an interesting one here. Magnesium burns in the presence of oxygen to give Magnesium oxide. IN this process, it produces a while flame which is really bright. This finds use of magnesium in Crackcers.

E) Burning Iron in the presence of oxygen gives a yellow-orange flame. This also produces sparks during the experiment.

The color of the flame also depends on the oxidation state of the metal being used. The answer is provided based on the metal in zero oxidation state.