Question

What is the colour of flame when ${H_2}S$ burns with${O_2}$?
(A)Green
(B)Blue
(C)Pink
(D)Magenta

Answer 1

Hint: Hydrogen Sulfide $({H_2}S)$ contains 2 atoms of Hydrogen and one Sulfide $({S^{2 - }})$. It is mostly produced by the anaerobic decay (decay which occurs in the absence of oxygen) of organic matter such as plants and animals. It is also obtained in petroleum refineries. It has some other names like hydro sulphuric acid, sewer gas and stink damp. It is a common byproduct in many of the industrial productions like paper, textile, food etc.

Complete answer:
Hydrogen Sulfide $({H_2}S)$ is a hazardous, colorless, extremely flammable gas that burns with a pungent rotten egg smell. In general hydrogen Sulfide acts as a reducing agent especially in the presence of base. Its molar mass is $34.082g/mole$. It is useful for qualitative detection of Inorganic cations like $C{u^{ + 2}},P{b^{ + 2}},H{g^{ + 2}}$.
Hydrogen Sulfide is slightly heavier than air. A mixture of Hydrogen Sulfide and oxygen is highly explosive. Hydrogen Sulfide gas burns in air to produce Sulphur dioxide and water.
$2{H_2}S + 3{O_2} \to 2S{O_2} + 2{H_2}O$
This reaction releases a lot of heat (Exothermic Reaction). It is an example of a double displacement reaction. The burning of Hydrogen Sulfide will take place with a blue flame.
However if the amount of air is limited, the oxidation product is elemental sulphur

So, the correct answer is “Option B”.

Note:
 Hydrogen Sulfide can result in irritation of Eyes, nose and throat. Also it can cause inflammation in the respiratory tract especially in people with Asthma. Low concentrations cause memory loss, tiredness and headaches. High concentrations however cause impairment of the nervous system, unconsciousness and even death.