Chemistry related

Question

Incandescent carbon particles cause a gas flame to be yellow. To obtain a hotter blue flame you should

(A)open the air holes.

(B)close the air holes.

(C)open the needle valve at the base of the burner to increase the gas supply.

(D)partly close the supply valve at the gas jet.

(E)place a beaker of cold water over the flame to

cool the flame.

Could you explain which option you chose and why?

Answer 1

The correct answer is (A) open the air holes.

The yellow color of the gas flame is caused by the incomplete combustion of the gas, which produces incandescent carbon particles that emit yellow light. To obtain a hotter blue flame, the combustion process must be made more complete by increasing the amount of oxygen that is available to react with the gas.

By opening the air holes, more air is allowed to mix with the gas, which increases the amount of oxygen available for combustion. This results in a hotter flame that burns more efficiently, producing a blue color.

Option (B) closing the air holes would reduce the amount of oxygen available for combustion, leading to a less efficient and cooler flame.

Option (C) opening the needle valve at the base of the burner would increase the gas supply, but without sufficient oxygen, the combustion would still be incomplete, resulting in a yellow flame.

Option (D) partly closing the supply valve at the gas jet would reduce the amount of gas flowing to the burner, leading to a weaker flame, but again, without sufficient oxygen, the combustion would still be incomplete.

Option (E) placing a beaker of cold water over the flame would cool the flame, but it would not improve the combustion process or make the flame hotter.