Question

Ethanol and sodium react to each other and produce a gas which burns in blue flame. Identify them and mention the reaction.

Answer 1

Hint : When a small piece of sodium is dropped into ethanol, it will react steadily and give off bubbles of hydrogen gas and also leave a colorless solution of sodium ethoxide. Hydrogen gas formed is flammable i.e. it can be easily set on fire.

Complete Step By Step Answer:
When ethanol is applied to a small piece of sodium wire, it reacts slowly to give hydrogen gas bubbles and also it leaves a colorless sodium ethoxide solution. When ethanol is dumped onto a small piece of sodium, it reacts slowly to produce hydrogen gas bubbles and also leaves a colorless sodium ethoxide solution. The anion component here is an alkoxide. The reaction is as follows:
$2C{H_3}C{H_2}OH + 2Na \to 2C{H_3}C{H_2}{O^ - } + 2N{a^ + } + {H_2}(g)$
If this solution is evaporated to dryness, then sodium ethoxide is left behind in the form of a white solid. The hydrogen gas released burns with a pale blue flame which is nearly invisible in daylight. If there are impurities in the air like dust or sodium, the flame may appear yellow in color. A blue colored flame can be observed when the amount of soot decreases.

Note :
When hydrogen is burning, it undergoes a chemical reaction where it combines with oxygen and forms water releasing a lot of energy in the form of heat. The heat released causes gases to expand such that the gas molecules break the sound barrier. So, a pop sound appears on burning of hydrogen in air.