How will you prepare hydrochloric acid in laboratory?
Describe briefly the method employed to dissolve hydrogen chloride gas in water as it is prepared. What is the purpose of funnel while preparing hydrochloric acid from HCl gas?
Sodium chloride and sulphuric acid are used as the main reactants for producing hydrogen chloride gas in the laboratory.
The reaction takes place as follows:
NaCl(s) + H2SO4(aq) → NaHSO4(s) + HCl(g)
Sodium chloride Sulphuric acid Sodium hydrogen Hydrogen chloride
"Inverted Funnel Arrangement" is used to dissolve hydrogen chloride gas in water. An inverted funnel is connected to the HCl gas supply and placed in a beaker in such a way that the rim of the funnel just touches the upper surface of water inside the beaker. The mouth of the funnel is filled with HCl gas, which starts dissolving in water, creating a low pressure region. Due to back suction, the water level in the funnel rises. The funnel’s rim loses contact with water, letting in the outside air through the gap, so as to balance out the pressure. The gravitational force pulls the solution back into the beaker. As the level of water in the funnel falls, it drops back to its original position.
The entire process is repeated till the water inside the beaker becomes saturated with HCl gas.
A funnel is used in the preparation of hydrochloric acid as it provides a large surface area for the dissolution of hydrogen chloride vapours.