Hydrogen Chloride

Who first prepared hydrochloric acid and when?

Glauber in 1648 by heating common salt with concentrated sulphuric acid.

Who named hydrochloric acid as muriatic acid?

Lavoisier

Who gave the name hydrochloric acid?

Davy in 1810

Where does hydrogen chloride gas occur naturally?

In free state in volcanic emissions

Where is hydrochloric acid found in the human body?

In gastric juice of mammals (0.2 - 0.4%) aiding digestion

What are the reactants in the lab preparation of hydrogen chloride?

Sodium chloride (NaCl) and concentrated sulphuric acid (H2SO4)

Write the chemical equation for lab preparation of HCl gas.

NaCl + H2SO4 → NaHSO4 + HCl↑

Why is temperature kept below 200°C during HCl preparation?

Because the reaction is reversible and to allow slow escape of HCl gas

Why is NaCl preferred in HCl preparation?

Because it is cheap and readily available

Why is concentrated nitric acid not used in HCl preparation?

It is volatile

Why can't HCl be collected over water?

Because it is highly soluble in water

How is HCl gas collected?

By upward displacement of air (downward delivery method)

Why is HCl gas dried with conc. sulphuric acid?

Because other drying agents react with HCl

Write the reaction of P2O5 with HCl.

2P2O5 + 3HCl → POCl3 + 3HPO3

Write the reaction of CaO with HCl.

CaO + 2HCl → CaCl2 + H2O

What is formed when HCl dissolves in water?

Hydrochloric acid

Why does HCl act as an acid only in water?

Due to ionisation from its polar nature forming H3O+ and Cl−

Write the ionisation equation of HCl in water.

HCl + H2O → H3O+ + Cl−

Does dry or liquefied HCl show acidic properties?

No

How is hydrochloric acid prepared in the lab?

By passing HCl gas into water until no more is absorbed

What concentration is typically obtained in lab-prepared HCl?

About 36% hydrogen chloride by mass

What is the purpose of the funnel in the lab preparation of HCl acid?

To prevent back suction and increase surface area for absorption

What is a constant boiling mixture or azeotrope?

A solution that boils without changing its composition

At what temperature does HCl form an azeotrope?

110°C

What are the physical properties of hydrochloric acid?

Colourless