Question

In a test, Rashi has to write the chemical equation for the formation of hydrochloric acid. She wrote

$H_2+2Cl\to 2HCl$

The teacher marked the answer wrong. Why is it so?

• A. The equation is not balanced.
• B. Hydrogen and chlorine do not react to form hydrochloric acid.
• C. In this 2 atoms of chlorine were used insteadof1 molecule of chlorine.
• D. In this 2 molecule of chlorine was used instead of 2 atoms of chlorine.

Answer 1

The correct option is C

In this 2 atoms of chlorine were used insteadof1 molecule of chlorine.

The correct equation should be:

$H_2+C{l}_2\to 2HCl$

2Cl means 2 atoms of chlorine while $C{l}_2$ means 1 molecule of chlorine formed from 2 atoms.

When we write the chemical equation we need to use the elements in their natural form. In its natural, chlorine exists as $C{l}_2$ and not Cl.