What Are Reversible Reactions? | Reactions | Chemistry | FuseSchool

in this lesson we will learn about

reversible reactions when we fry an egg

it is impossible to on fry it a lot of

reactions work in the same way once it

is done it is irreversible a good

example is the combustion of magnesium

to form magnesium oxide reversible

reactions are reactions where formed

products can revert or go back to their

original reactants since the reaction

can proceed in either direction we use

this reaction arrow to represent

reversibility an example of a reversible

reaction is the thermal decomposition of

ammonium chloride to form ammonia and

hydrogen chloride place ammonium

chloride in a boiling tube and heat

using a Bunsen burner ensure that this

is conducted in a fume cupboard as

ammonia and hydrogen chloride are both

corrosive gases if we hold red litmus

paper at the mouth of the boiling tube

it turns blue which confirms the

presence of ammonia blue litmus paper

turns red which confirms the presence of

hydrogen chloride remove the boiling

tube from the heat and let cool have a

look near the mouth of the boiling tube

you will see that there are white

crystals these are ammonium chloride

crystals so what has happened here

ammonium chloride has thermally

decomposed to ammonia and hydrogen

chloride the formed ammonia and hydrogen

chloride have reacted to produce

ammonium chloride therefore this is a

reversible reaction why is the thermal

decomposition of ammonium chloride

sometimes incorrectly called a

sublimation reaction please pause the

lesson to think about this and resume

when you are done

here is a hint think about phase changes

and what happens to a substance during a

phase change when a substance goes from

the solid phase to a gas phase it is

said that it has sublimed this phase

change is not a reaction as the

substance itself has not changed in our

example solid ammonium chloride did not

form a gaseous ammonium chloride but

rather it decomposed under heat to form

ammonia and hydrogen chloride therefore

it is not a sublimation reaction