ACIDS AND ALKALISAcid rain

Acid rain

- Natural acid rain- CO₂ in the air dissolves in the water in

clouds forming Carbonic acid (weak acid)

- When this weak acid falls on limestone a reaction occurs and some of the limestone is washed away.

Cracks called grikes appear

- In most of the places where most of the limestone surface is dissolved away, pinnacles of rock appear.

- The acid rain sinks into the rock and forms underground streams.

- The water passing in the underground streams dissolves more rock and forming caves.

- As the caves grow bigger the walls become weaker and collapse forming a gorge.

Air pollution and acid rain

- Fuels such as coals and oil contain sulphur.

- When the fuel is burnt it reacts with the oxygen in the air to form sulphur dioxide.

- The sulphur dioxide reacts with the oxygen and water in the air to form sulphuric acid.

- Factories and cars also produce nitrogen oxides which produces nitric acid.

The effect of acid rain

- When acid rain reaches the ground it dissolves some of the minerals in the soil and carries them away. This is called leaching.

- Some of these minerals are needed for healthy growth of the plants