Science Library - free educational site

Acid Rain

Acid rain is still a major cause of damage to ecosystems, water resources, agriculture and infrastructure

Every year, a giant brown cloud of pollution grows and moves across South-East Asia. In this cloud are smoke from deforestation, but also huge quantities of SO2 and NO2 from the burning of fossil fuels. These chemicals lead to the formation of sulphuric and nitric acid in clouds, which do not respect national boundaries. The acid rain they produce can fall far from the source of the pollution, and cause major damage to ecosystems, water resources, agriculture and infrastructure. The economic costs are far from insignificant.

There is a long-established link between poor pollution control and economic and environmental impacts. But what are developed and developing nations doing in their struggle to reduce this perennial, transboundary problem?

Andrew Bone has been investigating the situation concerning national policies and international law regarding transboundary pollution, and asks the question: Are we doing enough?

Unusually acidic precipitation, the result of air pollution. Acid rain is a transboundary problem, with clouds carrying the acid to other countries, and therefore the subject of international and bilateral agreements.

The emissions of SO2 and NO2 leads to the formation of sulphuric and nitrous acid in clouds. Acid rain can fall far from the source of the pollution, and cause major damage to ecosystems, water resources, agriculture and infrastructure.

The equations are:

Sulphuric Acid

Sulphuric acid forms from SO2 gaseous emissions, from coal-fired power stations primarily, which reacts with atmospheric oxygen to form sulphuric trioxide, SO3:

2SO2 + O2 → 2SO3

This gaseous sulphuric trioxide is carried to clouds, where it reacts with water droplets to form aqueous sulphuric acid, H2SO4:

SO3 + H2O → H2SO4

In mist, the sulphur dioxide can react directly with water:

SO2 + H2O → H2SO3

2H2SO3 + O2 → 2H2SO4

Nitric Acid

Nitric acid forms from NO2 gaseous emissions, from petrol and diesel vehicle exhausts primarily, which react with atmospheric water to form nitric acid, HNO3:

2NO2 + H2O → HNO2 + HNO3

N2O4 can also form nitric acid:

N2O4 + H2O → HNO2 + HNO3

Article by Andrew Bone, December 31, 2015

News Articles

Pollution News

Environment News

Other News

Latest Item on Science Library

The most recent article is:


View this item in the topic:

Vectors and Trigonometry

and many more articles in the subject:

Subject of the Week


Mathematics is the most important tool of science. The quest to understand the world and the universe using mathematics is as old as civilisation, and has led to the science and technology of today. Learn about the techniques and history of mathematics on


Test your knowledge!

Question: How many sugar cubes of side length 1cm would fit inside a crate the shape of a cube with side length 1 metre?

Go to the article about: Shapes

Vitruvian Boy

Quote of the day...

All knowledge - past, present, and future - can be derived from data by a single, universal learning algorithm.

ZumGuy Internet Promotions

Renewable energy media services