Which Oxide Causes Acid Rain?

Oxidation Process

The primary oxides causing acid rain are sulphur dioxide and nitrogen oxide. Here are the steps explaining the oxidation process of this phenomenon:

• A few natural causes and many human-made ones release sulphur dioxide and nitrogen oxide gases into the atmosphere.

• These gases are quite soluble, travel long distances, and remain in the air for a long time, thanks to the power of wind currents.

• Oxygen, water, and a few chemicals are already present in the air.

• The sulphur and nitrogen gases mix with these elements, resulting in a chemical reaction. Sulphur dioxide becomes sulphuric acid, and nitrogen oxide becomes nitric acid when added to these elements.

◦ SO2 + O2 + H2O = H2SO4 (Sulphur dioxide + Oxygen + Water = Sulphuric Acid)

◦ 4NO2 + O2 + 2H2O = 4HNO3 (Nitric oxide + Oxygen + Water = Nitric Acid)

• Eventually, they fall to the ground in the form of a wet, acidic deposition known as acid rain.

• Acid rain falls to the ground in the form of water, snow, hail, sleet, fog, and other forms.

Source

Now that you know which oxide causes acid rain, you must understand how these oxides are released into the atmosphere, and what are the primary causes of the release of these gases.

The two main sources of these toxic gases are:

• Natural causes –

Natural phenomena like volcanic eruptions release these gases into the atmosphere. However, the occurrences of such natural cases are very few and far between.

• Industrial causes –

Human-made causes are the most important reason for the release of sulphur dioxide and nitrogen oxide into the air. These causes include the following:

◦ Burning of fossil fuels (for example, coal) for generation of electricity in power plants

◦ Cars, commercial vehicles, and trucks emitting sulphur and nitrogen gases into the atmosphere

◦ Toxic gases emitted from oil refineries and factories involved in manufacturing goods

Impact

Acid rain has a lot of harmful effects, and its impact can also be felt at a global level. Although regional air pollution is the root cause of acid rain, it can cause a significant ecological imbalance all over the world due to the following reasons:

• Plants and trees need soil nutrients to grow. However, when soil is exposed to acid rain, these nutrients get dissolved quickly, leaving the plants dry. At a more extensive level, acid rains can damage forests worldwide.

• One of the main functions of plants and trees is to absorb water from the soil for their growth. Acid rains, however, release harmful chemicals like aluminium into the soil. As this chemical seeps in, trees start losing their water-absorption capacity.

• Places with an abundance of mountainous forests are at a greater risk of acid rain. This is because the plants and trees situated at great heights (like fir, pine, deodar, etc.) are in proximity to acidic cloudbursts or acid rain. Exposure to the acidic content of these rains can take away the nutrients from the leaves and branches of these trees, thereby causing extensive damage to these forests.

• Acid rain has a pH level of around 4.4 (highly acidic), whereas the normal pH level of water in lakes, streams, oceans, and other waterbodies is around 7 (neutral). This can severely impact the aquatic life in these waterbodies. The marine ecosystem gets affected when there is considerable risk to the lives of fish, frogs, and other marine species.

• In regions prone to acid rain, you will find that the buildings look dull with the paint layers worn out in many places. The toxic acid content can tear away the paint from buildings, monuments, cars, and statues.

The most important impact of acid rain on the regional and global levels is on one’s health. Exposure to acid rain can cause breathlessness, asthma, bronchitis, lung infections, pneumonia, and other ailments.

FAQs

1. How to prevent the occurrences of acid rain?

Using alternate sources of energy (for example, solar), using vehicles with controlled nitrogen emission, and opting for public transport wherever necessary can control the release of toxic gases into the atmosphere, thereby preventing the occurrences of acid rain.

2. Where is acid rain most common today?

You can find acid rain quite commonly in places like the northeastern parts of the USA, Eastern Europe, and some parts of China and India.