Introduction
Acids and bases are the commonly used words in day to day life. We all use some of the acids and bases daily. For example, fruits like lemon and orange contain citric acid and we use it regularly. Our body contains some amount of acids like hydrochloric acid in the stomach, which helps in the digestion of food. Similarly, some of the bases which we come across in our day to day life are the soaps that we use at home are basic in nature. These are slippery in nature and hence widely used as cleansing agents.
How do we define them?
Acids are derived from the Latin word acidus which means sour. Hence all the sour substances contain acid. Acids are corrosive in nature. Bases are the substances which are bitter in taste. Bases feel soapy on touching them. These can be either natural or synthetic.
Some of the common naturally occurring acids and bases are mentioned in the table below
Acids
| Name | Found in |
| Acetic acid | Vinegar |
| Formic acid | Ant’s sting |
| Citric acid | Citrus fruits |
Bases
| Name | Found in |
| Calcium hydroxide | Lime water |
| Magnesium hydroxide | Milk of Magnesia |
| Sodium hydroxide | Soap |
Basic Properties
| Properties | Acid | Base |
| Taste | Sour | Bitter |
| pH value | Less than 7 | More than 7 |
| Litmus paper | Blue to red | Red to blue |
| Corrosive | Highly corrosive in nature | Only strong bases are corrosive in nature |
| Conduction of electricity | Conducts electricity in all states | Conducts electricity only in an aqueous state |
Acid Rain
Acid rain as the name suggests the rain contains acid. In simple words, it is the precipitation of acid in the form of rain. When the atmospheric pollutants like oxides of nitrogen and sulfur when gets mixed with rain and it comes down to earth’s surface in the form of acid rain.
Causes
Nature and man, both play a vital role in the formation and causes of acid rain. But man contributes majorly in this. The gases like sulfur dioxide and nitrogen oxide produced on combustion of fossil fuels also join its hands in the formation of acid rain.
Natural Source:
The volcanic eruption has a major hand in the natural cause of acid rain. Volcanoes produce a huge amount of hot poisonous gases that get mixed with air and moisture present in the atmosphere. Then, during the rainy season, all these gases present in the atmosphere come down along with the rain and become the cause of acid rain.
The lighting that strikes during rain produces oxides of nitrogen and mixing with water molecules forms acid rain.
Man-made source:
Man plays a vital role in destroying nature. The air pollution caused due to automobiles, industries, and power generating stations contributes to the formation of the oxides of sulfur and nitrogen. These oxides, when precipitated and combines with water molecules, forms acid rain.
Harmful effects on the environment
- It has adversely affected aquatic lifeforms. The species living in water will have to face the pH value below 7 and hence lose their life due to acidic water.
- The soil has lost its fertility due to the acidic substances present in the water content.
- The historical monuments, statues are all damaged due to the acid droplets falling on them.