Acid Rain

You have probably heard this term before, and like most people, you might have been concerned that a harmful substance, such as an acid, might be falling on your head, carefully concealed in rain drops. You might also worry about the effects of such rain on your animals and your plants. You are right to worry.

Let us first explain what acid rain is.

 

Car batteries have acid. The acid is so strong, it would causes severe burns if it contacted your skin

What Is Acid Rain?

You cannot tell the difference between acid rain and normal rain with your five senses.  You need a chemical means to measure how acid the rain drops are. The unit of measure for acidity is called pH. This measurement scale is based on logarithms, because the range of possible concentrations of acid is enormous, ranging from none to a whole lot of acid. The scale also runs in the other direction, to include measures for chemicals that have negative acidity (more properly called basic compounds). The pH scale ranges from 0 to 14, with the value of 7 being neutral (neither acid or base).  Numbers from 0 to 7 are acid values and from 7 to 14 are basic values. You want your rain water to be near neutral (near a pH of 7). Actually, normal rain tends to have a pH value of about 5.5. Where do you suppose that acid came from?

What Causes Acid Rain?

Environmental scientists have found that the main causes of acid rain come from two chemical compounds: sulfur dioxide (SO2) and nitrogen oxides (NOx). These compounds get into the air and dissolve into the water in the air, which carry the compounds back to earth when it rains. But how do these compounds get into the air in the first place?
Burning fossil fuel supplies most of the SO2 and NOx. To summarize;
  • Power plants, automobiles, and other sources burn fossil fuels
  • SO2 and NOx are released into the air
  • These compounds dissolve in and react with water in the air, making the water acid
  • Rain, sleet, and snow carry the acid back to earth

 

What happens next?

 


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