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Another way to check the health of the environment is to use the pH scale to measure how acidic or basic a substance is. Acids and bases are two special kinds of chemicals. Almost all liquids are either acids or bases to some degree. In this activity, you will learn about the pH scale and why it is important for scientists to measure it in our environment.

The pH Scale

The pH scale measures how acidic or basic something is.

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The pH scale goes from 0 to 14. A reading of 7 is neutral.

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Anything between 0 and 7 is acidic. The closer to 0, the stronger the acid.

Anything between 7 and 14 is basic. Similar to acids, the further from 7, the stronger the base (or alkaline).

A change of the pH level can have drastic effects. For example, normal rain has a pH of about 5.6. If it drops to 4.6, fish will begin to die! Whether life forms live or die can be determined by the pH in their environments. Therefore, pH is a very important measurement. The pH scale is a very important scale to use to monitor our environment.

Let's take a closer look at acids and bases.

An acid is a chemical substance that neutralizes alkalis (a base that dissolves in water). Acids also dissolve some metals and turn litmus red (you will learn more about litmus in the activity below). Typically, acids are corrosive or sour-tasting liquids. Examples include: most citrus fruits, vinegar, carbonic acids in soft drinks, and nitric acid.

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Bases are substances that react with acids and neutralize them (stop the acids from being harmful). They are usually metal oxides, metal hydroxides, metal carbonates, or metal hydrogen carbonates. Many bases are insoluble. This means that they do not dissolve in water. If a base does dissolve in water, we call it an alkali. Examples include: soaps, oven cleaners, ammonia, and baking soda.

Digging Deeper

Click here to go to the Study Jams! website to watch a video. When you have finished watching the video, click on the "close" button in the upper-right hand corner to exit the video. Then, click on the "Test Yourself" button to see how much you know about acids and bases.

So how can acids and bases affect the environment? Acids and bases affect the environment by altering habitats so that they are more favourable to some organisms than others. Acids and bases naturally occur in the environment, and organisms have adapted to the pH of their local habitat over time. If the pH of a habitat changes, some organisms may thrive, others may fail, and others simply flee the habitat.

Another way the environment is affected through acid rain. Acid rain describes any form of precipitation with high levels of nitric and sulfuric acids. Most acid rain falls because of human activities. The biggest culprit is the burning of fossil fuels by coal-burning power plants, factories, and automobiles. Winds may spread these acidic solutions across the atmosphere and over hundreds of miles. When acid rain reaches Earth, it flows across the surface in runoff water, enters water systems, and sinks into the soil, which has many impacts on lakes, streams, and wetlands. This makes waters toxic to crayfish, clams, and other aquatic animals.

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Acid rain also damages forests, especially those at higher elevations. It robs the soil of essential nutrients and releases aluminum in the soil, which makes it hard for trees to take up water. The effects of acid rain leave trees and plants less able to withstand cold temperatures, insects, and disease.