Despite Its Name, Acid Rain Doesn T Always Occur in the Form of Rain

ACID RAIN and pH

Despite its name, acid rain doesn’t always occur in the form of rain. In parts of the world with wet weather, there is acid rain, acid snow, and acid fog. In parts of the world with dry weather, there is acid gas and acid dust.

Acid rain is mainly caused by pollutants (like carbon dioxide, carbon monoxide, hazardous air pollutants, etc) being released into the air. Most of the pollutants are from cars - they release harmful smoke into the air, which can cause acid rain. Coal, oil, and gasoline also cause the pollutants.

Acid rain is very harmful to the environment - it can make living things (both in the water and on land) die. Acid rain affects human health. Breathing and lung problems have been linked to acid air pollution. Also, everything that we eat, drink, and breathe has at one time come into contact with acid rain pollutants.

Today’s Lab

All “rainwater” contains some level of acidity. Acidity is measured by pH, which stands for potential of hydrogen. pH is measured on a scale from 0 to 14. The lower the number is on the pH scale, the more acidic; the higher the number, the more basic. Pure water is neutral with a pH of 7.0. When chemicals are mixed with water, the mixture can become either acidic or basic. Normal rainwater has a pH of 5.6. When the pH level of rainwater goes below 5.6, it is considered acid rain.

In today’s activity, you will use a sensitive pH meter and litmus paper to measure the pH of melted snow from our area, as well as tap water, filtered (drinking) water, and ultra pure (laboratory) water. You will then predict and measure the pH of some commonly used household items.

Results Tables

Table 1: Testing the pH of different samples of water

Water Sample / pH
(litmus paper) / pH
(pH meter) / Difference / Acid or base?
Melted snow
Tap water
Filtered (drinking) water
Ultra-Pure (lab) water

Table 2: Testing the pH of compounds that we use everyday

Sample / Predictions / Observations
pH / Acid
or base? / pH
(litmus paper) / pH
(pH meter) / Difference / Acid or base?
Orange Juice
Soda
Rubbing Alcohol