Picking up garbage, recycling or planting trees are all typical Earth Day activities. Here is a fun and interactive home science experiment to help your kids understand their community as part of the global environment.

With a simple home science experiment you can test the acidic level of the rain that falls in your community. You probably have most of the needed materials in your own home

Begin by talking to your children about what contributes to acid rain. One of the main causes of acid rain is sulfur dioxide. Natural sources that emit this gas are volcanoes and rotting vegetation. However, the burning of fossil fuels, such as coal and oil, produce approximately half of the emissions of this gas around the world. Remember to tell your kids that although these acids are normally too weak to harm humans, over time these acids can affect plants as well as other materials.

How do you know if your rain is acidic? Acidity is measured on a pH scale with a range of 0 to 14. Substances with a pH of 7 are described as neutral. A pH lower than 7 means the substance is an acid and higher than 7 means the substance is a base or alkali. Out of curiosity, your kids may want to know that pH stands for potential hydrogen. Acid rain is defined as any rainfall that has an acidity level or pH value of lower than 5.6. To test your rain for acidity you will need a pH indicator.

Preparing for your experiment:

• Collect rainwater in a clean container such as a pail or 2-litre plastic pop bottle with the top cut off.

• Make your pH indicator as instructed below.

• Ensure you have all the materials listed below.

Materials

• Sliced red cabbage

• 1 quart of water

• 1 large pan or microwave casserole dish

• stove, microwave or hotplate

• 3 glass cups (preferably clear)

• white vinegar

• ammonia or baking soda

• 1 clean 2-litre pop bottle or clean pail

• rain water

• a pen and paper
   

A Natural pH indicator you can use:
Red cabbage juice contains a chemical that turns from its natural deep purple color to red in acids and blue in bases. Parents can make it at home following these instructions carefully: Boil cabbage in a covered pan for 30 minutes or microwave for 10 minutes ensuring that the water doesn't boil away. Let cool before removing the cabbage.

Experiment instructions:

1. Pour the cabbage juice into the three clean glasses until they are about 1/4 full.
2. Add 1/2 teaspoon of vinegar to one glass and stir with a clean spoon.
3. Add 1/2 teaspoon of ammonia or baking soda to second cup, stir with a clean spoon.
4. Add about a teaspoon of the rainwater to third cup, stir with a clean spoon.
5. Observe and record your results

The first cup should change from deep purple to red, indicating that vinegar is an acid. The second cup should turn to blue indicating the ammonia or baking soda is a base. What happened to the third cup? Did it change red (acid) or blue (base) or stay the same (neutral)? (Your child may want to test other common household substances such as clear soda pop or different fruits).