QUESTION

What is acid rain?

MATERIALS

Empty glass jar

Water

Phenol red (available at pool supply stores)

A drinking straw

PROCEDURE

• Fill the jar about half to three-quarters full of cool water.

• Put approximately 20 drops of the phenol red into the water until it turns light red. You can practice this and adjust the amount you add, once you get the hang of the experiment.

• Place the straw into the water and blow so that bubbles form in the water for about 20 seconds. CAUTION: Do not drink the water!

• Check the color of the water. It should be a lighter red than it was before.

• Repeat your 20 seconds of blowing a few more times. Before long, the water should be clear again.

WHAT'S HAPPENING

Phenol red reacts with acids to change color. (You have already learned a little bit about acids in an earlier chapter.) When you blew into the water, the carbon dioxide you blew out (which is not the same as the oxygen you breathe in) reacted with the tap water to form a very weak acid. The more you blew, the more the acid reacted with the phenol red and turned the water clear. Pool cleaners use phenol red to measure how acidic the water is. This tells them what kinds of chemicals to add to maintain the cleanliness of the water.

FOLLOW-UP

What does this have to do with acid rain? When we place too much carbon dioxide into the air, through burning coal, gasoline, or other fossil fuels, it can react with the water in the air (rainwater) to form an acid. When that rain falls to the ground, we get acid in our water and it can become unsafe. It pays to be careful with the gases we exhaust into the air!

KIDS' LAB LESSONS

Winds follow a pattern across the face of the earth, called the Coriolis effect. This pattern tends to produce winds that rotate in a counter-clockwise direction in the Northern Hemisphere and in a clockwise direction in the Southern Hemisphere.

QUESTION How can you tell how fast the wind is blowing?

EXPERIMENT OVERVIEW In this experiment you will build a simple anemometer, a device that measures wind speed. While you won't actually be able to come up with the true wind speed for this project, you'll be able to track different speeds on your own scale and identify which days were the windiest.

SCIENCE CONCEPT Breezes constantly blow across the surface of the earth, and only rarely do they reach the point of being dangerous to people. An anemometer catches the wind in small cups that then rotate. The faster the cups rotate, the faster the wind is blowing.

MATERIALS

Glue

Empty spool of thread or lump of modeling clay

Small block of wood

Pencil

Needle or thin nail

Stopwatch

1 large piece of sturdy cardboard

Scissors

Stapler

Foil muffin cups

1 bright sticker

PROCEDURE

• Glue the spool of thread to the block of wood and wedge the pencil, eraser side up, into it.

• Stick the needle into the eraser.

• Cut two strips out of the piece of cardboard. They should be at least 16 inches long and 2 inches wide.

• With the scissors, cut slits in the bottom of each strip so they fit together to make a cross. Start from the middle of the strip (about 8 inches from either side) and cut upward about 1 inch.

• Glue or staple one muffin cup to each arm of the cross, making sure that each cup points in the same direction. This will ensure that every cup will catch the wind.

• Place the sticker on one of the cups. Make sure it is clearly visible because you will be using it to measure wind speed.

• Place the cross onto the needle so that it rotates freely. If you find that it doesn't rotate, use the needle to make a slightly larger hole until it spins easily.

• Place the anemometer outdoors where it can catch the wind.

• Over the course of several days record the wind speed at different times of day.

Instructions on Measuring Wind Speed Use a stopwatch or a clock that will measure one minute. Count the number of times the cup with the sticker completes one revolution in a minute. Use that number as your wind speed. Each time you record a new measurement, compare it to the previous values.

QUESTIONS FOR THE SCIENTIST

• What was the fastest speed you recorded?_________________________

• What time of day was the windiest? The calmest?_______________________

• Are there places at your house that are windier than others? How could you test this?_____________________________________________________________________

• How do you suppose meteorologists measure the true wind speed?1_____________