Science Activity: Nice Spice

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This activity uses a common spice and a few other kitchen items to explore chemical reactions. You'll have fun observing these reactions, since some of them may cause color changes.

1. Get Ready

1/4 teaspoon turmeric (a food-coloring powder/spice usually found in the spice section of the supermarket)
1/4 cup rubbing alcohol
1/4 cup white vinegar
1/4 cup water
1/4 cup water plus 1 teaspoon baking soda (mixed together)
1/4 cup glass-cleaning liquid
Six small, clean jars (about the size of baby food jars)
Flour strips cut from a  white coffee filter, each 1 inch (about 2 1/2 centimeters) wide by 2 inches (about 5 centimeters) long
Masking tape and marker

2. Do and Wonder

Use small pieces of masking tape to put labels on the jars. Then use the marker to label the jars as follows: "Soaked Strips," "Alcohol," "Vinegar," "Water," "Water plus Baking Soda," and "Glass Cleaner."

Put the "Soaked Strips" jar aside for now. Pour one of the liquids into each of the remaining jars, following the labels.

Dissolve the turmeric in the alcohol, and let it stand for a few minutes. Change the label on the jar to read "Turmeric plus Alcohol."

Hold each strip of coffee filter by one end, and soak half of it in the turmeric and alcohol solution. Store the four strips in the jar labeled "Soaked Strips."

Make a chart to write down what you will observe later in the activity, when  you will dip each soaked paper strip in one of the remaining liquids. Also write down your predictions for what you think will happen with each liquid.

Dip one strip in each liquid, and write down what you observe on the chart.

What do you think will happen when you spray the strip with glass cleaner? Try it.

3. Think and write

Turmeric is an indicator, which means that it changes color when it touches certain substances. Turmeric is usually used to give rice and other foods a yellowish color. If you wanted to create a yellow-colored salad dressing using vinegar, would adding turmeric make this happen? Explain your thinking in a short paragraph.

Explanation

Adding turmeric to a substance indicates whether a chemical called a base is present. The yellow turmeric-soaked strip turns reddish when placed in a base. We see the color change because the color of light reflecting from the molecules changes when the molecules do. This happens when the turmeric and base react. Baking soda in water is a weak base. Common glass-cleaning spray contains ammonium hydroxide, which is also a base. Turmeric does not react with acids.

Safety Hints

Be sure to keep the liquids away from your eyes. Also try not to breathe in any of them.

Rinse out the jars thoroughly before using them.

Wash your hands thoroughly when you're done.