Lesson 3 - What would happen if you drank a glass of acid?

Activity: Acid Test

The purple cabbage water only turned slightly pink. Any suggestions?

Soaking the cabbage overnight should have turned the liquid purple, even in cold water. If your liquid is only slightly pink, here are some things to consider:

• Temperature of the water: if cold water doesn’t work, try using warm or hot water. This will help speed up the reaction.
• Freshness of the cabbage: the fresher the cabbage, the deeper the purple indicator color will be.
• Acidity of the water: the tap water you are using may be slightly acidic. Try using water from a different source, such as home or school, or bottled water.

Pink water will most likely still work for the activity. You can test it by putting a teaspoon of pink water in two separate cups. Add a drop of acid such as vinegar, orange juice, or lemon juice to one cup and add a pinch of baking soda (not baking powder) to the other. If you notice a change of color in either of the cups, this shows that you have successfully made an acid-base indicator, which is what you need for the experiment.

Alternatively, you can substitute 7 ounces of dried black beans for the purple cabbage.

Can I use water from a can of kidney beans for the indicator liquid?

We haven't tested this experiment with another type of beans, so we can't say definitively if it will be as effective. However, you can do a simple experiment to see whether the type of beans you have will work! Here are the steps:

1. Pour a small amount of bean water in two separate bowls (white or clear if possible.)
2. Add some baking soda to one bowl and some vinegar to the other. If there is a dramatic color difference in the bean water, it will work for the experiment.

For the citric acid, I have lemon juice concentrate (with water.) What ratio would you recommend?

You’ll need something with the acidity of pure lemon juice. If the lemon juice concentrate is 100% pure lemon juice, you can use it as is, otherwise you’ll need to use a different acid source like vinegar or orange juice.