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Acid Rain Experiments – Experiment 7 – Observing the Influence of Acid Rain on Plant Growth

Acid rain most often damages plants by washing away nutrients and by poisoning the plants with toxic metals. It can, however, have direct effects on plants as well. In this experiment you will observe one of the direct effects of acid water on plant growth. The experiment will take about two weeks.

Materials

Instructions

  1. Pour 1 teaspoon of vinegar into 2 cups of distilled water, stir well, and check the pH with either pH paper or a garden soil pH testing kit. The pH of the vinegar/water mixture should be about 4. If it is below pH 4, add a sprinkle of baking soda, or a drop of ammonia, stir well, and recheck the pH. If it is above pH 4, add a drop or two of vinegar and again recheck the pH.
  2. Measure the pH of the distilled water using either pH paper or a garden soil pH testing kit. If the pH is below 7, add about 1/8 teaspoon baking soda, or a drop of ammonia, stir well, and check the pH of the water with the pH indicator. If the water is still acidic, repeat the process until pH 7 is reached. Should you accidentally add too much baking soda or ammonia, either start over again or add a drop or two of vinegar, stir, and recheck the pH.
  3. Put one of the following labels on each cup or jar:
    • water philodendron
    • acid philodendron
    • water begonia (or coleus)
    • acid begonia (or coleus)
  4. Pour about a cup of distilled water into the water-philodendron and water-begonia cups.
  5. Pour about a cup of the vinegar/water mixture into the acid-philodendron and acid-begonia cups.
  6. Put one philodendron cutting into each philodendron labeled cup, covering the stem and part of the leaf with the liquid.
  7. Put one begonia cutting into each begonia-labeled cup, covering the stem and part of the leaf with the liquid.
  8. Set the cups where they are not likely to be spilled and where they will receive some daylight.
  9. About every 2 days, check to be sure that the plant cuttings are still in the water or vinegar/water. You may need to add more liquid if the cups become dry.
  10. After 1 week, compare the new root growth of each plant in distilled water with the new root growth of its corresponding plant in acid water. Record the results.
  11. After 2 weeks, again observe the plant cuttings for new root growth, and record the results.

Questions and Answers

Which plant cuttings had the fastest root growth, those in distilled water or those in acid water?

The plants grown in distilled water should grow faster than plants grown in acid water. Acid water, like acid rain, can directly damage plants and slow or stop new growth.


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