Liquids may be an acid, base, or neutral. The way to tell which one a liquid is, is to use a pH scale. It measures the acidity in a liquid to tell if it is an acid, a base, or if it is neutral. The scale ranges from 0 to 14. Liquids with a pH of 0 to 6 are acidic. Liquids with a pH of 7 are neutral. Liquids with a pH of 8 to 14 are basic. Water is neutral with a pH of 7. However when it mixes with the air, its pH can either be raised or lowered by the suspended materials in the air. This can cause acid rain.
Students will determine the pH of various substances and their effect on organisms in the environment.
The materials used were wide range pH paper and chart, spat plate, forceps, soapy water, lemon juice, ammonia, cola, distilled water, pond water, salt water, baking soda solution, and 8 dropper bottles.
Using a spot plate, place a couple of drops of each solution into the numbered wells being careful not to mix the solutions. Well 1 should hold the soapy water, well 2 the lemon juice, well 3 the ammonia, well 4 the cola, well 5 the distilled water, well 6 the pond water, well 7 the baking soda solution, well 8 the vinegar. Using forceps pick up a piece of pH paper. Touch the pH paper to the liquid in well 1 and remove it. Compare the color of the pH paper to the pH color chart. Record the pH on your data table. Repeat steps 2-5 for each of the other solutions. Be sure to use a new piece of pH paper each time.
The pH of Tested Solutions
1. Which liquid had the lowest pH? Lemon Juice
2. Which of the liquids had the highest ph? Ammonia
3. Which of the liquids was closest to being neutral? Pond water
4. If the pH of a sample 3, how many times more acidic is it than a solution with a pH of 6? 1,000 times more
5. How might someone correct the pH of a lake with a reading of 3? By adding pure water to normal lake water.
6. What would be the pH of human blood? 7, neutral
7. How does non-tearing shampoo work? Non-tearing shampoo is not acidic or basic, but neutral. This way it does not burn your eyes.
8. What would be the likely pH of acid rain? 4
9. What industries in out area pump materials into the atmosphere to create a drastic change in rain water? (Hint: Some days you can smell this industry. The rice mill, and the paper mill.
10. List any substances that had a pH that would cause tadpoles and fish to die.
Lemon juice, cola, and vinegar would.
The pH meter never fully settled on an exact pH number. It also had water left in it from being rinsed out between measuring solutions.
Discussion and Conclusion:
The hypothesis stated that the students were to determine the pH or various substances and their effect on organisms in the environment. The various substances and their pH were soapy water-8.76, lemon juice-2.55, ammonia-11.41, cola-3.35, distilled water-9.21, pond water-8.00, baking soda-8.08, and vinegar-2.68. The effects on organisms in the environment were that lemon juice, cola, and vinegar had a pH that would cause tadpoles and fish to die