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Acid and Bases - Alien I
Task with Student Directions
Contributed by: The RAND Institute (RAND)

Acids and Bases Alien - Form D

Task: In this activity you will be working by yourself. You can write your answers directly on these pages. If you have a question, please raise your hand and we will come to help you.

Please take the materials out of the bag in front of you. Put the materials on your placemat. Raise your hand if you are missing any of these materials:


  • 1 bag pH indicator paper strips
  • 1 pH Color Chart
  • 8 plastic measuring cups
  • 1 dropper bottle Solution X
  • 1 dropper bottle Alien Blood
  • 1 dropper bottle Medicine A
  • 1 dropper bottle Medicine B
  • 1 dropper bottle Medicine C

All solutions are acids, bases, or neutral. You can use pH paper and a pH Color Chart to test whether a solution is an acid, a base, or neutral.


To practice using the pH paper:

  • Squeeze 6 drops of Solution X into one of the measuring cups. Gently swirl the cup.
  • Take one strip of pH paper out of the bag, and dip it into Solution X.
  • Remove the strip from the cup and quickly observe the color of the pH paper. Be sure to look at the color right away, because it will change quickly. The first color shows the correct pH.

1a. What is the color of the pH paper right after you dipped it into solution X? _____________

1b. What number on the pH color chart goes with this color? _____________

1c. Look at the chart below. Is solution X an acid, a base, or neutral? _____________


You are an expert in blood chemistry. The blood of an alien creature is brought to your laboratory for analysis. The alien has a sever headache and a high temperature. The doctors say the alien has a sickness called acidosis-basicosis. This condition is caused by the blood being either too acidic (low pH) or too basic (high pH).

The normal pH for alien blood is 7.0. The alien will die if its blood stays away from 7.0 for more than a few hours.

To find out what is wrong with the alien, test the pH of its blood to see if it is too acidic or too basic.

  • Squeeze 6 drops of the alien's blood into a new measuring cup.
  • Test the pH of the alien's blood using a new strip of pH paper and the color chart.

2a. What was the color of the pH paper right after you took it out of the alien's blood? __________

2b. What number on the pH color chart goes with this color? ___________

2c. The alien is suffering from acidosis/basicosis because its blood is (circle the right choice):

  1. Too acidic
  2. Too basic
  3. Too neutral


The alien's spaceship has a first aid kit with three medicines. One or more of these medicines can cure acidosis/basicosis when it is added to the alien's blood.

Your job is to figure out which medicine ( A, B, or C) will save the alien's life by bringing the pH of its blood back to normal.

You should use the materials in front of you to conduct whatever experiments you think are needed to find out which medicine is best. Remember, always swirl a solution before you test it, and always use a new piece of pH paper for each test.

3a. Record the results of your experiment in the table below as you work.

3b. Write down and number the steps you followed as you conducted your experiment. Be specific, so another student in your class could conduct the experiment exactly as you did. For example, if you mixed solutions together, tell how much of each solution you used.


Use the results of your experiment to answer the following questions:

4a. Which is the best medicine (A, B, or C) for the alien? ______________

4b. Why is this medicine better than the other medicines? (You may use a table, graph, or picture to help you explain your answer).

4c. How can a basic solution be turned into a neutral solution?

4d. How can an acidic solution be turned into a neutral solution?


The people of Spring City were concerned because the fish in their pond were dying. They hired an environmental scientist who measured the pond's pH and found that it was too acidic. Pond fish need neutral water to survive. The people followed the specialist's advice and added Pro-Base, (a strong base) to the pond. After two days, the fish stopped dying. The people kept adding Pro-Base to the water and after three more days, the fish started dying again. In fact, the more Pro-Base they added, the more fish died.

5a. Why did Pro-Base work at first, but not continue to work?

5b. What should the people in Spring City do now to save the fish in their pond? (Circle the best choice)

  1. Add no more chemicals
  2. Add an acidic substance
  3. Add a neutral substance
  4. Add more Pro-Base

5c. Why did you choose this answer?


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