Acids and Bases Alien - Form R

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:

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

Part 1: READING THE pH SCALE

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 will do this in two stages. In Stage I, you will test the pH of each medicine. In Stage II, you will test what happens when you combine the alien's blood with each medicine.

Follow the steps below and record the results of your experiment in Table 1 as you work.

Stage I - Testing the Medicines

1. To test Medicine A:
   
   
   
   
2. Record your results in Table 1, making sure that you describe both the color of the pH paper and its pH number.
   
   
3. Repeat steps 1 and 2 for Medicine B with a new cup and new pH strip.
   
   
4. Repeat steps 1 and 2 for Medicine C with a new cup and new pH strip.

Stage II - Testing Mixtures

5. Fill a new cup up to the 5ml level with alien blood.
   
   
6. Add 3 drops of Medicine A to the cup, gently swirl the cup, dip a new piece of pH paper into the solution, and quickly match the color on the pH paper with the Color Chart.
   
   
7. Record the color of the pH paper and the pH number in Table 1.
   
   
8. Add 3 more drops of Medicine A to the cup, gently swirl the cup, dip a new piece of pH paper into the solution, and quickly match the color on the pH paper with the Color Chart.
   
   
9. Record the color of the pH paper and the pH number in Table 1.
   
   
10. Repeat steps 5-9 using Medicine B.
    
    
11. Repeat steps 5-9 using Medicine C.
    
    

Part 4: DRAWING CONCLUSIONS

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?

Part 5: USING WHAT YOU LEARNED

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?