Problem: How much liquid is displaced when baking soda is added to a container of vinegar? How much mass is lost when baking soda is added to vinegar?

Background information:

Define and illustrate meniscus.

Define and illustrate displacement.

Define Acid:

Define Base:

Define Conservation of Mass:

Hypothesis:




Materials: Beaker, graduated cylinder, baking soda, vinegar

Procedure:

1. Measure 50 mL of vinegar in a graduated cylinder.
2. Draw the meniscus.
3. Measure the mass of an empty 250 mL beaker. Record.
4. Pour the vinegar into a 250 mL beaker.
5. Repeat steps 1 and 2, then pour the vinegar into the beaker.
6. Record volume and mass.
7. Draw the meniscus.
8. Obtain a teaspoon of baking soda and measure the mass. Record.
9. Gently place the baking soda in the beaker of vinegar.
10. Record the new volume of the contents of the beaker.
11. Determine the displacement of vinegar in the beaker. Record.
12. Measure the mass of the beaker containing the vinegar and baking soda. Record.
13. Measure the mass of an empty 50mL graduated cylinder. Record.
14. Measure 40 mL of vinegar in a graduated cylinder.
15. Draw the meniscus of the graduated cylinder.
16. Measure the mass of one teaspoon of baking soda. Record.
17. Gently place the baking soda in the graduated cylinder of vinegar.
18. Record the new volume.
19. Record the new mass.
20. Repeat steps 14 through 19 with 20 mL of vinegar.
21. Clean table and equipment. Return clean materials to cart.

Data:

Trial Number	1	2	3
Initial Mass of Beaker (g)
Init. Mass of Graduated Cylinder (g)
Volume of Vinegar (mL)
Mass of vinegar and beaker/graduate cylinder (g)
Mass of baking soda (g)
Mass of vinegar, baking soda and beaker/grad. cyl (g)
Volume of vinegar and baking soda (mL)
Displacement (mL)

Illustrations:


Analysis: Please answer these questions.

1. How did the amount of displacement vary with the initial volume of vinegar?

2. How did the mass of the beaker, vinegar, and baking soda vary with each trial?

Conclusion:

1. Was your hypothesis supported? Why or why not?

 

2. Was the mass of the system conserved (the mass of the beaker and vinegar + the mass of the baking soda = the final mass)? Explain.

 

3. What sources of error did you have?

 

4. If the mass was not conserved, what happened to it?

 

Reflection:

Develop a procedure to measure the volume and mass of vinegar and baking soda before and after reacting with each other. How can you be sure to conserve the mass? Show your teacher your proposed procedure before gathering materials.
Hypothesis: Think about this when you develop your hypothesis: Can you conserve the mass of this system? How?
Materials:


Procedure:



Data:

Trial	1	2	3
Mass of container (g)
Mass of container and vinegar (g)
Mass of baking soda (g)
Mass of system after reaction (g)
Difference in mass before and after (g)

Analysis:  Explain in words what your data shows



Conclusion:

1. Was your hypothesis supported? Why or why not?
2. Was the mass of the system conserved? Explain.
3. What sources of error did you have?
4. If the mass was not conserved, what happened to it?

Reflection:

    

Define acid:

Define base:

Define neutral pH:

Compare and contrast strong acids and weak acids:

Compare and contrast strong bases and weak bases:

Materials (suggestions):

Red cabbage juice water

lemon juice

tomato sauce

ammonia

vinegar

baking soda

Milk of Magnesia

Olive Oil

plant fertilizer

dental rinse

grapefruit juice

pine sol

Pepto-Bismol

soda

Vitamin C

diet soda

lye

potato

eggs

milk

small clear plastic cups

Stir sticks

spot plate/well plate

Procedure:

Day 1:

1. Prepare red cabbage juice in advance by placing 3-4 red cabbage leaves in boiling water for 15 minutes, or until the water turns dark purple.

2. Wear Safety glasses. Label each cup with the name of the substance you will add to it.

3. Gather your substances in your cups. You will only need a Tbsp or so of each substance. Be sure to place only one substance in each cup.

4. Using a new cup, collect about 1/2 cup of cabbage juice and bring it back to your station.

5. Gently pour approximately 1 Tbsp of cabbage juice into each substance cup.

6. Use a stir stick to stir each cup of solution. Be sure to wipe off the stir stick between cups.

7. Record your observations in the chart below.

8. Using color as your guide, line up the substance in order of what you think are their pH levels. Write this in the proposed pH scale table below.

9. Safely dispose of each substance down the sink and clean up your area. Wash your hands.

Day 2

10. Collect an eye dropper full of each substance you tested yesterday in your spot plate.

11. Gently touch the bottom portion of a piece of pH paper in each substance.

12. Use the key provided with the pH paper to determine the pH level of each substance based on the color change of the pH paper.

13. Write the pH level in the actual pH level table below.

14. Wash and dry your spot plate. Return all other items to the appropriate area. Wash your hands.

Data:

Substance	Initial Color and consistency	Color after reaction	Other observations

Proposed pH scale

pH
Substance
Color

Actual pH levels

pH
Substance
Color

Analysis:

1. Identify the color indicators for the red cabbage juice. For example, which color indicated base and which indicated acid?
2. Which substances showed the greatest color change when the cabbage juice was added?
3. Describe your results when using the pH paper.

Conclusion:

1. How did your proposed pH scale compare to the actual pH levels determined by using pH paper?
2. Place the substances in the following categories:

Strong Acids	Weak Acids	Neutral	Weak Bases	Strong Bases

3. Read the ingredients of three of the substances you tested. List the substance and the ingredients you think might have an impact on the pH level.



4. Compare and contrast your proposed pH scale with the actual pH levels.


5. What sources of error occurred for you?


6. Was your hypothesis supported? Why or why not?

Reflection:

Remember the condiments in the fridge and their request for your help? We are finally ready to do as they asked. You will create a poster to hang inside your kitchen cabinet. The poster needs to alert the members of your shelves as to their status on the pH scale. Additionally, post warnings on this document to explain the consequences of acids and bases interacting. Use what you have learned in this unit to help you construct your poster. The illustrations may be originals (you draw them), magazine cut outs, or photographs. The explanations of the interactions must be in your own words, no internet copying. The rubric below lets you know how I will grade your final project. Refer to the rubric to determine what is expected on your poster.

Criteria	Exceeds Expectation	Meets Expectation	Emerging
pH scale	pH scale lists levels from near 0 to 14 in the correct order Hydronium ion concentration listed on the scale for each level Identifies weak and strong levels for acids and bases A visual representation of the logarithmic change from level to level is present	pH scale lists levels from near 0 to 14 in the correct order Hydronium ion concentration listed on the scale for each level Identifies weak and strong levels for acids and bases	pH scale lists levels from 0 to 14
Illustrations	2 or more household items illustrated at each pH level Placement of item matches the actual pH level of the item	1 common household item illustrated at each pH level Placement of item matches the actual pH level of the item	Most pH levels contain an illustration pH level of item matches placement on the scale most of the time
Danger Explanation	Explains what acids and bases are in own words Explains results of interactions between acids and bases Provides examples of interaction and the results for specific acids and bases Identifies methods for avoiding interactions and what to do if a reaction takes place	Defines acid and base Explains results of interactions between acids and bases Provides examples of interaction and the results for specific acids and bases	Defines acids and bases Provides examples of interaction and the results for specific acids and bases, though the interaction may not  be realistic
Time on Task	Always on task during work time Asks questions when clarification is needed Final product is neat, clean, clearly represents learning, and is original	On task 80-90% of the time Poster is clear, visually appealing, and demonstrates an appropriate understanding of acids, bases and the pH scale	On task 70% of the time Poster is complete

Name: ______________________________________________________________________________ Score: __________________________