Reference no: EM131708092

Exercise 1: Water and its Unique Properties

Data Table 1.Needle Observations.

Vertical Observations	Horizontal Observations
In the vertical position, the needle sinks to the bottom of the beaker, landing in a horizontal position.	In the horizontal position, the needle floats on top of the water, with the water "bending" slightly above the needle.

Data Table 2. Paper Clips Needed to Break Surface Tension.

Prediction	Result
__9___ Paper clips	_77__ Paper clips

Data Table 3. Drops of Water.

Prediction	Result
__17__ Drops of water	_38_ Drops of water

Data Table 4. Part 4 Observations.

Observations

The capillary action of the celery has allowed it to draw up some of the red colored water.  This has resulted in a slight red coloration of the stalk and a fairly significant red coloration of the leaves.

Questions

A. How did the experiment in Part 1 demonstrate surface tension? Use your experiment observations when answering this question.

B. In Part 1, when adding the needle to the water, which approach worked best to balance the needle on the water-the vertical or horizontal placement? Explain your answer.

C. In Part 2, how did your paper clip estimation compare to your paper clip results?

D. In Part 3, how were the properties of adhesion and cohesion demonstrated in the experiment?

E. How did the activity in Part 4 demonstrate capillary action? Explain your answer using your experiment results and observations.

Exercise 2: Testing Common Household Materials for pH Values

Data Table 5. pH Observations.

Well Plate	Item Tested	Commercial pH strip		Homemade pH strip
		Color	pH	Color	pH
1	HCl (hydrochloric acid)	Pink	1	Deep red	2
2	NaOH (sodium hydroxide)	Green	9	Deep blue	12
3	Distilled water	Light blue or light purple (no noticeable change)	7	Yellow (no noticeable change)	7
4	Dish Soap (Palmolive)	Pink	1	Orangish-yellow	6
5	Lemon Juice	Pink	1	Orange	4
6	Creatine Drink	Pale Purple	3	Orangish-yellow	6
7	Soy Sauce	Orangish-brown	12	Orangish-yellow	6
8	Milk	Light blue or light purple (no noticeable change)	7	Greenish-blue	9
9	Pine-Sol	Pink	1	Orangish-yellow	6
10	Leather Cleaner	Blueish-green	9	Green	8
11	Furniture Oil Polish	Pale blue	4	Yellow (no noticeable change)	7
12	Hand Soap	Pale purple	3	Yellow (no noticeable change)	7

Data Table 6. Analysis of Results.

Well Plate	Item Tested	Acid/Base/ Neutral?	Explanation:
1	HCl(hydrochloric acid)	Acid
2	NaOH(sodium hydroxide)	Base
3	Distilled water	Neutral
4	Dish Soap (Palmolive)	Acid
5	Lemon Juice	Acid
6	Creatine Drink	Acid
7	Soy Sauce	Acid?
8	Milk	Base
9	Pine-Sol	Acid
10	Leather Cleaner	Base
11	Furniture Oil Polish	Neutral?
12	Hand Soap	Neutral?

Questions

A. Compare and contrast the results between the commercial and homemade pH test strips. Which test strips were more accurate? Explain your answer.

B. Why is the pH scale important in science? Give several examples of scientific applications.

C. What information about a chemical can be inferred from knowing its pH value?

D. If a chemical has a pH of 3, how could you change its pH value to be more basic?

Exercise 3: Buffers in a Living System

Data Table 7.pH Change of Buffered and Un-buffered Solutions.

	Un-buffered Solution	Buffered Solution
Initial pH	7	8
+ 3 drops HCl	6	8
+ 6 drops HCl	5	8
+ 9 drops HCl	4	8
+ 12 drops HCl	4	7.5
+15 drops HCl	4	7.5
+18 drops HCl	4	7

Data Table 8. Graph of pH Changes.

Graph of pH changes

Questions

A. Analyze the results of your experiment. Did the buffer resist changes in the pH? Explain your answer using your experiment results.

B. Research the bicarbonate buffering system found in the blood stream. Write a paragraph or two discussing this system and how your breathing rate can cause acidosis and alkalosis.