WIKI                                                                            pH of  WATER

In this lab you will:

YOU MUST EMAIL ME THE LINK TO YOUR WIKI WHEN YOU ARE FINISHED
 
COLORIMETRIC DETECTION OF PH

Various animal (including human) functions are sensitive to changes in pH due to the sensitivity of enzymes which may only function in a very narrow range of pH.  Go here http://www.madsci.com/manu/gas_acbs.htm
As a result all living things have a buffering system within their cells, and in the fluid that moves between the cells bring oxygen and nutrition. 

In your lab wikibook answer these questions:

1. What IS pH?
2. What makes hydrogen chemically active?
3. What does it mean when something is acid?
4. What does it mean when something is basic?
5. How much more acidic is something that is pH 3 than pH 4? 
6. How does the acidity or alkalinity of food affect human taste buds? 

In your wikibook  write a summary of:

a. Acid-Base Balance in the Body
b. Carbonic Acid-Bicarbonate Buffering
PLEASE use your own words

Creating an organic pH indicator
MATERIALS: Red cabbage, 3 glasses  vinegar, baking soda. 
PREPARATION: pH indicator

1. Tear red cabbage leaves into little pieces, a cuisinart or shredder will work too. 

2.  Run the hot water tap until it is hot, but like for washing dishes hot, 50oC.  Fill the glass with water just to cover the cabbage, no higher.  (remember that 37oC is body temp)

3. Soak for 30 minutes stirring occasionally.  Find another glass that fits inside the first and put enough water inside so it weights the cabbage down under the level of the water. 

4. Pour the solution into your second glass using a fork or your finger to hold the cabbage back.  This is your pH indicator used to detect pH changes. 

http://www.seed.slb.com/en/scictr/lab/food_ph/index.htm


This organic pH solution is COLORIMETRIC, that is, as the pH changes the color changes. In this case it changes for both acid and base. 
Testing the organic pH indicator
MATERIALS: 
METHODS: 

1. Pour equal amounts of your pH indicator into 3 glasses. One is your control.

2. Check and record the color of the solutions in the tubes. 

3. In the first glass use a dropper and add vinegar drop wise, mixing gently with each addition  (just tap the end of the tube) until you see a color change.  Record the color change (1st) and the pH using the paper provided. Then add drops with mixing until there is no further color change (2nd), record the pH. 

At this point label paper A. B. C. D etc and place the paper lined up with the tubes so it corresponds to glasses. Take a clear, not fuzzy picture.  Put a piece of white paper behind the tubes so the color is more apparent. 

Make a table (not a spreadsheet) and record
 
chemical added # of drops 1st color # drops last 2nd color
A) control 0   0  
B) vinegar        
C) soap         
D) etc        
The color of the pH bar is NOT necessarily what color you will find. Take a picture of your glasses when done, insert this into your wikibook. Title the table "Results of using Red cabbage as a colorimetric indicator"

The results table in  both your wikibook  and what you submit needs to clearly show:
- what was added and how many drops or pinches of chemical were added in each tube
- the resulting or "endpoint" color seen in each tube

You may want to look for other liquids in your house that can be added to test for pH change.  Record what you test and your results and take a picture and label as above. 

MATERIALS: red cabbage