EXERCISE 1: 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?
A pH is the measure of the basicity or acidity of a solution dissovable in water.
2. What makes hydrogen chemically active?
Hydrogen is a very unstable element that has only one electron and is very willing to bond with another.
3. What does it mean when something is acid?
An positive ion is a substance that accepts an electron(s) in order to form a covalent bond. An acid produces these bonds with a base.
4. What does it mean when something is basic?
To be a base substance means that an object is a negative ion and gives an electron to an acid to form a covalent bond.
5. How much more acidic is something that is pH 3 than pH 4?
There is not too big of a difference between pH 3 and pH 4. Both of these fall under the category of acid rain. A comparison is a tomato juice (pH 4) vs. orange juice (pH 3).
6. How does the acidity or alkalinity of food affect human taste buds?
An acidic object will give off a sour taste while alkalinity gives off a soapy taste.

In your wikibook write a summary of:
a. Acid-Base Balance in the Body
Our body is very sensitive to the acid-base balance, or pH, so it is tightly regulated. It is a process of homeostasis in which strong mechanisms work to keep it at the right level. There are several buffering agents in the body that work to impede the process of change of pH level.
b. Carbonic Acid-Bicarbonate Buffering
This buffer is the most important within the body for regulating acid-base balance and is in the blood.

Make a table (not a spreadsheet) and record

Photo0039.jpg
First Table: Left (Vinegar), Middle (Baking Soda), Right (Control)



Results of Using Red Cabbage as a Calorimetric Indicator
chemical added
number of drops
color
pH using paper
control
0
faint purple
8
vinegar
15
light pink
3
baking soda
8
faint sky blue
6
Photo0040.jpgThis is the Vinegar Solution Photo0041.jpgThis is the Baking Soda Solution
The color of the pH bar is NOT necessarily what color you will find. external image camera.jpgTake a picture of your tubes 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
- the pH of the endpoint according to the standard pH paper

Now rinse out the 2 tubes that are NOT the control and ....
Look for other liquids in your house (in the lab) that you can add dropwise to test for pH change. Record what you test and your results and take a picture and label as above. Be sure to save the rest of your pH solution for the next exercise.


EXERCISE 2: DETERMINING THE RESISTANCE OF A BUFFER|| METHODS:
1. Add 3 ml of your pH solution to two tubes and label them (C) control and B (for buffer). 2. In B add a pinch of baking soda and record color and pH (paper)
3. Start adding vinegar to each tube drop by drop until you see the pink color of acid. Record the number of drops of vinegar it takes to see pink. You can repeat this experiment a total of 3 times, average the number of drops (each drop is 0.05ml) and see how precise your exercise has been. Use the pH paper to determine the actual pH before and after addition of acid.

Effect of Buffer on pH Change In Reaction of Vinegar Addition

Color
pH
Trial 1
Trial 2
Trial 3
Average
Control
Faint Blue
9
28



Baking Soda


8
6
7
7
Photo0042.jpg