Lab+3+-+Water

=__Lab 3 - Water__=

__Exercise 1__
1. //What IS pH?// pH is a method used in order to express how much acid is in a solution. It is measured with a scale that is exponential: one unit change means a ten-fold change (in other words, a solution that has a pH of 1 is ten times more acidic than a solution with a pH of 2). The pH scale ranges from 1-14, and amidst these values describes the concentration of acid. In "science terms", the pH is defined as the "negative logarithm of the hydrogen ion (H+) concentration of activity" (Madscientist Software). Thus, on the pH scale, water has a pH of 7, which means the hydrogen ion concentration os 0.0000001 M/L (or 10 to the minus 7).

2. //What makes hydrogen chemically active?// Hydrogen is chemically active based on how strongly the H+ ion is held in the substance. In acids the hydrogen ion exists; strong ones hold their H+ ion weakly, so it the H+ able to detach and act independently on other substances, while weak acids hold their hydrogen more tightly, so hydrogen is not able to be as chemically active or contribute as greatly to free hydrogen ion concentration. Thus, in the case of weak acids, the solution will have a higher (less acidic) pH, while the stronger acids have a lower (more acidic) pH.

3. //What does it mean when something is acid?// To say something is acid means that the hydrogen ion is held weakly and is therefore able to detach and act independently on other substances. In other words, the free hydrogen ion concentration increases with acidic substances (acidic substances have higher concentrations of the hydrogen ion).

4. //What does it mean when something is basic?// To say something is basic means that the hydrogen ion is held strongly and is therefore not as able to act independently on other substances. They are thought to be opposites of acids, because whereas acids increase the concentration of the hydrogen ion, bases decrease this concentration.

5. //How much more acidic is something that is pH3 than pH 4?// Something with a pH3 is ten times more acidic than a pH4.

6. //How does the acidity or alkalinity of food affect human taste buds?// If food is acidic, it tastes sour, whereas foods that are more alkaline-like are bitter. If the base or acid is too strong, they each can burn one's taste buds. Examples of acidic foods include lemon juice, vinegar, etc., while alkaline foods include ones like sea water, milk of magnesia, etc.


 * //Acid-Base Balance in the Body//**


 * //Carbonic Acid-Bicarbonate Buffering//**

PICTURED ABOVE: Tube 1 = CONTROL, Tube 2 = VINEGAR, Tube 3 = BAKING SODA
 * Results of Using Red Cabbage as a Colorimetric Indicato**r
 * **chemical added** || **number of drops** || **color** || **pH using paper** ||
 * **control** || 0 || light blue || 7 ||
 * **vinegar** || 5 || pink || 4 ||
 * **baking soda** || 90 || very light pink || 5 ||

Lastly, I found NaOH in my lab, and decided to test its effects on the solution. After adding 11 drops the solution became quite yellow/green, and upon testing with the paper, it tests as a pH level 13.

PICTURED BELOW: Tube 1 = NaOH

__Exercise 2__
(after vinegar=5) || (after vinegar=6) || (after vinegar=5) || RESULTS: My testing proved a bit ambiguous, given the difference in the number of drops it took to change each solution. This could have been due to the lack of strength of my initial cabbage-solution, and the ambiguousness of the pink-solution after adding acid. The pH tests from the paper, however, show me that the pH levels were relatively the same at the end, regardless of how many drops (and the variances between each trial) it took to change.
 * Effect of a Buffer on pH change in Reaction to Vinegar Addition**
 * solution || number of drops || color || pH using paper ||
 * control || 0 || light blue || 7 ||
 * B1 (first exercise) || 90 || very light pink || (with baking soda=9)
 * B2 || 21 || very light pink || (with baking soda=9)
 * B3 || 41 || very light pink || (with baking soda=9)

PICTURED BELOW: Tube 1 = CONTROL, Tube 2 = B2, Tube 3 = B3 [**B1 came from Exercise 1, and is Tube 3 in that Exercise]