science
...st organisms can only live in a range on the pH scale. Some fungi can grow and survive in acidic solutions, yet they can not survive in a basic solution. Solutions can also be what is known as neutral. The pH of a solution that is nuetral is 7. Distilled water is one example of a neutral substance. A substance is neutral because it contains equal amounts of H+ and OH-. Other neutral substances that were tested are buffer and HCl + NaOH. Some other substances which were close to neutral are tap water, egg yolk, and milk. The most acidic substance which was tested had a pH of 0. This substance was HCl. HCl is the chemical formula for hydrochloric acid. The colorless gas is very acidic and should be handled with care. The substance that was most basic was NaOH. This base has a pH of 14. NaOH is the chemical formula for sodium hydroxide. Sodium hydroxide is a caustic soda or lye and is used for the manufacture of paper, textiles, and detergents. (www.dictionary.com) The pH of hydrochloric acid is less than that of distilled water. The pH of HCl is 0 and the pH of distilled water is 7. In procedure three, mixing of a strong acid and a strong base ocurred. The acid that was used was hydrochloric acid which has a pH of 0. The base was sodium hydroxide which has a pH of 14. When these two substances were mixed they had a pH of 7. The mixture has a pH of 7 because neutralization occurred. Neutralization is a chemical reaction in which an acid and a base react. Complete neutralization can take place when a strong acid, such as hydrochloric acid, HCl, is mixed with a strong base, such as sodium hydroxide, NaOH. Strong acids and strong bases completely break up, or disassociate, into their constituent ions when they dissolve in water. In the case of hydrochloric acid, hydrogen ions, H+, and chloride ions, Cl - , are formed. In the case of sodium hydroxide, sodium ions, Na+, and hydroxide ions, OH - , are formed. The hydrogen and hydroxide ions unite to form water. If the number of hydrogen ions in the hydrochloric acid solution is equal to the number of hydroxide ions in the sodium hydroxide solution, complete neutralization occurs when the two solutions are mixed. The resulting solution contains sodium ions and chloride ions that unite when the water evaporates to form sodium chloride, common table salt. (http://mimp.mems.cmu.edu/~ordofmag/neutralization.htm) Breathing through the straw into water had an effect on the pH of the water. Tap water has the pH of 6.4 yet when the breath was added it dropped to a pH of 6. This signifies that something in breath is acidic. When the carbon dioxide and the water mix it creates what is known as carbonic acid. The chemical formula for carbonic acid is H2CO3. “It is the reaction product of water and carbon dioxide and exists in an equilibrium with water and carbon dioxide whenever the latter is dissolved in the former, for instance in soda water or blood.” (www.dictionary.com) Certain acids are used to make milk sour. Some bacteria digest the lactose found in milk and produce lactic acid. Such bacteria are the bacteria of lactic acid. Lactic acid is a carboxylic acid and its chemical formula is C3H6O3 and its structure is reflected in its systematic name, 2-hydroxypropanoic acid. The process by which this acid is formed is called fermentation of lactic acid because the bacteria of lactic acid do not use oxygen to decompose the nutrients. The fermentation results in the production of carbon dioxide gas. The release of this gas creates the holes seen in cheese. Milk becomes sour due to lactic acid. Fresh milk also has bacteria of lactic...