Acids, Bases and pH scale

ACIDS Compound that releases Hydrogen ions (H+)

Examples of Common Acids Hydrochloric acid – HCl Hydrosulfuric acid – H2SO4 Nitric acid – H2NO3 What do these formulas have in common?

Acetic Acid - Vinegar HC2H3O2

Lactic Acid Found in foods like yogurt and cottage cheese and sourdough bread Causes muscle soreness

Citric Acid Found abundantly in citrus fruits (lemons, oranges, grapefruit) Used to add a sour taste to foods Flavoring in soft drinks

Formic Acid In the venom of ants and bees HCO2H

Amino Acids “Building blocks” of protein molecules

Bases Bases are compounds that release Hydroxide ions (OH -) in water. Also called alkalines.  

Examples of Common Bases Sodium hydroxide – NaOH Calcium hydroxide – CaOH Magnesium hydroxide – Mg(OH)2 Most soaps and detergents are basic

All compounds are either Acids, Bases, or Neither Chemical Formula Acid Base Neither HF H2SO4 CaOH Mg(OH)2 C6H12O6 HCl NaCl Al(OH)2

pH The measurement of the amount of H+ (hydrogen ions) in solution

pH Scale - Range is 0 - 14 0 1 2 3 4 5 6 7__ 8 9 10 11 12 13 14

Determining a compound’s property from its pH value pH Acid Base Neutral Determining a compound’s property from its pH value 1.3 11.47 7.001 0.1 6.999 3.89 13.0 0.0

Most living things must live in an environment of pH 6.5 – 7.5 HOWEVER, there are some exceptions: Acidophiles – bacteria that live in highly acidic environments. They have evolved a variety of specialized mechanisms to maintain their intracellular pH at a constant level (usually 7.2). Example: L. acidophilus breaks down food in the intestine

Specialized cells in stomach lining make HCl “stomach acid” of pH 1 Parietal Cells

Azalea plants thrive in acidic soil of pH 4.5

Soil pH Alkaline soil makes hydrangeas pink

Acidic soil makes hydrangeas blue

Buffers Help prevent any large changes in pH Buffers are molecules that can bind to an H+ ion when the H+ concentration increases - “locks” it up so the solution doesn’t get more acidic Releases an H+ ion when the H+ concentration decreases

Blood pH and Buffers Normal pH of blood between 7.35 - 7.45 Less than 6.8 or greater than 7.8 is deadly Buffers in blood help prevent any large change in blood pH

Lysergic acid diethylamide