2-2 Acids, Bases and pHI. Acids

A. Latin acere = sourB. Properties:

1. Taste sour2. Reacts with some metals to release hydrogen

gas3. Become less acidic when mixed with bases4. Between 0 and 7 on the pH scale(Stronger acids = lower numbers)5. Conduct electricity

C. All acids contain Hydrogen, and when they are dissolved in H2O will release H+ ions in solution.

Example:

HCl + H2O H+ (aq) + Cl-

(aq)

(aq) = aqueous or “in water”

II. Bases

A. Used to be called Alkalies

B. Properties:1. Taste bitter (think aspirin)

2. Feel slimy or slippery

3. Between 7 and 14 on the pH scale

(strong bases = high numbers)

4. Can be very dangerous because they are extremely reactive

5. Conduct electricity

C. All bases contain OH (hydroxide) and will release OH- ions when dissolved in water

Example:

NaOH + H2O Na+ (aq) + OH-

(aq)

(aq) = aqueous or “in water”

III. pH

A. Measures the number of H+ ions in a solution. (pH Stands for potential of hydrogen)

B. Many H+ ions = pH is very low/acidic (ex: stomach acid, vinegar)

C. Few H+ ions = pH is very high/basic (ex: bleach, soap)

D. Same # of each H+ and OH- = neutral 7

(ex: water, blood)

pH Scale

That’s basically it….(get it?)

E. Acids + bases will neutralize each other

H+ (aq) + OH- (aq) H20

F. An acid + a base will always produce water and a salt

Example:

Acid Base Water Salt

HCl +  NaOH H2O + NaCl

(hydrochloric acid + sodium hydroxide = water and salt)

G. Buffers – keep pH from sharply increasing or decreasing = homeostasis

How does pH affect our cells/body?

• Cells must constantly maintain their pH in order to function properly.

• In animals, for example, the maintenance of blood pH is crucial for life. – A slightly acidic pH (6.95) = coma and death.

– A slightly more basic pH (7.7) = convulsions and muscle spasms.

– Carbonic-Acid-Bicarbonate Buffer keeps blood pH close to 7.35 (Kidneys help with this)

Importance of pH in our cells

• The pH of cellular organelles such as lysosomes (pH = 5) is lower than the pH of the cytoplasm (pH ~7.2). • Lysosomes contain enzymes

that function optimally in an acidic

environment.

• This acidic environment would

be detrimental to biological

processes in the cytoplasm.