1. Acids, Bases, and the pH scale

2. Acids
An acid is a compound that releases a proton (a hydrogen ion (H+)) when it dissolves in water.
Because of this, most acids are known as “proton donors”.
If very many protons (hydrogen ions) are “donated” the effect can be very profound, such as burning your skin or dissolving metal.  One acid is hydrochloric acid.  Since nearly all of it is dissociated in water, it is called a strong acid.  Acids that do not dissociate completely are called weak acids.

3. Hydrochloric Acid Burn

4. Bases Bases are compounds that remove H+ ions from a solution.
The most common bases produce -OH or hydroxide ions.
A typical strong base is sodium hydroxide, the principal component of lye.  Sodium hydroxide dissociates to form a sodium ion and a hydroxide ion. A strong base can give your skin a much worse burn than an acid.

5. Sodium Hydroxide (Lye)

6. When a base and an acid are mixed, the hydroxide ion from the base combines with the hydrogen ion from the acid to form water.   This process is called a acid- base reaction.

7. pH Scale
The pH scale measures how acidic or basic a substance is. It ranges from 0-14.
A pH of 7=
A pH less than 7=
A pH greater than 7=
pH of 1 means lots of _______ ions and VERY ACIDIC
pH of 14 means lots of _____________ (or low H+) and VERY BASIC

8. pH Scale

9. pH Scale The scale is logarithmic.
For example, a pH of 4 is TEN times more acidic than a pH of 5 and ONE HUNDRED times more acidic than a pH of 6.  
How much more acidic is a pH of 1 than a pH of 4?
How much more basic is a pH of 10 than a pH of 9?

10. Buffers What is a buffer?
a mixture of molecules that release or bind H+ in order to maintain a relatively stable pH.
Buffers are extremely important to living organisms because most processes in our bodies proceed normally only when the pH remains within a fairly narrow range.
Example: buffers act to maintain blood pH between and 7.45 even though acids and bases are continually being added to and removed from the blood as it travels through the body.

11. What is the effect of adding the buffer?