1. Acids, Bases and Buffers

2. Acids Polar substances will dissolve in water
Some compounds tend to fall apart into their separate ions when dissolved in water.
Substances that release H+ (hydrogen ions) when they are placed in water are known as acids.

3. Acids Tend to have a sour taste Citrus fruits Can corrode metals
Can damage tissues in living things
Have a pH lower than 7
React with bases to form salt and water
(neutralization)

4. Are also polar substances
Bases
Are also polar substances
When dissolved in water, substances that release OH- (hydroxide ions) are known as bases.

5. Bases Tend to have a bitter taste Do not corrode metals
Makes them great drain cleaners
Damage tissues in living things
Have a pH higher than 7
React with acids to form salt and water
(neutralization)

6. pH Scale
The pH scale is used to measure the relative strength of acids and bases.
A neutral pH = 7.
pH < 7 = acids
pH > 7 = bases

7. pH Scale
The strength of acids and bases is based on the negative log of their hydrogen ion concentration
For example, if the concentration of H+ in a solution is .001 (1 x 10-3) the pH of the solution is 3
This is because the negative log of 10-3 = 3.
Therefore, an acid that has a pH of 2 is ten times stronger than an acid with a pH of 3.

8. pH Problem
How many times stronger is a solution with a pH of 9 compared to a pH of 2?
The difference in pH = 7
Each pH equals a strength difference of 10X
107 = 10,000,000 X stronger

9. Buffers
Buffers are weak acids or weak bases that can release H+ or combine with H+ to either lower or raise the pH of a solution.
These are very important in maintaining the proper pH of living tissues.
Even a slight change in pH can be fatal to living things.