1. Acids, Bases and Buffers

2. What is the pH scale?
The pH scale measures how acidic or basic a solution is
pH= potential of hydrogen

3. Ways to determine the pH
Litmus Paper: indicates if acidic, basic, or neutral by color.
*pH paper: Gives an approximate pH of solution by color of the paper.
Indicators: a chemical added to the solution which tells pH by color change.
pH Meter: monitors pH using the Labpro and gives a readout of the measured pH

4. Why is pH important in biology?
pH affects solubility of many substances.
pH affects structure and function of most proteins - including enzymes.
Many cells and organisms (esp. plants and aquatic animals) can only survive in a specific pH environment.

5. Identifying Acids and Bases
Acids have a pH from 0-7
Lower pH value indicates a stronger acid.
Bases have a pH from 7-14
Higher pH value indicates a stronger base.

6. Did we Miss something?? What happens when the pH of a substance is 7?
Ans: A pH level of 7 indicates a Neutral Substance i.e: Water!

7. LecturePLUS Timberlake
Acids and Bases
Acids produce H+ in aqueous solutions
water
HCl H+(aq) + Cl- (aq)
Bases produce OH- in aqueous solutions
NaOH Na+(aq) + OH- (aq)
LecturePLUS Timberlake

8. Test Your Knowledge What is the range of an ACID on the pH scale?
Ans: 0-7
What is the range of a BASE and what is another name for a BASE?
Ans: 7-14, Alkaline

9. Properties of an Acid Tastes Sour Conduct Electricity
Corrosive, which means they break down certain substances. Many acids can corrode fabric, skin,and paper
Some acids react strongly with metals
Turns blue litmus paper red
Picture from BBC Revision Bites

10. Uses of Acids Acetic Acid = Vinegar
Citric Acid = lemons, limes, & oranges. It is in many sour candies such as lemonhead & sour patch.
Ascorbic acid = Vitamin C which your body needs to function.
Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics.
Car batteries

11. Properties of a Base Feel Slippery/soapy Taste Bitter Corrosive
Can conduct electricity. (Think alkaline batteries.)
Do not react with metals.
Turns red litmus paper blue.

12. Uses of Bases
Bases give soaps, ammonia, and many other cleaning products some of their useful properties.
The OH- ions interact strongly with certain substances, such as dirt and grease.
Chalk and oven cleaner are examples of familiar products that contain bases.
Your blood is a basic solution.

13. Buffers A solution that resists change in pH
Maintains pH with small additions of acid or base
Maintains homeostasis

14. Depicting Buffer Action

15. Buffer Importance for proteins
Enzymes (protein) require an optimal pH to function properly
denaturing can occur, they are no longer active
This can happen in too high or too low pHs for that specific enzyme

16. Homeostasis
Process of a system that regulates its internal environment
tends to maintain a stable, relatively constant condition
Ex: body temperature ,blood pH, water, glucose levels, skin pH
pH needs to be regulated to maintain homeostasis and normal function

17. Buffers in blood
Human blood plasma needs to have a pH between 7.35 and 7.45
Any lower causes a condition called acidosis
Any higher causes a condition called alkalosis
The pH of blood is controlled by a mixture of buffers

18. Think-Pair-Share Why are buffers important to our body?
Explain to the person next to you

19. Left-side Activity