Acids, Bases and Buffers

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

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

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.

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.

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!

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

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

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 http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_bases_1.shtml

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

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.

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.

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

Depicting Buffer Action

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

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

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

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

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