Acids, Bases, and Buffers

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Acids, Bases, and Buffers

• Niki Tillotson
• Ben McCullough
• Shara Wang

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Outline

• Acids
• Overview
• Strong Vs. Weak Acids
• Acidosis
• Bases
• Overview
• Strong Vs. Weak Bases
• Alkalosis
• Buffers
• Overview
• Example of a Buffer

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Acids - Overview

• When dissolved in water
• ...increases amount of hydrogen ions (H)
• ...over what is present in the pure solvent
• ...Hydrogen ion (H) donor

• Binary acids H another element (e.g. HF)
• Oxoacids H O another element (e.g. HClO4)
• Organic acids compounds of carbon (e.g.
  C6H5COOH)
• Examples vinegar cola tomatoes DNA
  RNA

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Strong Vs. Weak Acids

• Weak acids
• Weak electrolyte
• Slightly soluble or insoluble in water
• Can neutralize strong bases
• Ex acetic acid
• CH3COOH

• Strong acids
• Strong electrolytes
• Dissociate essentially completely in water
• Ex nitric acid HNO3

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Acidosis

• Kinds of Acidosis
• Respiratory - excessive CO2
• Diabetic - extra ketone bodies accumulated during
  uncontrolled diabetes
• Hyperchloremic - excessive chloride in blood
• Lactic - accumulation of lactic acid

• A condition of excess acid in the body fluids
• Caused by an accumulation of acid or
  significant loss of bicarbonate
• Sometimes treated with IV administration of
  solutions containing hydrogen carbonate ions

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Bases (Also Called Alkalis)

• Bases counteract or neutralize the properties of
  acids
• An Arrhenius base is a substance that, when
  dissolved in water, dissociates to OH- ions
• It is a hydroxide ion (OH-) donor
• Bases generally feel slippery or soapy and taste
  bitter
• Examples of bases
• Soaps Detergents Cleansers Bleach

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Strong Vs. Weak Bases

• Strong bases
• Strong electrolytes
• Dissociate essentially completely in water
• Ex sodium hydroxide NaOH

• Weak bases
• Weak electrolyte
• Slightly soluble or insoluble in water
• Recognized by their ability to neutralize acids
• Ex ammonia NH3

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Alkalosis

• A condition of excess base in the body fluids
• Decreased carbon dioxide or increased bicarbonate
  levels create an excessive alkaline state
• Sometimes treated with IV administration of
  aqueous ammonium chloride

• Kinds of Alkalosis
• Respiratory - lower CO2 levels
• Metabolic - excess bicarbonate in blood
• Hypochloremic - extreme lack of chloride
• Hypokalemic - kidneys reaction to an extreme
  loss of potassium
• Compensated - body has partially compensated for
  alkalosis even though bicarbonate and CO2 levels
  remain abnormal

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Buffers

• Most living cells need to live in an area with a
  near constant pH.
• Buffers aid in the steadying of pH levels.
• Buffers accept hydrogen ions (H) when they are
  excessive and donate them when their supply has
  been depleted
• The majority of buffers are weak acids or bases
  that combine reversibly with hydrogen ions (H)
• Most buffers are acid-base pairs

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Example of a Buffer

• Carbonic Acid
• To maintain pH of 7.4

H2CO3 ? HCO3- H
HCO3- H ? H2CO3
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Useful Links

• www.science.ubc.ca/chem/tutorials/pH/index.html
• http//bird.miamisci.org/ph/lpexplore1.html