Acids%20

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Acids Bases
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Properties of Acids Bases

• Acids
• Aqueous solutions of acids have a sour taste
• Turn blue litmus paper to red
• React with metals to produce hydrogen gas (single
  replacement by more active metals)
• React with bases to produce salt and water
• Many acids are electrolytes

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• A binary acid is an acid that contains only two
  different elements hydrogen and one of the more
  electronegative elements

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• An oxyacid is an acid that is a compound of
  hydrogen, oxygen, and a third element, usually a
  nonmetal

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• Bases
• Aqueous solutions taste bitter
• Turn red litmus paper blue
• Dilute solutions feel slippery
• Bases react with acids to produce a salt and
  water
• Bases are electrolytes

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• An Arrhenius acid is a chemical compound that
  increases the concentration of hydrogen ions (H)
  in aqueous solution
• An Arrhenius base is a substance that increases
  the concentration of hydroxide ions (OH-) in
  aqueous solution

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• A strong acid is one that ionizes completely in
  aqueous solution
• Increasingly strong with increasing polarity and
  decreasing bond energy

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• Acids that are weak electrolytes are also weak
  acids
• Molecules with multiple hydrogens are not
  necessarily strong acids, their equilibrium may
  not favor the products
• Organic acids contain carboxylic acid functional
  group (-COOH)

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• Organic acids are generally weak acids
• Many common bases contain metal cations and
  hydroxide ions (these are polar)
• When a base completely dissociates in water to
  yield hydroxide ions, the solution is referred to
  as alkaline
• Ammonia is a base because it produces hydroxide
  ions when it reacts with water
• NH3 H2O ---gt NH4 OH-

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• The strength of a base depends on the extent to
  which the base dissociates
• The alkalinity depends on the concentration of
  hydroxide ions in solution

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Acid-Base Theories

• The Arrhenius definition of acids and bases was
  limited (had to be aqueous)
• Bronsted and Lowry independently expanded the
  definition
• They defined acids as proton donors and bases as
  proton acceptors

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• An acid that can donate only one proton per
  molecule is known as a monoprotic acid
• A polyprotic acid is an acid that can donate more
  than one proton per molecule
• Sulfuric acid is know as diprotic
• Phosphoric acid is know as triprotic
• These are not necessarily stronger acids, depends
  on the degree of dissociation

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• A Lewis acid is an atom, ion, or molecule that
  accepts an electron pair to form a covalent bond
  A Lewis base donates an electron pair
• This is the broadest definition

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Acid Base Reactions

• The species that remains after a Bronsted-Lowry
  acid has given up a proton is the conjugate base
  of that acid (The base also produces a conjugate
  acid)
• Typically equilibrium systems with a forward and
  reverse reaction

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• The stronger an acid, the weaker its conjugate
  base the stronger a base, the weaker its
  conjugate acid
• Proton-transfer reactions favor the production of
  the weaker acid and the weaker base

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• Any species that can react as either an acid or a
  base is described as amphoteric

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• -OH groups can be amphoteric or acidic
• The more polar the OH group, the more acidic the
  compound
• The more electronegative atoms of nonmetals form
  acids with hydroxyl (-OH) groups
• Electronegative oxygens will draw the electron
  density away from the hydroxyl group, making it
  more polar

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• In aqueous solutions, neutralization is the
  reaction of hydronium ions and hydroxide ions to
  form water molecules
• A salt is also produced (an ionic compound
  composed of the cation from a base and the anion
  from an acid)

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