Acids, Bases, Salts

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Acids, Bases, Salts
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Acid Information

• An acid is a compound that produces hydronium
  ions (H3O1 or combined hydrogen) when dissolved
  in water
• Acids taste sour.
• Acids turn indicators red
• Show reactivity when combined with metals

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Hydronium Ions

• The protons released (in the form of hydrogen)
  are not normally found uncombined in solution.
• The H1 combines with water to form H3O1
  (hydronium ion)
• Any solution that contains hydronium ions is
  acidic

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Strong vs Weak Acids

• The more hydronium ions the acid produces in
  solution, the stronger the acid.
• Strong acids ionize completely, forming many
  hydronium ions (the water solution contains only
  ions there are no molecules of the acid left)
• Weak acids do not ionize completely

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Strong Acids

• Strong acids are very corrosive. They react with
  metals and can cause severe burns on the skin.
• Strong acids
• Hydrochloric HCl
• Nitric HNO3
• Sulfuric H2SO4
• Hydrobromic HBr

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Weak Acids

• Weak acids are often organic acids.
• All organic acids contain a COOH group (which
  ionizes and provides the H1 that makes a
  compound an acid.
• Formic acid HCOOH (ants)
• Acetic acid CH3COOH (vinegar)
• Salicylic acid C6H4(OH)COOH (aspirin)
• Citric acid C5H7O5COOH (citrus)

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Bases

• Bases are ionic compounds containing metal ions
  and hydroxide ions.
• Bases taste bitter and feel slippery
• Bases turn indicators blue
• Bases release hydroxide ions in water solutions
  (the more released, the stronger the base)

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Titration

• Titration is a technique for measuring the
  relative strength of a solution.
• Endpoint is the point in a titration where equal
  amounts of reactants are present.
• Buffers are solutions which can receive moderate
  amounts of acid or base with significant changes
  in pH

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Indicators

• Indicators are weak organic acids or bases which
  have the property of changing color in solution
  when the hydrogen ion concentration reaches a
  definite value.

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Common Bases

• Sodium hydroxide NaOH
• Calcium hydroxide Ca(OH)2
• Magnesium hydroxide Mg(OH)2
• Ammonium hydroxide NH4OH

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Bases

• Although many bases contain hydroxide ions, there
  are some that do not. Ammonia, for example,
  produces a hydroxide ion only when it is
  dissolved in water.

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Salts

• In general, salts are ionic compounds composed of
  metallic ions and nonmetallic ions
• Salts dissociate in water. Salt solutions are
  generally electrolytes.
• An electrolyte is a substance that ionizes or
  dissociates into ions when it dissolves in water
  (conducts electricity)

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Salt Water

• The reaction of a salt and water to form an acid
  and base is called hydrolysis. This is the
  reverse of a neutralization reaction in which
  acid and bases react to form a salt and water.

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Proton Donors and Acceptors

• Acids lose or donate protons. When acid and
  base react in water, a proton from the hydronium
  ion combines with the hydroxide from the base to
  form water.
• Bases accept protons.
• Water can act as either acid or base depending on
  compound with which it reacts.

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pH scale

• The pH scale is a measure of the hydronium ion
  concentration.
• A pH of 7 indicates a neutral solution while
  acids are less than 7 and bases greater than 7

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More on pH

• If you add an acid to water, the concentration of
  hydronium ions increases and the concentration of
  hydroxide decreases.
• The lower the pH value, the greater the hydronium
  ion concentration.

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Example

• Supppose you have a HCl solution with
  concentration of hydronium ions of 0.10 M (or
  written another way 1 E -1 M).
• This solution has a pH of 1.

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Still more on pH

• If you add base to water the concentration of
  hydroxide increases and the hydronium ion
  concentration decreases.
• The higher the pH value, the lower the hydronium
  ion concentration.

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Example

• Consider a NaOH solution with a concentration of
  hydroxide is 0.10 M. The concentration of
  hydronium ions is 1.0 E -13 M.
• This concentration corresponds to a pH of 13.

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Dissolving Review

• Dissociation process in which an ionic compound
  separates into ions as it dissolves (ions pulled
  into solution are same ions present in solute)
• Ionization process in which neutral molecules
  can or lose electrons (ions in solution are
  formed by reaction of solute and solvent
  particles)