Acids%20and%20Bases

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Acids and Bases
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What are we going to discuss?

• Tables K and L in the Reference Tables list a few
  of the most common Acids and Bases, but what are
  Acids and Bases.
• Acids and Bases have easy to identify properties.
• In this unit will learn about these properties,
  and the important reactions that occur between
  acids and bases.

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Properties of Acids

• They are electrolytes, that break up into ions in
  water, that conduct electricity in aqueous
  solutions
• Strong acid good conductor
• Weak acid poor conductor
• Sour Taste
• React with most metals to produce H2 (g)
• React with bases to form H2O and salt
• React with indicators to change color
• turn litmus red
• phenolphthalein turns colorless
• pH values are 0.0-6.9
• see Table M for others

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Properties of Bases

• Electrolytes conduct electricity in aqueous
  solutions
• Strong base good conductor
• Bitter Taste
• Feel slippery (like soap)
• React with acids to form H2O and salt
• React with indicators to change color
• litmus turns blue
• phenolphthalein turns pink
• pH values are 7.1-14

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Arrhenius Theory on Acids and Bases

• Arrhenius Acid
• Definition a substance that ionizes in water to
  give hydrogen ions (proton) or a Hydronium ion
  H or H3O
• Ex Hydrochloric acid, HCl (a strong acid).
• HCl (g)? H (aq) Cl- (aq)
• ACIDIC solutions are formed when an acid
  transfers a proton to water.

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Hydronium Ion

• The H interacts strongly with a lone pair of
  electrons on the oxygen of a water molecule. The
  resulting ion, H3O is called the hydronium ion.
• Ex HCl H2O H3O1 Cl-1

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Arrhenius Bases

• Definition a substance that ionizes in water to
  give hydroxide ions OH-
• Example NaOH, NH3
• NaOH (s) ? Na(aq) OH- (aq)
• NH3 H2O ? NH41 OH-

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SALTS

• A salt is an ionic compound that does not produce
  an H ion or OH- ion when dissolved in water.
• Salts are not acids or bases they are neutral
  substances.
• Ex.
• NaCl
• MgCl2

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Naming Acids
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Binary acids two elements - H
hydrogen _____ ide
becomes hydro_____ic acid

• Hydro_____ic acid
• Hydrochloric acid
• Hydrofluoric acid
• Hydrosulfuric acid
• Hydrobromic acid

• Hydrogen _____ ide
• Hydrogen chloride
• Hydrogen fluoride
• Hydrogen sulfide
• Hydrogen bromide

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Ternary acids3 elements H and a
polyatomic ion
Hydrogen _____ate becomes
_________ic acid

• Hydrogen _____ate
• Hydrogen sulfate
• Hydrogen chlorate
• Hydrogen nitrate
• Hydrogen phosphate

• _________ic acid
• Sulfuric acid
• chloric acid
• nitric acid
• Phosphoric acid

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Hydrogen ________ite?_________ ous acid
Hydrogen _____ite becomes
_______ous acid

• _______ous acid
• Nitrous acid
• Sulfurous acid
• Chlorous acid

• Hydrogen _____ite
• Hydrogen nitrite
• Hydrogen sulfite
• Hydrogen chlorite

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Table K and Table L

• These two tables list the most common acids and
  bases.
• The top 4 acids on table K are all strong acids
  while the last 2 are weak acids.
• The top 3 bases on table L are strong bases while
  that last 1 is a weak base.

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Strengths of Acids

• Strong acids ionize completely which means if
  100 molecules dissolve in water all 100 will
  break up into ions
• Examples
• HCl ? H Cl-
• H2SO4 ? 2H SO4-2

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Strengths of Acids

• Weak acids ionize slightly or only a small
  percentage will break up into ions
• Example acetic acid (vinegar)
• CH3COOH ? CH3COO- H
• note if an organic compound ends in COOH its
  a weak acid!!!

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Strengths of Bases

• Strong bases ionize completely
• Example
• NaOH ? Na OH-

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Strengths of Bases

• Weak base ionizes slightly
• Example ammonia
• NH3 H2O ? NH4 OH-

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Acid and Base Reactions

• You will need to be familiar with 2 reactions
  that involve acids and bases.
• The first reaction only involves an acid with a
  metal.
• The second reaction deals with reacting an acid
  with a base to produce a salt and water or
  neutralization.

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Neutralization Reaction

• In a neutralization reaction an Acid will react
  with a base to produce salt and water.
• Three ways we can express neutralization
  reactions
• Word equation
• Formula equation
• Net ionic equation
• A net ionic equation has only the ions that have
  taken part in the reaction. In the reaction the
  ions that do not change are omitted, these ions
  are called spectator ions. See example

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Neutralization
acid base water a salt
Hydrochloric Acid Sodium Hydroxide yields Water
Sodium Chloride
HCl NaOH
HOH NaCl
H(aq) Cl-(aq) Na(aq) OH-(aq)
H2O Na(aq) Cl-(aq)
H(aq) OH-(aq)
H2O
This is the net ionic equation for all
neutralization reactions this equation shows how
the ions are neutralized.
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Try This One
Sulfuric acid sodium hydroxide yields water
sodium sulfate

• H2SO4 2NaOH

2H2O Na2SO4
2H2O 2Na SO4-2
2H SO4-2 2Na 2OH-
H OH-
H2O
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Concentration of H in Acids

• A. 1.0 M HCl (monoprotic acid)
• HCl ? H Cl-
• Produces 1 H so the concentration of H is 1.0 M
• H 1.0 M

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Concentration of H in Acids

• B. 1.0 M H2SO4 (diprotic acid)
• H2SO4 ? 2H SO4-2
• Produces 2 H so the concentration of H is 2(1.0
  M)
• H 2.0 M

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Concentration of OH- in Bases

• A. 1.0 M KOH
• KOH ? K OH-
• Produces 1 OH- so the concentration of OH- is 1.0
  M.
• OH- 1.0 M

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Concentration of OH- in Bases

• B. 1.0 M NaOH
• NaOH ? Na OH-
• Produces 1 OH- so the concentration of OH- is 1.0
  M.
• OH- 1.0 M

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Concentration of OH- in Bases

• C. 1.0 M Ca(OH)2
• Ca(OH)2 ? Ca2 2OH-
• Produces 2 OH- so the concentration of OH- is
  2(1.0 M).
• OH- 2.0 M

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Concentration of OH- in Bases

• D. 1.0 M Mg(OH)2
• Mg(OH)2 ? Mg2 2OH-
• Produces 2 OH- so the concentration of OH- is
  2(1.0 M).
• OH- 2.0 M

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Titration

• An Acid-Base titration is a lab technique used
  find the concentration of an acid or a base by
  neutralizing it.
• During a titration you add volumes of a base to
  an acid until it is neutralized.
• Using the Acid-Base titration formula listed on
  Table T you can solve for your unknown
  concentration.

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Acid- Base Titrations

• MaVa MbVb (Table T)
• Ma molarity of H
• Va volume of acid
• Mb molarity of OH-
• Vb volume of base

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Titration-Setup
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Titrations (Neutralization) Problems

• Ex. What volume of 0.50M HCl is required to
  neutralize 100mL of 2.0M NaOH?
• MaVa MbVb
• Ma .5M
• Va ??
• Mb 2.0M
• Vb 100mL
• Plug in and solve
• 0.5(x) 2.0(100)
• X 400mL HCl
• Try the rest on your own!!!

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pH Scale

• A scale, called the pH scale, has been developed
  to express H as a number from 0 to 14.
• A pH of 0 is strongly acidic
• A pH of 7 is neutral
• A pH of 14 is strongly basic

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pH Scale
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Acid Base Indicators

• An indicator is something that changes its color
  when it gains or loses a proton or an H ion.
• There are several different indicators and they
  change differently when exposed to different pH
  values.
• On your reference tables there is a list of
  common indicators that show the color changes at
  varying pH values.
• See Table M
• You can use multiple indicators to find the
  approximate pH of a substance