Acids/Bases/Salts

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Acids/Bases/Salts

• Properties

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Properties
BASES
ACIDS

• electrolytes

• electrolytes

• bitter taste

• sour taste

• turn litmus red

• turn litmus blue

• react with metals to form H2 gas

• slippery feel

• ammonia, lye, antacid, baking soda

• vinegar, soda, apples, citrus fruits

• pH more than 7

• pH less than 7

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Naming

• Acids are composed of hydrogen (H) followed by
  an anion (negative ion).
• If the acid formula contains oxygen in the anion,
  such as in H2SO4, it is known as an oxyacid.

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3 Rules To Naming Acids

• If H anion ending in ide Acid name is
  hydro_____ic acid
• Take the root from the anion name and fill in the
  blank.

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Acid Naming Example

• Example HCl
• Cl is the anion, its name is chloride
• Name of acid is hydrochloric acid
• Example HF
• F is the anion, its name is fluoride
• Name of acid is hydrofluoric acid

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3 Rules To Naming Acids

• H anion ending in ate Acid name is _____ic
  acid
• Take the root from the anion name and fill in the
  blank.
• What I ATE was ICky

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Acid Naming Example

• Example HNO3
• NO3 1- is the anion, its name is nitrate
• Name of acid is nitric acid
• Example H2CO3
• CO3 2- is the anion, its name is carbonate
• Name of acid is carbonic acid

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Exceptions

• Sulfate (SO4 2-)
• Root is not sulf, but sulfur
• Sulfuric acid
• Phosphate (PO4 3-)
• Root is not phosph, but phosphor
• Phosphoric acid

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3 Rules To Naming Acids

• H anion ending in ite Acid name is _____ous
  acid
• Take the root from the anion name and fill in the
  blank.
• Dont bITE its infectiOUS

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Acid Naming Example

• Example HNO2
• NO2 1- is the anion, its name is nitrite
• Name of acid is nitrous acid
• Example HClO2
• ClO2 1- is the anion, its name is chlorite
• Name of acid is chlorous acid

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Writing Formulas

• Just work backwards, using the three rules.
• You must criss-cross charges, just like with
  ionic compounds
• H anion-

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Acid Writing Example

• Hydrobromic acid
• anion is bromide (Br -)
• formula is HBr
• Acetic acid
• anion is acetate (C2H3O2 -)
• formula is HC2H3O2
• Phosphorous acid
• anion is phosphite (PO33-)
• formula is H3PO3

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Naming

• Hydroxide bases are composed of a cation
  (positive ion) followed by hydroxide (OH-).
• Naming bases is much simpler than naming acids.
  Name the cation and then add hydroxide.

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Exception!!!!

• Memorize NH3 ammonia

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Base Naming Example

• NaOH
• name of base sodium hydroxide
• Mg(OH)2
• name of base magnesium hydroxide
• Fe(OH)2
• name of base iron (II) hydroxide

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Writing Formulas

• Writing base formulas is straightforward.
• Find the formula for the cation and then add OH
  -.
• Remember to criss-cross the formula so that the
  charges equal out to zero.

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Base Writing Example

• potassium hydroxide
• cation is potassium (K)
• formula is KOH
• calcium hydroxide
• cation is calcium (Ca 2)
• formula is Ca(OH)2
• aluminum hydroxide
• cation is aluminum (Al 3)
• formula is Al(OH)3

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Electrolytes

• Solutions that have free ions in solution.
• Those free ions conduct electricity.
• Found in sports drinks because body cells need
  ions to do work
• Ex Sodium/Potassium Pump

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Strong Acids

• Strong because there is a strong attraction
  between the acid and the water molecule.
• Every acid molecule ionizes (dissolves)

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Strong Acids

• Perchloric Acid HClO4
• Sulfuric Acid H2SO4
• Nitric Acid HNO3
• Hydriodic Acid HI
• Hydrobromic Acid HBr
• Hydrochloric Acid HCl

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Strong Acids

• If it is not listed. it is considered a weak
  acid.
• Weak- they remain as molecules, they dont ionize
  in water.

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Strong Bases

• Strong because there is a strong attraction
  between the base and the water molecule.
• Every base molecule ionizes (dissolves)

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Strong Bases

• Lithium hydroxide, LiOH
• Calcium hydroxide,
• Ca(OH)2
• Sodium hydroxide, NaOH
• Strontium hydroxide,
• Sr(OH)2
• Potassium hydroxide,
• KOH

• Barium hydroxide,
• Ba(OH)2
• Magnesium hydroxide,
• Mg(OH)2

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Strong Bases

• If it is not listed. it is considered a weak
  base.
• Weak- they remain as molecules, they dont ionize
  in water.

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Indicators

• Chemical dyes that change color as pH changes.
• Different indicators change colors at different
  pH levels
• choose an indicator that will show a color change
  at the pH that you are interested in.
• Indicators can be on a strip of paper
• called pH or litmus paper
• Other indicators can be added to the solution
  directly.
• Some indicators change color more than once and
  can be added to solutions so that we can see what
  is happening over time.

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pH scale

0
14
7
INCREASING ACIDITY
INCREASING BASICITY
NEUTRAL
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pH

• Whether or not a solution is acidic, basic, or
  neutral depends on the balance of H and OH-
  ions
• Neutral H OH-
• Acid H gt OH-
• Base H lt OH-

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pH

• pH is the negative base 10 logarithm of the
  hydrogen ion concentration
• pH - log10 H

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pH calculations (1)

• The sum of the pH and the pOH always equals 14.
• pH pOH 14

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Example

• Find the pH, the pOH 5.3
• pH pOH 14
• pH 14 - 5.3
• pH 8.7

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pH calculations (2)

• pH is the expression of the acidity or alkalinity
  of a solution in terms of its hydronium ion
  concentration.
• pH - log H3O

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Example

• Calculate the pH, if the
• H3O 2.4 X 10-6 M
• pH - log H3O
• - log(2.4 X 10-6)
• -(-5.6)
• 5.6

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pH calculations (3)

• Use an identical equation to calculate pOH.
• pOH - log OH-

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pH calculations (4)

• Use the reverse of the equation to calculate the
  H3O when pH is known.
• H3O 10(-pH)
• 2nd log on the calulator!

10-pH
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Example

• Calculate the H3O, if the pH is 4.71.
• H3O 10(-pH)
• 10 (- 4.71)
• 1.95 X 10-5 M

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pH calculations (5)

• Use identical process for OH- when pOH is
  known.
• OH- 10(-pOH)

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Acid/Bases/SaltsNeutralization/Titrations
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A. Neutralization

• Chemical reaction between an acid and a base.
• Products are a salt (ionic compound) and water.

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A. Neutralization

• ACID BASE ? SALT WATER

HCl NaOH ? NaCl H2O
strong
strong
neutral
HC2H3O2 NaOH ? NaC2H3O2 H2O
weak
strong
basic

• Salts can be neutral, acidic, or basic.

• Neutralization does not mean pH 7.

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Neutralization

• HCl NaOH ?
• HNO3 Ca(OH)2 ?

NaCl H2O
Hydrocholoric acid
Sodium hydroxide
Sodium chloride
Water
Ca(NO3)2 H2O
Calcium nitrate
water
Nitric acid
Calcium hydroxide
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B. Titration

• Titration
• Analytical method in which a standard solution is
  used to determine the concentration of an unknown
  solution.

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B. Titration

• End Point
• point at which an indicator changes color during
  a titration
• Equivalence point
• Point at which equal amounts of H3O and OH- have
  been added.
• when mole ratio exactly equals mole ratio
  required by reaction
• Determined by
• indicator color change

• dramatic change in pH

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B. Titration
moles H3O moles OH- M?V? n M?V? n
M Molarity V volume n of H ions in the
acid or OH- ions in the base
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B. Titration

• 42.5 mL of 1.3M KOH are required to neutralize
  50.0 mL of H2SO4. Find the molarity of H2SO4.

H3O M ? V 50.0 mL n 2
OH- M 1.3M V 42.5 mL n 1
MV MV M(50.0mL)(2) (1.3M)(42.5mL)(1) M
0.55M H2SO4