ACIDS

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ACIDS BASES
Chapter 5.1
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5.1 Learning Outcomes

• Differentiate between acids, bases and salts with
  respect to chemical formula, name, and
  properties.
• Identify acids and bases using indicators (e.g.,
  methyl orange, bromthymol blue, litmus,
  phenolphthalein, indigo carmine).
• Explain the significance of the pH scale, with
  reference to common substances.
•  
• Recognize the names and formulas of common acids
  (ie Hydrochloric acid, suphuric acid, nitric
  acid, acetic acid).

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5.1 Vocabulary

• Methyl orange
• Methyl red
• Neutral
• Neutralization
• pH indicator
• pH scale
• Phenolphthalein
• Salts

1. Acidic
2. Acids
3. Bases
4. Basic
5. Bromothymol blue
6. Concentration
7. Indigo carmine
8. Litmus

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Interesting Facts
The Scorpion is most notable for "The sting in
the tale" the venom is stored in a bulb like sack
almost at the end of the tail and it is
administered to the unlucky victim through a very
sharp needle point sting.  The venom paralyses
its quarry in a second or less, then the Scorpion
squirts acid from its mouth onto it to dissolve
the tissues before sucking up the slushy remains.
Only 20 species of Scorpion can hurt or kill a
human with a sting. The most dealdy of all is
the 'Death Stalker. It is found in the deserts
of Iraq, Iran, and other neighbouring
countries. It takes up to 12 hours to die after
a sting. First you sweat, then you get dizzy and
get severe pain in your joints. Next the fever
starts, and that leads to convulsions, muscle
spasms and finally coma and death.
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Interesting Facts
Bee stings are acidic with a pH of 3.5. Along
with the acid, the venom that is released by a
wasp or hornet also contains a pheromone which
alarms all other wasps in the area and invites
them to join the attack on the victim. It is
meant to be a signal to all wasps to come and
help. OUCH!! Fire Ants are very aggressive
and will attack anything that disturbs their
mound. After firmly grasping the skin with its
jaws, the fire ant arches its back as it inserts
its rear-end stinger into the flesh, injecting
venom from the poison sac. It then pivots at the
head and typically inflicts an average of seven
to eight stings in a circular pattern. Fire ant
venom has a very high concentation of toxins,
which are responsible for the burning pain
characteristic of fire ant stings.
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Interesting Facts
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ACIDS BASES

• Many familiar compounds are acids or bases.
• Lemon juice, soap, oranges, pop
• Acids and bases can be very dangerous.
• Both can be very corrosive.
• NEVER try to identify an acid or base
  by taste or touch!

See pages 220 - 222
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ACIDS BASES

• The strength of acids and bases in measured on
  the pH scale.
• pH below 7 acidic
• pH above 7 basic
• pH 7 neutral
• 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
• Acids Neutral
  Bases

See pages 220 - 222
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ACIDS BASES
H
Acids release __________ into a
solution. Bases release _________ into a
solution.
OH-
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pH SCALE
H

• pH is the concentration of ____ expressed as a
  logarithm. Every change in the pH scale of one
  unit is a change in ______ times the
  concentration of H. Example
• pH 4 is 10X more acidic than pH 5.
• pH 3 is 1000X more acidic than pH 5.

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Litmus paper, pH paper, neutralization
animations
http//www.bgfl.org/bgfl/custom/resources_ftp/clie
nt_ftp/ks3/science/acids/index.htm
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ACIDS
pH of 0 to 6.9 Contribute H ions into a
solution Turn litmus paper RED Conduct
ELECTRICITY Produce H gas (when added to some
metals) Are CORROSIVE
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Make a Battery from a Lemon!
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ACIDS

• Acids often behave like acids only when
  dissolved in water.
• Therefore, acids often are written with symbol
  (aq) aqueous water.
• The chemical formula of an acid usually starts
  with hydrogen (H).
• HCl(aq) hydrochloric acid, HNO3(aq) nitric
  acid
• Acids with a carbon usually have the C written
  first.
• CH3COOH(aq) acetic acid

See pages 225 - 226
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Sulfuric acid is used in batteries.
ACIDS

• Naming acids If you know a compounds
  chemical formula, you
  may be able to identify
  whether it as an acid.
• Hydrogen -ide hydroic acid
• HF(aq) hydrogen fluoride hydrofluoric acid
• Hydrogen -ate ic acid
• H2CO3(aq) hydrogen carbonate carbonic acid
• Hydrogen -ite ous acid
• H2SO3(aq) hydrogen sulphite sulphurous acid

See pages 225 - 226
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BASES
pH of 7.1 to 14 Donate OH- ions into a
solution The hydroxide OH- group is neutralized
by a hydrogen ion and water is formed. Turns
litmus paper BLUE Conduct ELECTRICITY Are
Slippery Are CAUSTIC
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BASES

• Bases often behave like bases only when
  dissolved in water.
• Therefore, bases often are written with symbol
  (aq) aqueous water.
• If you know a compounds chemical formula, you
  may be able to identify it as a base.
• The chemical formula of a base
  usually ends with
  hydroxide (OH).

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BASES

• Bases can be gentle or very
  caustic.
• Examples of common bases
• NaOH(aq)
• Mg(OH)2(aq)
• Ca(OH)2(aq)
• NH4OH(aq)

See page 227
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Why is it Important to Maintain pH?

• The pH of almost all living systems is between pH
  ________. Maintaining the proper pH then is
  vital living systems.
• pH is very important to the environment as well
• acid rain
• agriculture

6 - 8
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Why is it Important to Maintain pH?
Hydrangea in acidic soil
Hydrangea in basic soil
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pH INDICATORS

• The pH of acids and bases cannot be determined by
  sight.
• Instead, pH is measured by other chemicals called
  indicators OR by a pH meter that measures the
  electrical conductivity of the solution.
• pH indicators change colour based on the solution
  they are placed in.
• Litmus paper is the most common indicator.
• There are 2 colours of litmus paper
• Blue basic (pH above 7)
• Red acidic (pH below 7)

Litmus paper
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pH INDICATORS

• A universal indicator contains many indicators
  that turn different colours at different pH
  values
• can be in liquid form, or on paper strips like
  litmus.
• Indicators change colour at different pH values,
  so different indicators are used to identify
  different pH values.
• Bromothymol blue for pH 6 7.6, phenolphthalein
  for pH 8.2 10.
• Many natural sources, such as beets, blueberries,
  cabbage, pansy flower petals... are also
  indicators.

See pages 223 - 224
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pH INDICATORS
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PEER TUTORS Using a Demonstration Show how
indicators can be switched between their colour
forms an indefinite number of times by placing
phenolphthalein indicator into tap water. Then,
while stirring, add some NaOH solution (0.1 M or
greater) until the solution suddenly turns pink.
Ask students what colour the solution has turned
just to show how many different ways there are to
describe the new colour. Then, add hydrochloric
acid of equal concentration to the base NaOH used
just before. Add, and stir until the solution
loses its pink colour. Ask students what colour
the solution is now. Many students will
incorrectly say clear. While the solution is,
in fact, clear, it was also clear (i.e.,
transparent) even when it was pink. The correct
response is colourless. Finally, add base
followed by acid repeatedly to show that the
indicator is never used upit simply changes from
one colour to the other according to the
prevailing conditions.
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pH INDICATORS
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pH INDICATORS
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pH INDICATORS
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pH INDICATORS
Cabbage Juice paper in baking soda (BASE)
Cabbage Juice paper in lemon juice (ACID)
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pH INDICATORS
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pH INDICATORS
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Production of Ions

• Acids and bases can conduct electricity because
  they
• release ions in solution.
• Acids release hydrogen ions, H .
• Bases release hydroxide ions OH.
• The pH of a solution refers to the concentration
  of HYDROGEN ions it has.
• Square brackets are used to signify
  concentration, H, OH
• High H low pH, very acidic
• High OH high pH, very basic

See page 228
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Production of Ions

• A solution cannot have BOTH high H and OH
  they cancel each other out and form water.
• This process is called neutralization.
• H OH ? H2O OR H OH ? HOH

See page 228
NEUTRALIZATION http//www.youtube.com/watch?v_P
5hGzA6Vb0featurerelated
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In water, the concentration of H is equal to the
concentration of OH-. By definition, pure
water is ______________________ A solution is
ACIDIC if the _______________ A solution is
BASIC if the ________________  
H OH- NEUTRAL
H gt OH-
H lt OH-
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Neutralization Reaction
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Litmus paper, pH paper, neutralization
animations
http//www.bgfl.org/bgfl/custom/resources_ftp/clie
nt_ftp/ks3/science/acids/index.htm
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See page 229