Acids, Bases, Salts and pH

							Acids, Bases, Salts and pH


      Joe Walker Middle School
          Physical Science
             Hayhurst/Sour
Acids
Acids are chemicals in which the positive ion
  is a hydrogen atom.
 for example; HCl or H2SO4
 When mixed with water they produce a free
  hydrogen ion that combines with a water
  molecule to produce a hydronium ion (H3O)
   H+1 + H2O  H3O+1
 An acid is a substance that releases
  hydrogen ions when it breaks apart in water.
Physical Properties of Acids
1. Taste sour

2. React with metals to produce hydrogen
  2HCl + 2Na  2NaCl + H2

3. Conduct electricity.
Bases
 Bases are substances in which the negative
  ion is an ion called hydroxide (OH)-1.
 For example; NaOH, or KOH
   – used to make soap, household cleaners,
     fertilizers, and explosives.
Physical Properties of Bases
1. Taste bitter
2. Feel slippery
3. Conduct electricity
4. Sometimes Caustic. That is they eat away
  at certain substances and they are irritating
  or damaging to skin.
Salts
 A salt is a compound formed from the
  positive metal ions of a base and a negative
  nonmetal ion of an acid.
 For example NaCl, K2SO4
 Are the product of a reaction between an
  acid and a base, along with water.
Physical Properties of Salts
 They form crystals when in solid form
 They usually have a higher hardness
  because of their ionic bonding.
 An acid plus a base yields a salt and water.
   HCl + NaOH  NaCl + HOH
   or
   HCl + NaOH  NaCl + H2O
Neutralization
 A reaction between an acid and base.
 The products of a neutralization reaction are
  a salt and water.
The pH Scale
   The pH scale gives a measure of the
    concentration of positive hydrogen ions in a
    solution.
     – a way of describing the acidic or basic
       strength of a solution.
     – the acidity of a solution can be expressed
       by using the pH scale
The pH Scale
 the scale ranges from 0 to 14
 acids range from 0 to 7, with 0 being the
  strongest acid
 bases range from 7 to 14, with 14 being the
  strongest base.
 pure water, which is neither acid nor base,
  has a pH level of 7 or is neutral
Indicators
 Indicators are substances that visibly show a
  change in the nature of a chemical system.
 Universal indicator- an acid/base indicator
  that shows, by color, the pH of a substance.


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ACIDIC                 NEUTRAL            BASIC