Strength of Acids                                       pH Scale (Power of Hydrogen ion Scale)
    Strong Acids             Weak Acids                     The strength of acid or base depends upon
pH value: 0, 1, 2, 3     pH value: 4, 5, 6                   the hydrogen ion concentration.
Fully Ionized            Partially Ionized                  pH is a scale which quantifies the
When dissolved in        When dissolved in
                                                             concentration of hydrogen ion in a
water, they give         water, they give
large amounts of H+      small amounts of H+                 solution. The range of pH scale is between
ions                     ions                                0 to 14.
HCl (hydrochloric        CH3COOH (acetic                    Substances with a pH value below 7 are
acid),                   acid),                              acidic.
H2SO4 (sulfuric          HF (hydrofluoric                   Substances with pH value above 7 are
acid), etc.              acid), etc.                         basic.
                                                            Substances with a pH value is 7 are
Base                                                         neutral.
    It is bitter in taste and feels soapy on                         Substance                 pH
     touch. e.g baking soda                                                   Acids
                                                          Hydrochloric Acid (HCl)           0
    It turns red litmus paper blue.
                                                          Sulfuric acid or Battery acid     1.0
    Bases are substances made of hydroxide               Lemon Juice                       2.0
     OH- ions and a metal.                                Vinegar                           2.2
    Common base are : Sodium hydroxide                   Apples                            3.0
     (caustic soda), calcium hydroxide, sodium            Wine and Beer                     4.0
     carbonate (washing soda), lime (Calcium              Tomatoes                          4.5
     oxide), potassium hydroxide (caustic                 Milk                              6.6
     potash)                                                                 Neutral
                                                          Pure Water                        7.0
Properties of Base                                                            Bases
                                                          Human Blood                       7.4
1. When used in aqueous state they are good               Baking        Soda      (Sodium   8.3
     conductors of electricity.                           Bicarbonate)
2. Its pH value greater than 7.                           Ammonia                           11.0
3. Strong bases are corrosive
                                                        Acid-Base Indicators
Types of Base
                                                        Acid - Base indicators (also known as pH
Base can be divided in two types Water
                                                        indicators) are substances which change colour
soluble and water insoluble.
                                                        with pH. They are usually weak acids or bases,
Strength of Bases                                       which when dissolved in water dissociate
                                                        slightly and form ions.
      Strong Bases            Weak Bases
   pH value: 11, 12,     pH value: 8, 9, 10             This range is termed the color change interval.
   13, 14                                               It is expressed as a pH range.
   Completely            Partially ionize and
   ionized in water      equilibrium lies
   to produce            mostly towards
   hydroxide ions        reactants side
   e.g. sodium           e.g. ammonia in
   hydroxide             water
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