Edusaint

Bases and Properties, pH in Everyday Life

Bases

  • Bases are those chemical substances which have a bitter taste
  • A base is a substance which dissolves in water to produce hydroxide ions (OHions) in solution.

Properties of Bases

  •  Bases have bitter taste
  •  Bases feel soapy to touch
  •  Bases turn red litmus to blue
  •  Bases conduct electricity in solution (They are electrolytes)
  •  Bases react with some metals to form hydrogen gas
reaction of base sodium hydroxide with zinc metal to form sodium zincate (salt) and release of hydrogen gas
reaction of base sodium hydroxide with zinc metal to form sodium zincate (salt) and release of hydrogen gas
  • Bases react with acids to form salt and water
neutralization reaction between base sodium hydroxide and acid sulphuric acid to form salt sodium sulphate and water .
neutralization reaction between base sodium hydroxide and acid sulphuric acid to form salt sodium sulphate and water .
  • Non-metal oxide + Base—- Salt + Water
chemical reaction between calcium hydroxide and carbon dioxide to form calcium carbonate and water
chemical reaction between calcium hydroxide and carbon dioxide to form calcium carbonate and water

Strength of acid and base solutions: pH scale

  • In pure water, the concentrations of hydrogen ions and hydroxide ions are equal.
  • Due to this, pure water is neither acidic nor basic, it is neutral.
  • The universal indicator shows different colours at different concentrations of hydrogen ions in a solution
  • A scale for measuring hydrogen ion concentration in a solution, called pH scale has been developed.
  • The p in pH stands for ‘potenz’ in German, meaning power.
  • On the pH scale we can measure pH generally from 0 (very acidic) to 14 (very alkaline).
  • pH should be thought of simply as a number which indicates the acidic or basic nature of a solution. Higher the hydronium ion concentration, lower is the pH value
Ph scale showing different region of acidic and basic
Ph scale showing different region of acidic and basic

Importance of pH in everyday life
plants and animals pH sensitive

  • Our body works within the pH range of 7.0 to 7.8.
  • Living organisms can survive only in a narrow range of pH change. When pH of rain water is less than 5.6, it is called acid rain.
  • When acid rain flows into the rivers, it lowers the pH of the river water.
  • The survival of aquatic life in such rivers becomes difficult.

pH in our digestive system

  • our stomach produces hydrochloric acid.
  • It helps in the digestion of food without harming the stomach.
  • During indigestion the stomach produces too much acid and this causes pain and irritation.
  • To get rid of this pain, people use bases called antacids
antacids are use to reduce pain
antacids are use to reduce pain
  • These antacids neutralise the excess acid. Magnesium hydroxide (Milk of magnesia), a mild base, is often used for this purpose
  • pH change as the cause of tooth decay
  • Tooth decay starts when the pH of the mouth is lower than 5.5.
  • Tooth enamel, made up of calcium phosphate is the hardest substance in the body.
  • It does not dissolve in water, but is corroded when the pH in the mouth is below 5.5.
  • Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating.
  • The best way to prevent this is to clean the mouth after eating food.
  • Using toothpastes, which are generally basic, for cleaning the teeth can neutralize the excess acid and prevent tooth decay
toothpaste prevent tooth decay
toothpaste prevent tooth decay
  • Self Defense by Animals and Plants Through Chemical Warfare
  • when a honey-bee stings a person, it injects an acidic liquid into the skin which causes immense pain and irritation
  • baking soda solution on the stung area of the skin gives relief
  • When a wasp stings, it injects an alkaline liquid into the skin.
  • So, if a wasp stings a person, then rubbing a mild acid like vinegar on the stung area of the skin gives relief
  • An ant’s sting injects methanoic acid into the skin of a person causing burning pain.
  • Being acidic, an ant’s sting can be neutralized by rubbing a mild base like baking soda on the affected area of the skin.
  • When a person happens to touch the leaves of a nettle plant accidentally, the stinging hair of nettle leaves inject methanoic acid into the skin of the person causing burning pain.
  • The nettle sting, being acidic, can be neutralized by rubbing baking soda on the skin.

Scroll to Top