3. Strongness about Acids or Bases

Strongness  about  Acids or Bases 

Strength of acid and base can be determined by universal indicator.

concentrations of H⁺ ions in the solution.

pH scale :-  A scale for measuring hydrogen ion concentration in a solution called PH scale.

pH = 7                      →     Neutral Solution

pH Less than 7       →      Acidic  Solution

pH more than 7     →      Basic solution

pH of some common substances shown on a pH paper.

Importance of  pH in everyday life :-

1 ,  Plants and animals are Ph sensitive.

• Our body works within the pH range of  7- 7.8 .
• When pH of rain water is less than 5.6, it is called acid rain.
• When acid rain flows into the rivers ,it lower the pH of river water and makes the survival  of aquatic life difficult.

2, pH of the soil

• Plants require a specific pH range for their healthy growth.

3,  pH in our digestive system.

• Our stomach produce hydrogenchloric acid which helps in digestion without harming the stomach.
• During indigestion, stomach produces more acid and cause pain and irritation.
• To get rid of pain ,prople use mild bases called antacid to neutralize the excess acid. Magnesium hydroxide ( Milk of magnesia) is an antacid.

  4,  Ph changes as the cause of tooth decay.

• Tooth decay starts when pH of mouth is lower than 5.5
• Tooth enamel is made up of calcium phosphate ( hardest substance in body) .it does not dissolve in water but carodes when pHis low than 5.5
• Using basic toothpaste , tooth decay can be prevented    

5, self defence by animals and plants through chemical warfare.

• Bee sting leaves an acid which cause pain and irritation. Bakig soda (mild base) gives relief by rubbing it on stung area.
• Stinging hair of nettle leaves inject  methanoic  acid causing  buring or pain rubbing this with leaf of dock plant give relief.