How strong are acid or base solutions, pH scale, application of pH scale

 

How strong are acid or base solutions?

 

Acid-base indicators are used to distinguish between and acid and a base.

A scale for measuring the hydrogen ion concentration in a solution is known as pH scale. pH is a scale which is used to specify the acidity or basicity of an aqueous solution.

pH scale is logarithmic.

The p in pH stands for Potenz in German which means that power.

And it is inversely indicates the concentration of hydrogen ion in the solution.

On the pH scale , pH is generally measure from 0 (very acidic) to 14 (very alkaline).

The higher the hydronium ion concentration , the lower is the pH value.

The solution with the pH value are neutral solution. Example:-- water. The neutral value of the pH value depends on the temperature.

The solution with pH less than 7 are acidic solution. The pH value can be less than 0 for very strong acids.

The solution with pH value greater than the 7 are basic solution. The pH value can be more than the 14 for strong bases.

As the increases the pH value of the solution from 7 to 14, it represents an increase in OH^- ion concentration in the solution. It means,  it increase the strength of the alkali.

The strength of the acids and bases depends upon the number of H⁺ ions and OH^- ions produced.

 

 

Importance of the pH in everyday life

Are plants and animals pH sensitive ?

Our body works within the pH range value of 7.0 to 7.8.

Living organisms survive only in narrow range of pH change.

When the pH value of the rain water is less than 5.6 , it is acidic rain.

When the acid rain flows into the rivers, it is lower the pH of the river water.

And the survival of the aquatic life in such rivers becomes difficult.

 

pH of the soil

plants require a specific pH value range for their healthy growth. To find out the healthy growth of the plant, we need to take the sample of the soil from the different places. And check the pH value of the soil.

 

pH in the digestive system

our stomach generates the hydrochloric acid.

Hydrochloric acid is used to digest the foods without harming the stomach.

During the indigestion, the stomach generates too much acids and this may causes the pain and irritation. So to come out from such pain , we generally use the bases called antacids.

These antacids neutralises the excess amount of acid produced in the stomach.

Magnesium hydroxide is a mild base which is also used for this purpose.

 

pH changes as the cause of the tooth decay

when the pH value becomes lower than 5.5, the tooth decay gets started.

Tooth enamel is made up of the calcium hydroxyapatite. And it is crystalline form of the calcium phosphate. And it is hardest substance in the body. It does not dissolve in the water, but it is corroded when the pH value of the mouth is below 5.5

The bacteria present in the mouth produce acids by degradation of the sugar and food particles remaining in the mouth after eating.

The best way to prevent this is to clean the mouth after eating meals.

The toothpaste which are generally basic and it is used for cleaning the teeth and can neutralize the excess acids and prevent tooth decay.

Self defence by animals and plants through chemical warfare

Bee- sting leaves an acid which causes pain and irritation.

Use of the mild base like baking soda on the stung area gives relief.

Stinging hair of the nettle leaves inject methanoic acid causing burning pain.

Here, nettle is herbaceous plant.

Nettle grows in the wild.

Its leaves have stinging hair. And its causes painful stings when touched accidentally. This is due to the methanoic acid secreted by them.

A traditionally remedy is rubbing the leaf of the dock plant which grows besides the nettle in the  wild.