Recn with oxides
-> All metal oxide and metal hydroxide are basic in nature.
format:- Acid + Metal oxides → Salt + Water
e.g.
-> When hydrochloric acid react with calcium oxide then it produce calcium chloride along with H2O.
format:- Acid + Metal hydroxides → Salt + Water
e.g.
-> When hydrochloric acid react with calcium hydroxide then it produce calcium chloride along with H2O.
-> When sulphuric acid react with zinc oxide then it produce zinc chloride along with H2O.
format:- Base + Non-metal oxides → Salt + Water
e.g.
-> When sodium hydroxide react with carbon dioxide then it produce sodium carbonate along with H2O.
-> When calcium hydroxide react with carbon dioxide then it produce calcium carbonate along with H2O.
e.g. ZnO, Al2O3, etc.
-> When hydrochloric acid react with zinc oxide then it produce zinc chloride along with H2O.
-> When hydrochloric acid react with aluminium oxide then it produce aluminium chloride along with H2O.
-> When aluminium oxide react with sodium hydroxide then sodium aluminate is produced along with water.
* Neutral Oxides- Oxides which are neither acidic nor basic are called neutral oxides.
e.g. Carbon monoxide (CO), Nitrous oxide (N2O); Nitric oxide (NO), etc.
Note:- Both acid and base conduct electricity because of presence of ions in its aqueous solution.
-> The process of dissolving an acid or a base in
water is a highly exothermic one. So, care must be taken, while mixing concentrated acid in water.
The acid must always be added slowly to water with constant stirring.
-> If water is added to a concentrated acid then the generated heat may cause the mixture to splash out and cause burns and the glass container also break due to excessive heat.
-> The strength of acids and bases depend on the number of H+ ions and OH- ions produced respectively in aqueous solution.
* pH- The term pH stands for “Potential of Hydrogen” and the pH scale is used to determine the acidity and basicity of a substance.
For water or neutral solutions:- pH = 7
For acidic solutions:- pH < 7
For basic solution:- pH > 7
Importance of PH in everyday life
(i) pH in our digestive system- Our stomach produce HCl. It helps in digestion of food. During this process, sometimes the stomach produces too much acid and this causes pain and irritation inside stomach.
To get rid of this pain, we use a base called antacid. Antacids like magnesium hydroxide [Mg(OH)2] also known as milk of magnesia and sodium hydrogen carbonate (baking soda) are used to neutralize excess acid.
(ii) Tooth decay caused by acids- The bacteria present in our mouth converts the sugar into acids. When the pH of acid formed in the mouth falls below 5.5,
tooth-decaying starts.
The excess acid has to be removed by cleaning the teeth with a good quality toothpaste because these kinds of toothpaste are alkaline in nature.
(iii) Soil of pH and plant growth- Most of the plants have a healthy growth when the soil has pH range of 6 to 7.5 which is neither alkaline nor highly acidic.
(iv) pH range of Human Body- Our body works within the pH range of 7 to 7.8 (mild basic).
(v) Acid rain- When pH range of rain water is less than 5.6, then that rain water is termed as acid rain. When acid rain flows into the river, it decreases the pH range of the river water and the survival of aquatic life in such rivers become difficult.
(vi) Insect stings- When insect bites then we feel pain and irritation in the body.
Ant sting release Methanoic acid (HCOOH) in our skin and Wasp sting release a
type of alkaline liquid.
| Insect Sting | For Treatment |
|---|---|
| Wasp Sting | Vinegar |
| Ant Sting | Baking Soda |
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