Acids,bases and salts

Important points:

1. Litmus and turmeric are natural indicators.
2. Methyl orange and Phenolphthalein are synthetic indicators.
3. Olfactory indicators : substances whose odour changes in acidic or basic media are called olfactory indicators. Eg Vanilla, Clove oil, Onion etc.
4. Metals react with acids to form salt and hydrogen gas.
5. Bases reacts with metals to form hydrogen gas.
6. Acids reacts with metal carbonates and metal hydrogen carbonates to evolve carbon dioxide gas.
7. Neutralisation reaction: The reaction between an acid and base to form salt and water is called neutralization reaction.
8. Metallic oxides are called basic oxides because they react with acids to produce salt and water as in the reaction between acids and bases.
9. Non-metallc oxidesidic in nature.
10. Glucose and alcohol do not form ions when dissolved in water hence they do not conduct electricity.
11. Bases produce OH- ions when dissolved in water.
12. Bases which are soluble in water are called alkalis.
13. Dilution of acid is done by adding acid slowly and with constant stirring to the water. Water should not be added to the acid as reaction is highly exothermic. The heat generated during reaction may splash out the mixture and cause the burns.
14. Universal indicator is a mixture of different indicators. It is used to detect concentration of hydrogen ions in a solution.
15. pH is the hydrogen ion concentration in a solution.
16. pH scale is the scale for measuring hydrogen ion concentration in a solution.
17. pH of  a neutral solution is 7. The solution with pH value less than 7 are basic solutions.
18. Strong acids: the acids that give rise to more H+ ions are strong acids.
19. Weak acids: Acids that produces less of H+ ions are weak acids.
20. Sulphuric acid , hydrochloric acid, nitric acids are strong acids and acetic acids, citric acid, tartaric acid , oxalic acid are weak acids.
21. Pain and irritation caused by by excessive secretion of hydrochloric acid in stomach is called acidity.
22. Acidity can be relieved by consuming bases called antacids. Eg Magnesium hydroxide and sodium bicarbonate.
23. A tooth enamel consist of calcium phosphate which is corroded by increased value of pH in mouth . Use of basic toothpaste neutralizes  the acid and thus protect from tooth decay.