Acid And Base
- 1. ACID AND BASE Meaning: An acid is a chemical substance which ionises in water to produce hydrogen ions, H + or hydroxonium ion, H 3 O + . A base is a chemical substance which reacts with acid to produce salt and water A alkali is a chemical substance which ionizes in water to produce hydroxide ions, OH - Faridah Hamat SASER 2008
- 2. Strong Acid, Weak Acid Strong acid: Acid which ionizes completely when dissolve in water to produce high concentration of hydrogen ion, H + Example: HCl, HNO 3 , H 2 SO 4 HCl H + + Cl - H + + H 2 O H 3 O + (Hydroxonium ion) Faridah Hamat SASER 2008
- 3. Cont…. Weak acid: Acid which ionises partially when dissolve in water to produce low concentration of hydrogen ion, H + Example: Ethanoic acid CH 3 COOH CH 3 COO - + H + Faridah Hamat SASER 2008
- 4. Strong Alkali, Weak Alkali Strong alkali: Alkali which ionizes completely when dissolve in water to produce high concentration of hydroxide ion, OH - Example: NaOH, KOH Weak alkali: Alkali which ionises partially when dissolve in water to produce low concentration of hydroxide ion, OH - Example: NH 3(aq) Faridah Hamat SASER 2008
- 5. Basicity of Acid Basicity of an acid is the maximum number of hydrogen ions that is produced when one molecule of an acid ionizes in water Monoprotic acid: Hydrochloric acid, HCl and nitric acid, HNO 3 . e.g : H Cl H + + Cl - Diprotic acid : Sulphuric acid, H 2 SO 4 e.g: H 2 SO 4 2H + + SO 4 2- Faridah Hamat SASER 2008
- 6. Cont…… Triprotic acid: Phosphoric acid, H 3 PO 4 e.g: H 3 PO 4 3H + + PO 4 3- Faridah Hamat SASER 2008
- 7. Physical Properties of Acid Acids have a sour taste Solution of acids has pH less than 7 Solution of acid change blue litmus paper to red. Aqueous solution of acids are electrolytes because the presence of freely moving ions (H + ) Faridah Hamat SASER 2008
- 8. Chemical Properties of Acid Acid + metal salt + hydrogen gas 2HCl (aq) + Mg (s) MgCl 2 (aq) + H 2 (g) Acid + base salt + water H 2 SO 4 (aq) + CuO (s) CuSO 4 (aq) + H 2 O(l) Acid + alkali salt + water HNO 3 + NaOH (aq) NaNO 3 + H 2 O Faridah Hamat SASER 2008
- 9. Cont….. Acid + carbonate metal salt + water + carbon dioxide 2HCl + CaCO 3 CaCl 2 + H 2 O + CO 2 Faridah Hamat SASER 2008
- 10. An acid shows its acidic properties only when it is dissolved in water. This is because without water, an acid still exits as molecules and there are no hydrogen ions, H + present. In the dry acid, the ions in the acid are fixed in the lattice positions. Faridah Hamat SASER 2008
- 11. Physical Properties of Alkali a bitter taste pH greater then 7 change red litmus paper to blue Aqueous solution of alkalis are electrolytes because the presence of freely moving ions. Faridah Hamat SASER 2008
- 12. Chemical Properties of Alkali Acid + alkali salt + water HNO3 + NaOH NaNO 3 + H 2 O Alkali + metal ion insoluble metal hydroxide 2OH - + Mg 2+ Mg(OH) 2 Alkali + ammonium salt salt + water + ammonia NaOH + NH 4 Cl NaCl + H 2 O + NH 3 Faridah Hamat SASER 2008
- 13. USES Faridah Hamat SASER 2008 Uses of acids Uses of bases and alkalis * Make industrial products such as paints, detergents, fertilizers. * Food preservative such as vinegar, citric acid and ascorbic acid. * Electrolyte in lead-acid accumulator. * Use as laboratory reagents * Make soaps, shampoos and detergents. * Make several of medicines, such as antacid and aspirin. * Use as laboratory reagents
- 14. Molarity (mol dm -3 ) = Number of Mole Volume, dm 3 Example: Calculate the molarity of 0.4 moles sulphuric acid in 250cm 3 solution. Solution : Number of mole = MV 1000 Molarity = number of mole x 1000 = 0.4 x 1000 250 250 = 1.6 mol dm -3 CONCENTRATION Faridah Hamat SASER 2008
- 15. PREPARED BY: PN. FARIDAH BINTI HAMAT SASER Faridah Hamat SASER 2008