| 6.4 |
Chemical Properties of Acids and Alkalis |
Chemical properties of acids
- Acid tastes sour
- Corrosive
- Turns blue litmus paper red
- The pH value is less than 7
The reaction of an acid with a base produces salt and water
| Reaction of hydrochloric acid with sodium hydroxide |
| \(HCl(aq) + NaOH(aq) \rightarrow NaCl(aq) + H_2O(l)\) |
The reaction of an acid with a reactive metal produces salt and hydrogen gas
| Reaction of hydrochloric acid with zinc |
| \(2HCl(aq) + Zn(s) \rightarrow ZnCl_2(aq) + H_2(g)\) |
The reaction of an acid with a metal carbonate produces salt, water and carbon dioxide
| Reaction of hydrochloric acid with calcium carbonate |
| \(2HCl(aq) + CaCO_3(s) \rightarrow CaCl_2(aq) + H_2O(l)+ CO_2(g)\) |
Chemical properties of alkalis
- Alkali is bitter in taste and feels soapy.
- Turns red litmus paper blue
- The alkali has a pH value of more than 7
- Alkali reacts with an acid to produce salt and water.
- When alkali is heated with ammonia salt, it produces ammonia gas.
The reaction of alkali with an ammonium salt produces salt, water and ammonia gas
| Reaction of potassium hydroxide with ammonium chloride |
| \(KOH(aq) + NH_4Cl(aq) \rightarrow KCl(aq) + H_2O(l) + NH_3(g)\) |
The reaction of alkali with a metal ion produces insoluble metal hydroxide and cation of the alkali
| Reaction of sodium hydroxide with magnesium ion |
| \(2NaOH(aq) + Mg^{2+}(aq) \rightarrow Mg(OH)_2(aq) + 2Na^+(aq)\) |
