1. Many reactive metals form salts when reacted with acids 2. Displacement reaction ( X Neutralisation reaction) 3. When Metal and Acid react > Salt and Hydrogen gas is formed 4. Only work for metals more reactive than hydrogen (But Aluminium doesn’t work because the impermeable layer aluminium oxide make it resistant to attack by acid) 5. Metals below hydrogen don’t react (e. g. copper, silver) & Metals at top of the reactivity series is never added to acid because they are too dangerous (e. g. sodium, potassium) Acid + Metal > a Salt + Hydrogen.
E. G. 2HCL(aq) + Mg(s) > MgCL2(aq) + H2(g) Hydrochloric Acid + Magnesium > Magnesium Chloride + Hydrogen Method 2 : Acid + Insoluble Base 1. Neutralisation reaction 2. When Acid and Base react > Salt and Water is formed 3. The salt made depends on the acid used and the metal in the base/alkali – (e. g. Nitric acid always make nitrate, Sulfur acid always make sulfate, Hydrochloric acid always make chloride) – (e. g. Base contain Sodium ions always make sodium salt, base contain Potassium ions always make potassium salt).
Bases Soluble Insoluble – Sodium, Potassium, Calcium Hydroxides & Calcium Oxides – Ammonia THEY ARE ALKALIS All other Oxides & Hydroxides (USE INSOLUBLE BASES IN THIS METHOD) Acid + Base > a Salt + Water E. G. 6HCL(aq) + Fe2O3(s) > 2FeCL3(aq) + 3H2O(l) Hydrochloric Acid + Solid Iron(III) Oxide > Iron(III)Chloride Solution + Water Method 3 : Acid + Alkali (Soluble Base) 1. Neutralisation reaction (Titration) 2. An indicator can be used (Neutralisation Point is when the indicator changes colour) 3.
The solution of the weakly alkaline solution is evaporated to form a saturated solution and then it is left to crystalise Neutralisation – H+(aq)ions reacting with OH-(aq) ions to form water – H+(aq) + OH-(aq) > H2O (l) Acid + Base > a Salt + Water E. G. HNO3(aq) + NH4+(aq) > NH4NO3(aq) + H20(l) Nitric Acid + Ammomia Solution > Ammonium Nitrate + Water Method 4 : Precipitation to make Insoluble Salt 1. Insoluble salt can be made by reacting 2 solutions of soluble salts to produce a precipitate (insoluble solid) 2. Precipitation reaction.
3. We need to know about the solubility of salt to decide whether a salt in soluble/insoluble Salts Soluble Insoluble All sodium, potassium, ammonium salts All other Carbonates Nitrates Most Chlorides, Bromides & Iodides Silver and Lead Chlorides, Bromides & Iodides Most Sufates Calcium & Barium Sulphate AZ(aq) + BY(aq) > AY(s) + BX(aq) * AX, BY, BX are soluble(aq) & AY is insoluble(s) E. G. Pb(NO3)2(aq) +2KL(aq) > Pbl2(s) + 2KNO3(aq) Lead Nitrate Solution + Potassium Iodide Solution > Lead Iodide Precipitate + Potassium Nitrate Solution.