REACTIVITY OF THE MAIN METALS
POTASSIUM
Reaction with water
When a small piece of potassium is added to water, it produces a hissing sound as it burns with a lilac flame. It also moves about quickly on the water surface.
Hydrogen gas is given out in the reaction. The resulting alkaline solution will turn red litmus blue because of the potassium hydroxide formed.
potassium + water è potassium hydroxide solution + hydrogen
4K(s) + 4H2O(l) → 4KOH (aq) + 2H2(g)
Reaction with oxygen
Potassium burns vigorously in oxygen, so only gentle heating is required to make it burn. It gives a lilac flame to produce an orange powder.
Potassium + oxygen → potassium oxide
K(s) + O2(g) → K2O(s)
Reaction with dilute acids
Potassium reacts with dilute acids explosively.
Potassium reacts with dilute hydrochloric acid to give potassium chloride and hydrogen gas.
Potassium + dilute hydrochloric acid → potassium chloride + hydrogen
2K(s) + 2HCl(aq) → 2KCl(aq) + H2(g)
Potassium reacts with dilute sulphuric acid to give potassium sulphate and hydrogen gas.
potassium + dilute sulphuric acid → potassium sulphate + hydrogen
2K(s) + H2SO4 (aq) → K2SO4(aq) + H2(g)
Potassium reacts with dilute nitric acid to give potassium nitrate and hydrogen gas.
potassium + dilute nitric acid è potassium nitrate + hydrogen
2K(s) + 2HNO3(aq) → 2KNO3(aq) + H2(g)
SODIUM
Reaction with water
When a small piece of sodium is added to water, it moves about on the water surface. Its size gradually becomes smaller.
Hydrogen gas is given out in the reaction. The resulting alkaline solution will turn red litmus blue because of the sodium hydroxide formed.
sodium + water → sodium hydroxide solution + hydrogen
4Na(s) + 4H2O(l) → 4NaOH(aq) + 2H2(g)
Reaction with oxygen
Sodium burns vigorously in oxygen, so only gently heating is required to make it burn. It gives a golden yellow flame to produce a white powder.
Sodium + oxygen → sodium oxide
4Na (s) + O2(g) → 2Na2O(s)
Reaction with dilute acids
Sodium may reacts with dilute acids explosively
Sodium reacts with dilute hydrochloric acid to give sodium chloride and hydrogen gas.
sodium + dilute hydrochloric acid → sodium chloride + hydrogen
2Na(s) + 2HCl(aq) → 2NaCl(aq) + H2(g)
Sodium reacts with dilute sulphuric acid to give sodium sulphate and hydrogen gas.
sodium + dilute sulphuric acid → sodium sulphate + hydrogen
2Na(s) + H2SO4(aq) → Na2SO4(aq) + H2(g)
Sodium reacts with dilute nitric acid to give sodium nitrate and hydrogen gas.
sodium + dilute nitric acid → sodium nitrate + hydrogen
2Na(s) + 2HNO3(aq) → 2NaNO3(aq) + H2(g)
CALCIUM
Reaction with water
When a small piece of calcium is added to water, it sinks to the bottom of the water. Colorless gas bubbles evolved at a moderate rate. Unlike potassium or sodium, this experiment is safe enough to capture the gas produces, which gives a “pop” sound with a burning splint, indicative of hydrogen gas.
A milky suspension is produced, as the white calcium hydroxide formed is only slightly soluble in water. However, the alkaline solution produced is still strong enough to turn red litmus to blue.
Calcium + water → calcium hydroxide + hydrogen
Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)
Reaction with oxygen
Calcium burns quite vigorously in oxygen and strong heating is required to make it burn. It gives a brick red flame to produce a white powder of calcium oxide.
Calcium + oxygen → calcium oxide
2Ca(s) + O2(g) → 2CaO(s)
Reaction with dilute acids
The following experiment should be carried out with care.
Calcium reacts with dilute hydrochloric acid to give calcium chloride and hydrogen gas.
calcium + dilute hydrochloric acid → calcium chloride + hydrogen
Ca(s) + 2HCl(aq) → CaCl2(aq) + H2(g)
Calcium reacts with dilute sulphuric acid to give calcium sulfate and hydrogen gas. Initial reaction is fast, but gradually slows down. This is because calcium sulfate is quite insoluble in water, which forms a protective layer on calcium and preventing the acid to react effectively with calcium.
Calcium + dilute sulphuric acid → calcium sulphate + hydrogen
Ca(s) + H2SO4(aq) → CaSO4(s) + H2(g)
Calcium reacts with dilute nitric acid to give calcium nitrate and hydrogen gas.
calcium + dilute nitric acid → calcium nitrate + hydrogen
Ca(s) + 2HNO3(aq) → Ca(NO3)2(aq) + H2(g)
MAGNESIUM
Reaction with cold water
Magnesium virtually has no reaction with cold water.
It reacts slowly with hot water to give hydrogen gas and white magnesium hydroxide, which is only slightly soluble in water.
Magnesium + water → magnesium hydroxide solution + hydrogen
Mg(s) + 2H2O(l) → Mg(OH)2(s) + H2(g)
Magnesium can react vigorously with steam to give an intense white light. Hydrogen gas and a white solid of magnesium oxide [image]
Hydrogen gas is given out in the reaction. The resulting alkaline solution will turn red litmus blue because of the magnesium hydroxide formed.
Magnesium + steam → magnesium oxide + hydrogen
Mg(s) + H2O (g) → MgO(s) + H2(g)
Reaction with oxygen
Strong heating is required to make magnesium burn in oxygen. Once the reaction starts, it gives an intense brilliant white flame to produce a white powder of magnesium oxide.
magnesium + oxygen → magnesium oxide
2Mg(s) + O2(g) → 2MgO(s)
Reaction with dilute acids
Magnesium reacts with dilute hydrochloric acid to give magnesium chloride and hydrogen gas.
magnesium + hydrochloric acid → magnesium chloride + hydrogen
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
- Magnesium reacts with dilute sulphuric acid to give magnesium sulphate and hydrogen gas.
magnesium + sulphuric acid → magnesium sulphate + hydrogen
Mg(s) + H2SO4 (aq) → MgSO4(aq) + H2(g)
Magnesium reacts with dilute nitric acid to give magnesium nitrate and hydrogen gas.
magnesium + nitric acid → magnesium nitrate + hydrogen
Mg(s) + 2HNO3(aq) → Mg(NO3)2(aq) + H2(g)
ALUMINUM
Reaction with water
Aluminium does not react with cold water.
Although aluminium reacts readily with steam to give aluminium oxide and hydrogen gas, the reaction does not always occur. This is due to a thin but strong layer of aluminium oxide being coated onto the metal, thus preventing it from the reaction.
aluminium + steam → aluminium oxide + hydrogen
2Al(s) + 3H2O(g) → Al2O3(s) + 3H2(g)
Reaction with oxygen
Strong heating is required to make aluminium powder burn in oxygen. Much heat is given out during the reaction and a white powder is formed.
aluminium + oxygen → aluminium oxide
4Al(s) + 3O2(g) → 2Al2O3(s)
Reaction with dilute acids
Aluminium reacts with dilute hydrochloric acid to give aluminium chloride and hydrogen gas.
aluminium + hydrochloric acid → aluminium chloride + hydrogen
2Al(s) + 6HCl (aq) → 2AlCl3 (aq) + 3H2(g)
Aluminium reacts with dilute sulphuric acid to give aluminium sulphate and hydrogen gas.
aluminium + sulphuric acid → aluminium sulphate + hydrogen
2Al(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3H2(g)
Aluminium reacts with dilute nitric acid to give aluminium nitrate and hydrogen gas.
aluminium + nitric acid → aluminium nitrate + hydrogen
2Al(s) + 6HNO3 (aq) → 2Al(NO3)3 (aq) + 3H2(g)
CARBON
CARBON
Reaction with oxygen
Strong heating is required to make carbon powder burns in oxygen. Carbon dioxide that subsequently formed can turn lime water (calcium hydroxide solution) milky.
carbon + oxygen → carbon dioxide
C(s) + O2(g) → CO2(g)
ZINC
Reaction with water
Zinc virtually has no reaction with cold water.
Zinc reacts with steam to give zinc oxide and hydrogen gas. The reaction occurs in a similar way as magnesium does, but less vigorous.
zinc + steam → zinc oxide + hydrogen
Zn(s) + H2O(g) → ZnO(s) + H2(g)
Reaction with oxygen
Strong heating is required to make zinc powder burn in oxygen. Much heat is given out during the reaction and a white powder is formed, which is yellow when hot and white when cold.
zinc + oxygen → zinc oxide
2Zn(s) + O2(g) → 2ZnO(s)
Reaction with dilute acids
Zinc reacts with dilute hydrochloric acid to give zinc chloride and hydrogen gas.
zinc + hydrochloric acid → zinc chloride + hydrogen
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
Zinc reacts with dilute sulphuric acid to give zinc sulphate and hydrogen gas.
zinc + sulphuric acid → zinc sulphate + hydrogen
Zn(s) + H2SO4 (aq) → ZnSO4(aq) + H2(g)
Zinc reacts with dilute nitric acid to give zinc nitrate and hydrogen gas.
Zinc + nitric acid → Zinc nitrate + hydrogen
Zn(s) + 2HNO3(aq) → Zn(NO3)2(aq) + H2(g)
IRON
Reaction with water
Iron virtually has no reaction with cold water.
Iron reacts with steam to give iron oxide and hydrogen gas. The reaction occurs in a similar way as magnesium does, but much less vigorous.
iron + steam → iron (II) iron (III) oxide + hydrogen gas
3Fe(s) + 4H2O(g) → Fe3O4 (s) + 4H2 (g)
* Fe3O4 = FeO.Fe2O3
Reaction with oxygen
Strong heating is required to make iron powder burn in oxygen. The reaction gives out a yellow showery sparks and produces a black solid.
iron + oxygen → iron (II) oxide, iron (III) oxide
3Fe(s) + 2O2(g) → Fe3O4(s)
Reaction with dilute acids
Iron reacts with dilute hydrochloric acid to give iron chloride and hydrogen gas.
iron + hydrochloric acid → iron chloride + hydrogen
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)
Iron reacts with dilute sulphuric acid to give iron sulphate and hydrogen gas.
iron + sulphuric acid → iron sulphate + hydrogen
Fe(s) + H2SO4 (aq) → FeSO4(aq) + H2(g)
Iron reacts with dilute nitric acid to give Iron nitrate and hydrogen gas.
iron + nitric acid → iron nitrate + hydrogen
Fe(s) + 2HNO3(aq) → Fe(NO3)2(aq) + H2(g)
LEAD
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COPPER
Reaction with water
Copper does not react with water.
Reaction with oxygen
On strong heating, copper forms into a black solid of copper oxide.
copper + oxygen �> copper(II) oxide
2Cu(s) + O2(g) �> 2CuO(s)
Reaction with dilute acids
Copper usually does not react with most cold, dilute acids. However, it will react with hot, concentrated sulfuric acid and can react with both dilute and concentrated nitric acid.