2
Question Question 6
State what is meant by 'reactivity series of metals'. With reference to -
(a) Water
(b) Acids
explain with suitable examples how the reactivity of the metals could be differentiated.
Reactivity series of metals is a series of arrangement of metals in decreasing order of their chemical reactivity. Metal reactivity series is listed below:
| Activity Series |
|---|
| K |
| Na |
| Ca |
| Mg |
| Al |
| Zn |
| Fe |
| Pb |
| *[H] |
| Cu |
| Hg |
| Ag |
| Pt |
| Au |
Differentiating reactivity of the metals with reference to Water & Acids:
| Reaction with | Metals | Observation | Equation |
|---|---|---|---|
| Water | K & Na | React violently with cold water | 2K + 2H2O ⟶ 2KOH + H2 |
| Ca | Reacts less vigorously with cold water | Ca + 2H2O ⟶ Ca(OH)2 + H2 | |
| Mg to Fe | React smoothly with water [steam] | 3Fe + 4H2O ⇌ Fe3O4 + 4H2 | |
| Below [H] | Do not react with water or steam displacing hydrogen from it. | ||
| Acids | K & Na | React explosively with HCl or dil. H2SO4 | 2K + 2HCl ⟶ 2KCl + H2 |
| Ca to Fe | React less vigorously with decreasing vigour with dil. HCl or dil. H2SO4 | Ca + 2HCl ⟶ CaCl2 + H2 | |
| Below [H] | Do not react with dil. acids, displacing hydrogen from it. |