Give the balanced reactions for the following:
(a) Sodium is dropped in water,
(b) Magnesium reacts with boiling water,
(c) Red hot ion reacts with steam,
(d) Iron reacts with dilute HCl.
a-Sodium being very reactive reacts vigorously with cold water which results with release of lot of heat along with flames.
2Na(s) +2H2O(l)----->2 NaOH (aq) + H2(gas ) + heat.
As the reaction is highly exothermic , the hydrogen gas produced in this reaction catches fire and burns causing little explosion.
Mg(s) + H2O(g)[steam] → MgO(s) + H2(g)
It can form Mg(OH)2 in case of higher concentration of water. But the reaction proceeds at slower rate.
We get hydrogen gas by reduction. Red hot iron reduces steam to hydrogen.
3Fe + 4H2O = Fe3O4 + 4H2
The other solid product is magnetite, Fe3O4, a mixed oxide (FeO.Fe2O3) of iron
dil.HCl reacts with Fe fillings to give H2 gas and FeCl2.
You may ask why not FeCl3 which is more stable.
H2 formed in the reaction is known for its strong reducing power, it reduces Fe3+toFe2+