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.

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Solution

a-Sodium being very reactive reacts vigorously with cold water which results with release of lot of heat along with flames.
2Na(s) +2 $H_{2} O$ (l)----->2 NaOH (aq) + $H_{2}$ (gas ) + heat.
As the reaction is highly exothermic , the hydrogen gas produced in this reaction catches fire and burns causing little explosion.

b-

Mg(s) + $H_{2} O$ (g)[steam] → MgO(s) + $H_{2}$ (g)

It can form $M g (O H)_{2}$ in case of higher concentration of water. But the reaction proceeds at slower rate.

c-

We get hydrogen gas by reduction. Red hot iron reduces steam to hydrogen.

3Fe + 4 $H_{2} O$ = $F e_{3} O_{4}$ + 4 $H_{2}$

The other solid product is magnetite, Fe3O4, a mixed oxide (FeO.Fe2O3) of iron

d-
dil.HCl reacts with Fe fillings to give $H_{2}$ gas and $F e C l_{2}$ .
You may ask why not $F e C l_{3}$ which is more stable.
H2 formed in the reaction is known for its strong reducing power, it reduces $F e^{3} + t o F e^{2} +$

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Similar questions

From the metals: copper, iron,magnesium, sodium, and zinc, select a different metal in each case which:

(a) does not react with dilute hydrochloric acid,

(b) can form $2^{+}$ and $3^{+}$ ions,

(d) does not react with cold water but reacts with steam when heated.

(e) Arrange the above metals in their decreasing order of reactivity.

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