Question

(a)
Write chemical equations for the reaction taking place wher:
(0) Magnesium reacts with dilute HNO,
(I) Calcium reacts with water
() Zinc reacts with dilute hydrochloric acid.
balance the following chemical equations and state whether they are exothermic or endothermic.
0 Na + H204 NaOH + H,
() FeSO, → Fe 0, +SO, - so,​

Answer 1

i)

Magnesium reacts with dilute $\sf HNO_3$ to liberate hydrogen gas.

$\sf Mg(s) + 2HNO_3(aq) \rightarrow Mg(NO_3)_2(aq) + H_2(g)$

★ It is notable that only magnesium and manganese are able to liberate hydrogen gas after reacting with nitric acid. This is so because nitric acid is a very strong oxidising agent which oxidises the hydrogen produced to water and itself gets reduced to any of the nitrogen oxide after reacting with any other metal.

ii) Calcium reacts with water to form calcium hydroxide (slaked lime) and liberates hydrogen gas.

$\sf Ca + 2H_2O \rightarrow Ca(OH)_2 + H_2$

iii) Zinc reacts with hydrochloric acid to form zinc chloride and liberates hydrogen gas.

$\sf Zn + 2HCl \rightarrow ZnCl_2 + H_2$

$\rule{200}2$

Balanced chemical equation:

$\sf 2Na + 2H_2O \rightarrow 2NaOH + H_2$

Given reaction is exothermic as heat is released in a tremendous amount, causing hydrogen gas to burn.

$\sf 2FeSO_4 \rightarrow Fe_2O_3 + SO_2 + SO_3$

Given reaction is endothermic reaction because heat is provided for the reaction to happen.

Answer 2

Answer:

Following are the balanced chemical equations.

(a) Magnesium reacts with dilute $HNO_{3}$

$\;\;\;\;\;\;\sf{Mg+2HNO_{3} \rightarrow Mg{(N{O}_{3})}_{2}+H_{2}}$

(b) Calcium reacts with water.

$\;\;\;\;\;\;\sf{Ca+2H_{2}O \rightarrow Ca{(OH)}_{2}+H_{2}}$

(c)Zinc reacts with dilute hydrochloric acid.

$\;\;\;\;\;\;\sf{Zn + 2HCl \rightarrow Zn{Cl}_{2} + H_{2}}$

All of these are exothermic reactions i.e, liberate heat energy.

Further, balanced chemical equation are:-

(i) Exothermic reaction

$\;\;\;\;\;\;\sf{2Na + 2H_{2}O \rightarrow 2NaOH + H_{2}}$

(ii) Endothermic reaction

$\;\;\;\;\;\;\sf{2FeSO_{4} \rightarrow {Fe}_{2}O_{3} + SO_{2} + SO_{3}}$