SATHEE: pBlock ElementsII 1 Question 43

pBlock ElementsII 1 Question 43

43. The compound(s) which generate (s) $N_{2}$ gas upon thermal decomposition below $300^{\circ} C$ is (are)

(2018 Adv.)

(a) ${NH}_{4} {NO}_{3}$

(b) ${({NH}_{4})}_{2} {Cr}_{2} O_{7}$

(d) ${Mg}_{3} N_{2}$

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Answer:

Correct Answer: 43. (b,c)

Solution:

Among the given compounds, those which generate $N_{2}$ on thermal decomposition below $300^{\circ} C$ are ammonium dichromate i.e., ${({NH}_{4})}_{2} {Cr}_{2} O_{7}$ and barium azide or nitride i.e., $Ba {(N_{3})}_{2}$ . Reactions of their thermal decomposition are given below

(i) ${({NH}_{4})}_{2} {Cr}_{2} O_{7} \to_{Below 300^{\circ} C}^{⟶} N_{2} ↑ + {Cr}_{2} O_{3} + 4 H_{2} O$

It is an exothemic reaction with

$Δ H = - 429.1 \pm 3 kcal / mol .$

(ii) $Ba {(N_{3})}_{2} \to_{Around 160^{\circ} and above}^{Δ} Ba + 3 N_{2} ↑$

Ammonium nitrate $({NH}_{4} {NO}_{3})$ on heating below $300^{\circ} C$ gives $N_{2} O$ as

${NH}_{4} {NO}_{3} \to_{below 300^{\circ} C}^{⟶} N_{2} O + 2 H_{2} O$

However, on rapid heating or explosion

(i.e. above $300^{\circ} C$ ) it gives off nitrogen as

$2 {NH}_{4} {NO}_{3} \to_{or explosion}^{Rapid heating} 2 N_{2} + O_{2} + 4 H_{2} O$

Magnesium nitride $({Mg}_{3} N_{2})$ does not decompose at lower temperatures being comparatively more stable. Its thermal decomposition requires a minimum temperature of $700^{\circ} C$ and proceeds as

${Mg}_{3} N_{2} \overset{700 - 1500^{\circ} C}{⟶} 3 Mg + N_{2} ↑$

pBlock ElementsII 1 Question 43

43. The compound(s) which generate (s) $N_{2}$ gas upon thermal decomposition below $300^{\circ} C$ is (are)

Answer:

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pBlock ElementsII 1 Question 43

43. The compound(s) which generate (s) N2 gas upon thermal decomposition below 300∘C is (are)

Answer:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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43. The compound(s) which generate (s) $N_{2}$ gas upon thermal decomposition below $300^{\circ} C$ is (are)