Question

Reactions of nitric acid with copper powder is initially not fast but it becomes rapid after some time because

• A. Auto-catalysis takes place due to formations of $\mathrm { NO } _ { 2 } ^ { - }$ions.
• B. Partial catalysis takes places due to formations of copper nitrate
• C. Negative catalysis takes places due to formations of $\mathrm { H } ^ { + }$ions
• D. Catalyst poisoning takes place after some time in the reactions.

Answer 1

Answer: (A)

Auto-catalysis takes place due to formations of $\mathrm { NO } _ { 2 } ^ { - }$ions.

Answer 2

$3 \mathrm { Cu } + 8 \mathrm { HNO } _ { 3 } \rightarrow 3 \mathrm { Cu } \left( \mathrm { NO } _ { 3 } \right) _ { 2 } + 4 \mathrm { H } _ { 2 } \mathrm { O } + 2 \mathrm { NO }$

$2 \mathrm { NO } + \mathrm { H } _ { 2 } \mathrm { O } + \mathrm { O } \rightarrow 2 \mathrm { H } ^ { + } + 2 \mathrm { NO } _ { 2 } ^ { - }$(auto- catalyst)