Question

Heating of ammonium dichromate produces:
a.) ${\text{N}}{{\text{H}}_{\text{3}}}{\text{, C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{3}}}{\text{ and }}{{\text{H}}_{\text{2}}}{\text{O}}$
b.) ${{\text{N}}_{\text{2}}}{\text{, C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{3}}}{\text{ and }}{{\text{H}}_{\text{2}}}{\text{O}}$
c.) ${\text{NO, Cr}}{{\text{O}}_{\text{3}}}{\text{ and }}{{\text{H}}_{\text{2}}}{\text{O}}$
d.) ${{\text{N}}_{\text{2}}}{\text{O, Cr}}{{\text{O}}_{\text{3}}}{\text{ and }}{{\text{H}}_{\text{2}}}{\text{O}}$

Answer 1

Hint: When heated, Ammonium dichromate decomposes and produces orange sparks and an effect that looks like a miniature volcanic eruption. The process of heating and decomposition of Ammonium dichromate is also known as the volcano effect.

Complete step-by-step answer:
When ammonium dichromate is heated, its decomposition gives off orange sparks. It also throws green coloured chromium (III) oxide crystals into the air which looks like a miniature volcanic eruption. The chromium (III) oxide crystals produced by the so-called volcanic eruption when ammonium dichromate is heated, is ‘fluffier’ than the ammonium dichromate crystals itself. A lot of the mass of the ammonium dichromate is released as water vapour into the air and the product grows in volume. A large amount of Nitrogen gas is also formed during the reaction. The reaction of Ammonium dichromate when heated is a redox reaction in which chromium is reduced from its + 6 oxidation state in dichromate to + 3 Oxidation state in chromium trioxide. With the formula given below, we can see that on heating ammonium dichromate, it decomposes into chromium (III) oxide crystals, nitrogen gas and water vapour.

${{\text{(N}{{\text{H}}_{\text{4}}}\text{)}}_{\text{2}}}\text{C}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}}\left( \text{s} \right)\text{ }\!\!~\!\!\text{ }\xrightarrow{{}}\text{ C}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{3}}}\left( \text{s} \right)\text{ }\!\!~\!\!\text{ + }\!\!~\!\!\text{ }{{\text{N}}_{\text{2}}}\left( \text{g} \right)\text{ }\!\!~\!\!\text{ + }\!\!~\!\!\text{ 4}{{\text{H}}_{\text{2}}}\text{O}\left( \text{g} \right)$
Hence, heating of ammonium dichromate produces ${{\text{N}}_{\text{2}}}{\text{, C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{3}}}{\text{ and }}{{\text{H}}_{\text{2}}}{\text{O}}$.
Therefore, Option B is the correct option.

Note: Reducing agent loses electrons and is oxidized while an oxidizing agent gains electrons and is reduced. This is the basis of a Redox reaction. In a Redox reaction, both oxidation and reduction occurs in the same chemical reaction. The heating of ammonium dichromate is a prime example of one such redox reaction.