Question

Explain the following reactions.
(A) Silicon is heated with methyl chloride at high temperature in the presence of copper.
(B) Silicon dioxide is treated with hydrogen fluoride.
(C) CO is heated with ZnO.
(D) Hydrated alumina is treated with aqueous NaOH solution.

Answer 1

Hint: We will write down the reaction for each part respectively as given in the question. We will explain the reactions that we have considered as well in order to understand better.

Complete step by step solution:
(A) A class of organosilicon polymers called methyl substituted chlorosilanes is formed when silicone is reacted with methyl chloride in the presence of copper (catalyst) at a temperature of around 537 K-
Copper, in this reaction will work as a catalyst.
$\Rightarrow 2C{H_3}Cl + Si\xrightarrow[{Cu}]{{HighTemp}}{\left( {C{H_3}} \right)_2}SiC{l_2}$
It is not necessary that the product formed will be ${\left( {C{H_3}} \right)_2}SiC{l_2}$. The above reaction can also give products such as $\left( {C{H_3}} \right)SiC{l_3}$, $Si{\left( {C{H_3}} \right)_4}$ or ${\left( {C{H_3}} \right)_3}SiCl$.

(B) If silicone dioxide $\left( {Si{O_2}} \right)$ is heated by fluoride $\left( {HF} \right)$ hydrogen it forms tetrafluoride silicone $\left( {Si{F_4}} \right)$. The Si-O bond is typically a strong bond, and even at high temperatures is resistant to an attack by halogens and most acids. Yet it can be attacked by $\left( {HF} \right)$.
$\Rightarrow Si{O_2} + 4HF \to Si{F_4} + 2{H_2}O$
If $Si{F_4}$ formed during this reaction gives the product of hydrofluorosilicic acid, if reacted with HF further.
$\Rightarrow Si{F_4} + 2HF \to {H_2}Si{F_6}$

(C) $ZnO$ is reduced to $Zn$ as $CO$ interacts with $ZnO$. $CO$ serves as a reducing agent.
$\Rightarrow ZnO\left( s \right) + CO\left( g \right)\xrightarrow{\Delta }Zn\left( s \right) + C{O_2}\left( g \right)$

(D) Hydrated alumina disintegrates in the sodium hydroxide due to the formation of sodium meta-aluminate, when hydrated alumina is added to the sodium hydroxide.
$\Rightarrow A{l_2}{O_3}.2{H_2}O + 2NaOH \to 2NaAl{O_2} + 3{H_2}O$

Note: In chemistry, a catalyst, any material that increases the reaction rate without consuming itself. Obviously, enzymes are naturally occurring catalysts for various important biochemical reactions.