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Explain the following reaction: 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. |
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Answer» a. A mixture of mono-and di-acid trimethylchloro silanes alongwith a small amount of tetramethyl silance is formed. `Si+CH_(3)Clunderset("373 K")overset("Cu powder")to CH_(3)SiCl_(3)+(CH_(3))_(2)SiCl_(2)+(CH_(3))_(3)SiCl+(CH_(3))_(4)Si` b. `SiO_(2)`, reacts with `HF` on heating to form silicon tetrafluoride which dissolves in HF to form hydroflourosilicic acid. `SiO_(2)+4HFto underset("tetrafluoride")underset("Silicon")(SiF_(4))+H_(2)O` `SiF_(4)+2HFto underset("(soluble)")underset("Hydrofluorosilicic acid")(H_(2)SiF_(6))` c.`CO+ZnOoverset(Delta)toZn+CO_(2)uarr` d. Hydrated alumina dissolves in aqueous `NaOH` solution to form sodium meta-aluminate. `underset("or bauxite")underset("alumina")underset("Hydrated")(Al_(2)O_(3).2H_(2)O_((s)))+NaOH_((aq))overset(Delta)tounderset("(soluble)")underset("meta-aluminate")underset("Sodium")(2NaAlO_(2))+3H_(2)O or Al_(2)O_(3).2H_(2)O_((s))+2NaOH_((aq))+H_(2)O_((l))overset(Delta)tounderset("Sodium tetrahydro-aluminate(III)")(2Na[Al(OH)_(4)]_((aq)))` |
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