In the following reaction for the preparation of gold sol, $a, b, c, x, y$ and $z$ are $a \mathrm{AuCl}_3+b…
In the following reaction for the preparation of gold sol, $a, b, c, x, y$ and $z$ are $a \mathrm{AuCl}_3+b \mathrm{HCHO}+c \mathrm{H}_2 \mathrm{O} \longrightarrow x \mathrm{Au}$ (sol) $+y \mathrm{HCO}_2 \mathrm{H}+z \mathrm{HCl}$
$a=2, b=3, c=3, x=2, y=3, z=6$
$a=2, b=3, c=2, x=2, y=3, z=4$
$a=2, b=2, c=2, x=2, y=2, z=4$
$a=3, b=2, c=2, x=3, y=2, z=6$
Solution
Gold sol is commercially prepared by Bredig's arc method.
$\begin{aligned} 2 \mathrm{AuCl}_3+3 \mathrm{HCHO}+3 \mathrm{H}_2 \mathrm{O} \longrightarrow & 2 \mathrm{Au} \text { (gold) } \\ & +3 \mathrm{HCO}_2 \mathrm{H}+6 \mathrm{HCl}\end{aligned}$