Preparation of CO : Lab method : Pure CO is prepared by dehydration of formic acid or oxalic acid with concentrated $\mathrm{H}_2\mathrm{SO}_4$ at 373 K. HCOOH $\xrightarrow[\text{conc. H}_2\mathrm{SO}_4]{373\,\mathrm{K}}$ CO + $\mathrm{H}_2\mathrm{O}$ Industrial method : CO is prepared by the passage of steam over hot coke. The mixture of CO and $\mathrm{H}_2$ thus, produced is known as water gas or synthesis gas. $\mathrm{C(s)}+\mathrm{H_2O(g)}$ $\xrightarrow{473-1273\,\mathrm{K}}$ $\underset{\text{Water gas}}{\mathrm{CO(g)}+\mathrm{H_2(g)}}$ When air is used instead of steam, a mixture of CO and $\mathrm{N}_2$ is produced, which is called producer gas. $2\mathrm{C(s)}+\mathrm{O_2(g)}+\mathrm{N_2(g)}$ $\xrightarrow{1273\,\mathrm{K}}$ $\underset{\text{Producer gas}}{2\mathrm{CO(g)}+\mathrm{N_2(g)}}$ Preparation of $\mathrm{CO}_2$ : Lab method : In the laboratory it is conveniently prepared by the action of dilute HCl on calcium carbonate. $\mathrm{CaCO_3(s)}+2\mathrm{HCl(aq)}$ → $\mathrm{CaCl_2(aq)}+\mathrm{CO_2(g)}+\mathrm{H_2O(l)}$ Industrial method : When lime is manufactured by the calcination of limestone $(\mathrm{CaCO_3})$, carbon dioxide is obtained as a by product. $\mathrm{CaCO_3}$ → $\mathrm{CaO}+\mathrm{CO_2}$