Question

Which of the following reactions gives CO as their major product?

• A. only 3
• B. 1, 2, 3
• C. 2, 3
• D. 1, 2

Answer 1

The correct option is D 1, 2

1. Oxidation of carbon in limited supply of oxygen or air yield carbon monoxide. This is called incomplete combustion.
$2C\left(s\right)+\text{limited supply of}{O}_2\left(g\right)\stackrel{\Delta }{⟶}2CO\left(g\right)$

2. Dehydration of formic acid with concentrated $H_{2}S{O}_4$ at 373 K yield CO and water.
$HCOOH\left(l\right)\stackrel{con.H_{2}S{O}_4,\Delta }{⟶}CO\left(g\right)+H_{2}O\left(l\right)$

3. This reaction is an industrial preparation method of CaO. $C{O}_2$ is released during the reaction.
$CaC{O}_3\left(s\right)\to CaO\left(s\right)+C{O}_2\left(g\right)$

4. This reaction is the complete combustion of carbon in presence of excess oxygen. This gives $C{O}_2$ as the major product.
$C\left(s\right)+O_2\left(g\right)\stackrel{\Delta }{⟶}C{O}_2\left(g\right)$
thus reaction 1 and 2 give CO as a major product. Hence, option d is correct.

THEORY
Preparation:
1. Direct oxidation of C in a limited supply of oxygen or air
$2C\left(s\right)+O_2\left(g\right)\stackrel{△}{\to }2CO\left(g\right)$
2. By dehydrating formic acid with concentrated $H_{2}S{O}_4$ at 373K
$HCOOH\left(l\right)\underset{conc.H_{2}S{O}_4}{\overset{373K}{\to }}CO\left(g\right)+H_{2}O\left(I\right)$
3. By the passage of steam over hot coke.
$C\left(s\right)+H_{2}O\left(g\right)\stackrel{473-1273K}{\to }\underset{Waterorsynthesisgas}{C}O\left(g\right)+H_2\left(g\right)$
4. If air is used instead of steam, a mixture of CO and $N_2$ is produced.
$2C\left(s\right)+O_2\left(g\right)+4N_2\left(g\right)\stackrel{1273K}{\to }\underset{Producergas}{2CO\left(g\right)+4N_2}\left(g\right)$

• Water gas and producer gas are very important industrial fuels.
• CO in water gas or producer gas can undergo further combustion forming $C{O}_2$ with the liberation of heat.