Question

One litre of $O_2$ at NTP reacts with 3 times the volume of CO at NTP. Calculate volume of $C{O}_2$ formed.

Answer 1

Volume of reactants is given and volume of product is asked. So, volume-volume problem
Start by balancing the reaction
2CO + $O_2$ $\to$ 2$C{O}_2$
$\therefore$ 1 mole of $O_2$ $\approx$ 2 moles of CO
From gas laws, because the gases are at same T and P,
1 L of $O_2$ $\approx$ 2 L of CO
$\therefore$ 1 L of $O_2$ will react with 2 L of CO to yield 2L of $C{O}_2$.The remaining 1 L of CO will be left as unreacted reactant.