(a) When carbon dioxide is passed over red hot carbon, carbon monoxide is produced according to the equation :

CO₂ + C ⟶ 2CO

What volume of carbon monoxide at S.T.P. can be obtained from 3 g of carbon?

(b) 60 cm³ of oxygen was added to 24 cm³ of carbon monoxide and mixture ignited. Calculate:

(i) volume of oxygen used up and

(ii) Volume of carbon dioxide formed.

$\begin{matrix} \text{CO}_2 & + &\text{C} & \longrightarrow & 2\text{CO} \\ 1\text{ vol.} & : & 1 \text{ vol.} & \longrightarrow & 2 \text{ vol.} \\ \end{matrix}$

[By Gay Lussac's law]

1 Vol. of C produces 2V of CO

12 g of C produces 2 x 22.4 L of CO

∴ 3 g of C will produce $\dfrac{2 \times 22.4}{12}$ x 3

= 11.2 L of CO

(b)

$\begin{matrix} \text{O}$2 & + &\text{2CO} & \longrightarrow & 2\text{CO}2 \\ 1\text{ vol.} & : & 2 \text{ vol.} & \longrightarrow & 2 \text{ vol.} \\ \end{matrix}

(i) 2 Vol. of CO requires 1 Vol. of oxygen

∴ 24 cm³ CO will require $\dfrac{1}{2}$ x 24

= 12 cm³ of oxygen

(ii) 2 Vol. of CO gives 2 vol. of CO₂

∴ 24 cm³ of CO will give 24 cm³ of CO₂