Question

In an experiment, pure carbon monoxide was passed over red-hot copper oxide. $CO_{2},$ so produced, weighed $0.88g$ and the weight of copper oxide was reduced by $0.3232g$ . Calculate the atomic weight of carbon. [ Take molar mass of carbon dioxide = $44g$ ]

Answer 1

According to the reaction,
$Cu_{2}O+CO \rightarrow CO_{2}+2Cu$
With respect to mole ratio,
$1molofCu_{2}Oproduces1molofCO_{2}$
Molar mass of $Cu_{2}O=143gram$
Molar mass of $CO_{2}=44gram$
$143gramCu_{2}Oproduces44gramofCO_{2}0.3232gramCu_{2}Owillproduce=\frac{44 \times 0 . 3232}{143}=0.099gramCO_{2}$ .
Now, calculating moles of carbon dioxide,
$moles=\frac{weight}{molecular mass}moles\left(\right.\left(CO\right)_{2}\left.\right)=\frac{0 . 099}{44}=0.00225.$
As per the reaction, one mole of carbon dioxide has one mole of carbon so moles of carbon will be same as moles of carbon dioxide.
$moles\left(C\right)=0.00225$ .
Now, $44gramCO_{2}$ contains $12gmC$
So, $0.099gramCO_{2}$ will contain = $\frac{12 \times 0 . 099}{44}=0.027gram\left(\right.C\left.\right)$ .
$0.00225molesofcarbon=0.027gram1mol=\frac{0 . 027}{0 . 00225}=12gram$
Thus, the atomic weight of carbon is $12gram$ .