Question

In an experiment, pure carbon monoxide was passed over red-hot copper oxide. $C{O}_2,$ 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

Answer: 12

According to the reaction,
$C{u}_{2}O+CO\to C{O}_2+2Cu$
With respect to mole ratio,
$1molofC{u}_{2}Oproduces1molofC{O}_2$
Molar mass of $C{u}_{2}O=143gram$
Molar mass of $C{O}_2=44gram$
$143gramC{u}_{2}Oproduces44gramofC{O}_{2}0.3232gramC{u}_{2}Owillproduce=\frac{44\times 0.3232}{143}=0.099gramC{O}_2$ .
Now, calculating moles of carbon dioxide,
$moles=\frac{weight}{molecularmass}moles({\left(CO\right)}_2)=\frac{0.099}{44}=\mathrm{0.00225.}$
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, $44gramC{O}_2$ contains $12gmC$
So, $0.099gramC{O}_2$ will contain = $\frac{12\times 0.099}{44}=0.027gram(C)$ .
$0.00225molesofcarbon=0.027gram1mol=\frac{0.027}{0.00225}=12gram$
Thus, the atomic weight of carbon is $12gram$ .