Question

Carbon and oxygen combine in the ratio 3:8 by mass to form carbon dioxide. What mass of oxygen will be required to combine completely with 12g of Carbon?

Answer 1

$$\begin{gathered} \mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{C}=12\mathrm{g}\mathrm{and}\mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{O}=16\mathrm{g}. \\ \mathrm{So},\mathrm{Molecular}\mathrm{mass}\mathrm{of}\mathrm{Carbon}\mathrm{dioxide}\left({\mathrm{CO}}_2\right)=(12+(2\times 16\left)\right)=(12+32)=44\mathrm{g}. \\ 3:8 \end{gathered}$$

1. It is given that in carbon dioxide, carbon and oxygen combine in a ratio of 3:8.
2. That is for 3 parts of Carbon, 8 parts of oxygen are required to give one molecule of carbon dioxide.
3. So, For 1g of carbon, amount of oxygen required will be =$\frac{8}{3}g$.

Therefore, for 12g of Carbon, amount of Oxygen required will be $12\times \frac{8}{3}=32g$