Question
How much oxygen is required for complete combustion of $$560\,g$$ of ethene ?
A.
$$6.4\,kg$$
B.
$$1.92\,kg$$
C.
$$2.8\,kg$$
D.
$$9.6\,kg$$
Answer :
$$1.92\,kg$$
Solution :
\[\underset{28\,g}{\mathop{{{C}_{2}}{{H}_{4}}}}\,+\underset{\begin{smallmatrix}
3\times 32 \\
=96\,g
\end{smallmatrix}}{\mathop{3{{O}_{2}}}}\,\to 2C{{O}_{2}}+2{{H}_{2}}O\]
$$28\,g\,\,{\text{of}}\,\,{C_2}{H_4}\,\,{\text{requires}}\,\,96\,g\,\,{\text{of}}\,\,{O_2}$$
$$560\,g\,\,{\text{of}}\,\,{C_2}{H_4}\,\,{\text{requires}}\,\frac{{96}}{{28}} \times 560$$ $$ = 1920\,g\,\,{\text{or}}\,\,1.92\,kg\,\,{\text{of}}\,\,{O_2}$$