Question

If LPG cylinder contains a mixture of butane and isobutene, then the amount of oxygen that would be required for combustion of 1kg of it will be:
(A) 1.8kg
(B) 2.7kg
(C) 4.5kg
(D) 3.58kg

Answer 1

Combustion is a chemical process in which a substance reacts rapidly with oxygen and gives off heat. The original substance is called the fuel, and the source of oxygen is called an oxidizer. The fuel can be a solid, liquid or gas. Further, liquid petroleum gas is a flammable mixture of hydrocarbon gases used as a fuel in heating appliances, vehicles etc.

Complete step by step answer:
Combustion can be considered as the oldest technology of mankind and one of the most discoveries or inventions. In this process, when substances react spontaneously with oxygen, giving off heat and light, then the heat released fuels the process and thus makes the reaction violent and rapid
Now, in the given question, the LPG cylinder contains a mixture of butane and isobutene. Let’s find out the amount of oxygen required for combustion of $1kg$.
Now, the standard enthalpy of combustion of butane ${C_4}{H_{10}}$, representing the combustion of 1 mole of butane in the presence of oxygen, can be represented as:
${C_4}H{}_{10}(g) + \dfrac{{13}}{2}{O_2}(g) \to 4C{O_2}(g) + 5{H_2}O(l)$
Now, 58kg of ${C_4}{H_{10}}$ according to the reaction requires:
$\dfrac{{13}}{2} \times 32 = 208kg$ of ${O_2}$
Now, oxygen required for 1kg of butane will be $= \dfrac{{208}}{{58}}$
$= 3.58kg$

Hence, option D is correct.

Note:
Thermal energy derived from the combustion of either fossil fuels such as coal or oil or from renewable fuels such as firewood is extracted for a range of uses, such as cooking, power generation or industrial or domestic heating. Combustion is also the only process actually used to fuel rockets. Further, isobutene shares the same molecular formula as normal butane, but the shape of its molecule makes isobutene far more superior in terms of vapor pressure.