Question

heat of combustion of C2H4 is -337K.Cal.If 5.6 lit O2 is used at Stp in the combustion, heat liberated is K.Cal

Answer 1

Answer: 28.08 kcal

Explanation: The balanced combustion reaction is,:

$C_2H_4+3O_2\rightarrow 2CO_2+2H_2O$

For 1 mole of $C_2H_4$ heat released is 337 kcal

As can be seen from the given balanced equation, 1 mole of ethene reacts with 3 moles of Oxygen.

1 mole of any gas occupies 22.4 Liters at STP.

Thus 3 moles of  $O_2$ occupies $22.4\times {3}=67.2 L$

If 67.2 Liters of $O_2$ release energy = 337 kcal

5.6 Liters of $O_2$ release energy $=\frac{337kcal}{67.2L}\times {5.6L}= 28.08kcal$