Question

How many moles of isooctane must be burned to produce 100 kJ of heat under standard state conditions? Show all of your work.

Answer 1

According to Prosen and Rossini, 1945, the standard heat of combustion of isooctane is -5461.3 kJ/mol. The negative sign is just to depict that there was a release of energy. Thus, to produce 100 kJ energy,

100 kJ ÷ 5461.3 kJ/mol isooctane = 0.0183 moles isooctane.

0.0183 moles of isooctane must be burned.

I hope I was able to answer your question J

Answer 2

Answer:

$mol_{isooct}= 0.0183 mol$

Explanation:

Hi, to calculate the moles needed for that energy requirement, first you need to understand the combustion reaction:

$C_8H_1_8 + 25/2 O_2 \longrightarrow 8 CO_2 + 9 H_2O$

Now, you need the heat of reaction. You can either search for it in tables or calculate it from the heats of formation.

For isooctane: $\Delta H_{comb}=-5450 kJ/mol$

The last step is just a simple calculation:

$mol_{isooct}=\frac{100kJ}{5450kJ/mol}$

$mol_{isooct}= 0.0183 mol$