what is the efficiency of an engine that dies 288 J of work and exhausts 72 J of heat while taking 360 J of heat?
1 answer:
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Answer : The correct option is, (B) -5448 kJ/mol
Explanation :
First we have to calculate the heat required by water.
where,
q = heat required by water = ?
m = mass of water = 250 g
c = specific heat capacity of water =
= initial temperature of water = 293.0 K
= final temperature of water = 371.2 K
Now put all the given values in the above formula, we get:
Now we have to calculate the enthalpy of combustion of octane.
where,
= enthalpy of combustion of octane = ?
q = heat released = -81719 J
n = moles of octane = 0.015 moles
Now put all the given values in the above formula, we get:
Therefore, the enthalpy of combustion of octane is -5448 kJ/mol.