Butane (C4H10(g), deltaHf =-125.6 kJ/mol reacts with oxygen to produce carbon dioxide (CO2 delta Hf =-393.5 kJ/mol)

The given question is incomplete. The complete question is:

Butane , Hf = –125.6 kJ/mol) reacts with oxygen to produce carbon dioxide ( , Hf = –393.5 kJ/mol ) and water , Hf = –241.82 kJ/mol) according to the equation below. What is the enthalpy of combustion (per mole) of ?

-2657.5 kJ

Explanation:

The balanced chemical reaction is,

The expression for enthalpy change is,

where,

n = number of moles

(as heat of formation of substances in their standard state is zero

Now put all the given values in this expression, we get

Therefore, the enthalpy of combustion per mole of butane is -2657.5 kJ

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.