CH4(g)+2O2(g)→CO2(g)+2H2O(l) ; T=27oC=300K
At constant pressure
ΔH=ΔU+ΔnRT
Rise in temperature of the system = 0.5oC=0.5K
Heat released to the system =−CpΔT=−17.7kJK×0.5K=−8.85kJ
0.16 g of methane =0.1616 mole=0.01 mole of methane (molecular weight of methane =16 g)
ΔU=−8.850.01=−885kJmole−1
Δn= moles of gaseous products − moles of gaseous reactants
Δn=1−(1+2)=−2
R=8.313Jmole−1K−1=8.313×10−3kJmole−1K−1
ΔH=ΔU+ΔnRT
⇒ΔH=−885kJmole−1+(−2mole)×8.313×10−3kJmole−1K−1×300K=−889.98kJmole−1
Answer = 890