Question #b4cdf

1 Answer
Aug 20, 2016

Given

  • #V->"Volume of "CH_4(g)=0.1L#
  • #P->"Pressure of "CH_4(g)=744mm=744/760atm#
  • #T->"Temperature of "CH_4(g)=25^@C=298K#
  • #R->"Universal gas constant"=0.082LatmK^-1mol^-1#

Let

  • #n->"Number of moles"CH_4(g) =?#

By equation of state of ideal gas

#n=(PV)/(RT)=(744xx0.1)/(760xx0.082xx293)=0.004"mol"#

Now From combustion data the heat of combustion of methane is #890kJmol^-1#

#CH_4(g)+2O_2(g)->CO_2(g)+2H_2O(l),DeltaH^@=-890kJ"mol"^-1#

So amount of heat evolved by combustion of 0.004mol#CH_4(g)# is #=0.004xx890kJ=3560J#

Now we know that melting of 1g ice to 1g water requires 336J heat without raising its temperature

So 9.53g of ice requires #9.53xx336J=3202.8J# heat to melt into water of #0^@C#

As the previous calculation of complete combustion #CH_4(g)# provides 3560J heat and which is greater than the value obtained from heat of melting of ice (3202.8J), It can be said that the combustion of #CH_4(g)# is incomplete in this case.