Question

Question #b4cdf

Answer 1

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.