Question

What is the difference between delta h and delta u for the combustion of toluene at 300 kelvin?

Answer 1

Answer:

-2RT

Explanation:

C7H8+ 9O2 gives 7CO2+4H2O( enthalpy of combustion of toluene)

here, O2 and CO2 are gases

So,

number moles = no. of moles product - no. of moles of reactant

ie., no. of moles = 7-9= -2

we have equation,

delta H= deltaU + nRT

so, delta H - Delta U = nRT

here n = -2

So Delta H - Delta U = -2RT

Answer 2

Given: Combustion of toluene at 300 K is carried out

To find: Difference between delta H and delta U

Explanation: The reaction for combustion of toluene is:

C7H8(g) + 9 O2(g) -----> 7 CO2(g) + 4 H2O(g)

We need to calculate n from this equation where n is difference in number of moles of gaseous products in the product and reactant side.

n= Moles of gaseous products- Moles of gaseous reactants

=> n = (7+4)- (9+1)

= 11-10

= 1

Temperature (T)= 300 K

Now, formula relating delta H, delta U and n is:

delta H- delta U = nRT where R is gas constant

= 1* 8.314* 300

= 2494.2 J

The difference between delta H and delta U at 300 K for combustion of toluene is 2494.2 J.