Post a New Question


posted by .

Combustion reactions involve reacting a substance with oxygen. When compounds containing carbon and hydrogen are combusted, carbon dioxide and water are the products. Using the enthalpies of combustion for C4H4 (-2341 kJ/mol), C4H8 (-2755 kJ/mol), and H2 (-286 kJ/mol), calculate H for the reaction.
C4H4(g) + 2 H2(g) C4H8(g)

very confused

  • chem -

    What they want you to do here is to use Hess' Law. Write the reactions as combustion reactions.
    C4H4 + 5O2 ==> 4CO2 + 2H2O -2341 kJ/mol
    2H2 + O2 =>2H2O -286 kJ/MOL= -572 rxn
    C4H8 + 6O2 ==> 4CO2 + 4H2O -2755 kJ/mol
    Add the sum of equation 1 and equation 2 to the reverse of equation 3 to give you the reaction you have written (You shouldn't omit the arrow--it makes us guess where the arrow should be). Delta H for the reaction you have written will then be the sum of delta H for equation 1 and equation 2 + delta H for equation 3 (with the sign changed since you changed the direction of the reaction). I've almost worked the entire problem for you.
    Post your work if you get stuck.

Answer This Question

First Name:
School Subject:

Related Questions

More Related Questions

Post a New Question