4.5 Enthalpy changes of combustion

Question 1

What is the enthalpy change of combustion
∆cH

Answer 1

The enthalpy change when 1 mol of substance is completely burnt in oxygen under standard conditions

Question 1

You can use enthalpy changes of combustion to find the overall enthalpy change

Eg in
C2H2(g) + 2H2(g) —> C2H6(g)

Answer 1

Write out the products underneath the equation
2CO2 + 3H2O

and above it, add 3.5O2 to the reaction, as it is burning in oxygen

And sub in values