Question

The standard heat of formation, ΔH∘f, is defined as the enthalpy change for the formation of one mole of substance from its constituent elements in their standard states. Thus, elements in their standard states have ΔH∘f=0. Heat of formation values can be used to calculate the enthalpy change of any reaction.

Consider, for example, the reaction

2NO(g)+O2(g)⇌2NO2(g)

with heat of formation values given by the following table:

Substance	ΔH∘f (kJ/mol)
NO(g)	90.2
O2(g)	0
NO2(g)	33.2

Then the heat of formation for the overall reaction is

ΔH∘rxn===ΔH∘f(products)2(33.2)−114 kJ/mol−−ΔH∘f(reactants)[2(90.2)+0]

For which of the following reactions is ΔH∘rxn equal to ΔH∘f of the product(s)?

You do not need to look up any values to answer this question.

Check all that apply.

View Available Hint(s)

Check all that apply.

Li(s)+12Cl2(l)→LiCl(s)

Li(s)+12Cl2(g)→LiCl(s)

SO3(g)→12O2(g)+SO2(g)

SO(g)+12O2(g)→SO2(g)

2Li(s)+Cl2(g)→2LiCl(s)

S(s)+O2(g)→SO2(g)

The combustion of propane, C3H8, occurs via the reaction

C3H8(g)+5O2(g)→3CO2(g)+4H2O(g)

with heat of formation values given by the following table:

Substance	ΔH∘f (kJ/mol)
C3H8 (g)	-104.7
CO2(g)	−393.5
H2O(g)	−241.8

Calculate the enthalpy for the combustion of propane.

Answer 1

Hope this helped you!

Thank You So Much! Please Rate this answer as you wish.("Thumbs Up")