Question

Consider the reaction for the formation of aluminum oxide from aluminum and oxygen.

4Al(s)+3O2(g)⟶2Al2O3(s) ΔH1

1. Express the enthalpy of the following reaction, ΔH2, in terms of ΔH1.

2Al2O3(s)⟶4Al(s)+3O2(g) ΔH2

ΔH2=

2. Express the enthalpy of the following reaction, ΔH3, in terms of ΔH1.

12Al(s)+9O2(g)⟶6Al2O3(s) ΔH3 12Al(s)+9O2(g)⟶6Al2O3(s) ΔH3

ΔH3=

3. Express the enthalpy of the following reaction, ΔH4, in terms of ΔH1.

2Al(s)+32O2(g)⟶Al2O3(s) ΔH4  2Al(s)+32O2(g)⟶Al2O3(s) ΔH4

ΔH4=

Answer 1

1)

This reaction is -1*given reaction

So,

ΔH2 = -1* ΔH1

= -ΔH1

Answer -ΔH1

2)

This reaction is 3*given reaction

So,

ΔH3 rxn = 3*given ΔHo rxn

= 3ΔH1

Answer: 3ΔH1

3)

This reaction is 0.5*given reaction

So,

ΔH4 rxn = 0.5*given ΔHo rxn

= 0.5ΔH1

Answer: 0.5ΔH1