2 B(s)+32O2(g)→B2O3(s)ΔH=−1273 kg mol−1
H2(g)+12O2(s)→H2(1)ΔH=286 kg mol−1
−H2O(1)→H2O(g)Δ=44 kg mol−1
−20(s)+3H2(g)→B2H6(g).ΔH=36 kg mol−1
B2H6(g)→2B(g)+3H(g)ΔH1=−36
3×(H2(g)+12O2(g)→H2O(l)) ΔH2=−286×3
3×(H2O(l)→H2O(g)) ΔH3=44×3
2B(s)+32O2(g)→B2O3(s) ΔH4=−1273
B2H6(g)+3O2→B2O3+3H2O
ΔH=−36−286×3+44×3−1273
ΔH=−36−858+132−1273=−2035 kg mol−1