Cho các phương trình nhiệt hóa học sau: (a) C ( s ) + O 2 (   g ) → C O 2 (   g ) Δ r H 2 9 8 ° = − 3 9 3 , 5   k J / (b)

Cho các phương trình nhiệt hóa học sau:

(a) $\text{C}(\text{s})+\text{O}{}_2( \text{g})\to \text{C}\text{O}{}_2( \text{g})\Delta {}_{\text{r}}\text{H}{}_{298}^{°}=-393,5 \text{k}\text{J}/$

(b) $2\text{H}\text{g}\text{O}(\text{s})\to 2\text{H}\text{g}(\text{g})+\text{O}{}_2( \text{g})\Delta {}_{\text{r}}\text{H}{}_{298}^{°}=+90 \text{k}\text{J}$

(c) $2\text{H}{}_2( \text{g})+\text{O}{}_2( \text{g})\to 2\text{H}{}_2\text{O}(\text{g})\Delta {}_{\text{r}}\text{H}{}_{298}^{°}=-571,5 \text{k}\text{J}$

(d) $\text{C}\text{a}\text{C}\text{O}{}_3( \text{s})\to \text{C}\text{a}\text{O}(\text{s})+\text{C}\text{O}{}_2( \text{g})\Delta {}_{\text{r}}\text{H}{}_{298}^{°}=+176,0 \text{k}\text{J}$

(e) $4\text{A}\text{l}(\text{s})+3\text{O}{}_2( \text{g})\to 2\text{A}\text{l}{}_2\text{O}{}_3( \text{s})\Delta {}_{\text{r}}\text{H}{}_{298}^{°}=-1657.7 \text{k}\text{J}$

Số phàn ứng toà nhiệt là