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已知298K时下述反应:①C(s)+1/2O2(g)=CO(g)△H1=-110.5kJ•mol-1②CO(g)+1/2O2(g)=CO2(g)△H2=-283.0kJ•mol-1③C(s)+CO2(g)=2CO(g)△H3,则△H3等于()A.172.5kJ

题目详情
已知298K时下述反应:
①C(s)+1/2O 2 (g)=CO(g)△H 1 =-110.5kJ•mol -1
②CO(g)+1/2O 2 (g)=CO 2 (g)△H 2 =-283.0kJ•mol -1
③C(s)+CO 2 (g)=2CO(g)△H 3
则△H 3 等于(  )
A.172.5kJ•mol -1 B.-172.5kJ•mol -1
C.393.5kJ•mol -1 D.-393.5kJ•mol -1
▼优质解答
答案和解析
①C(s)+1/2O 2 (g)=CO(g)△H 1 =-110.5kJ•mol -1
②CO(g)+1/2O 2 (g)=CO 2 (g)△H 2 =-283.0kJ•mol -1
依据盖斯定律①-②得到:C(s)+CO 2 (g)=2CO(g)△H 3 =172.5kJ•mol -1
故选A.