化学热量计算已知下列各反应的反应热:Ca(s) + C(s,石墨) + 3/2 O2(g) = CaCO3 (s) △H = - 1206.8 kJ/molCa(s) + 1/2 O2(g) = CaO(s) △H = - 635.1 kJ/molC(s,石墨) + O2(g) = CO2 (g) △H = - 393.5 kJ/mol则CaCO3(s) = CaO(s) + CO2(g)
化学热量计算已知下列各反应的反应热:Ca(s) + C(s,石墨) + 3/2 O2(g) = CaCO3 (s) △H = - 1206.8 kJ/molCa(s) + 1/2 O2(g) = CaO(s) △H = - 635.1 kJ/molC(s,石墨) + O2(g) = CO2 (g) △H = - 393.5 kJ/mol则CaCO3(s) = CaO(s) + CO2(g)
化学热量计算
已知下列各反应的反应热:
Ca(s) + C(s,石墨) + 3/2 O2(g) = CaCO3 (s) △H = - 1206.8 kJ/mol
Ca(s) + 1/2 O2(g) = CaO(s) △H = - 635.1 kJ/mol
C(s,石墨) + O2(g) = CO2 (g) △H = - 393.5 kJ/mol
则CaCO3(s) = CaO(s) + CO2(g) 的反应热△H为
A.+178.2 kJ/mol B.-178.2 kJ/mol C.+965.3 kJ/mol D. -965.3 kJ/mol
怎么考虑?
化学热量计算已知下列各反应的反应热:Ca(s) + C(s,石墨) + 3/2 O2(g) = CaCO3 (s) △H = - 1206.8 kJ/molCa(s) + 1/2 O2(g) = CaO(s) △H = - 635.1 kJ/molC(s,石墨) + O2(g) = CO2 (g) △H = - 393.5 kJ/mol则CaCO3(s) = CaO(s) + CO2(g)
选A
CaCO3 (s) = Ca(s) + C(s,石墨) + 3/2 O2(g) △H1 = 1206.8 kJ/mol
Ca(s) + 1/2 O2(g) = CaO(s) △H2 = - 635.1 kJ/mol
C(s,石墨) + O2(g) = CO2 (g) △H3 = - 393.5 kJ/mol
以上三个反应相加,就可以得到CaCO3(s) = CaO(s) + CO2(g)
因此,反应热也是相加的关系△H =△H1+△H2+△H3=178.2 kJ/mol
A
反应2+反应3-反应1