Some mean bond enthalpies are given in the table below.
| Bond | C−C\text{C}-\text{C}C−C | C=C\text{C}=\text{C}C=C | C−H\text{C}-\text{H}C−H | Cl−Cl\text{Cl}-\text{Cl}Cl−Cl | C−Cl\text{C}-\text{Cl}C−Cl |
|---|---|---|---|---|---|
| Mean bond enthalpy / kJ mol−1\text{kJ~mol}^{-1}kJ mol−1 | 347 | 614 | 413 | 242 | 339 |
What is the enthalpy change, in kJ mol−1\text{kJ~mol}^{-1}kJ mol−1, for the gas-phase addition of chlorine to ethene?
C2H4(g)+Cl2(g)→CH2ClCH2Cl(g) \text{C}_2\text{H}_4\text{(g)} + \text{Cl}_2\text{(g)} \rightarrow \text{CH}_2\text{Cl}\text{CH}_2\text{Cl}\text{(g)} C2H4(g)+Cl2(g)→CH2ClCH2Cl(g)−411-411−411
−169-169−169
+169+169+169
+411+411+411