JEE Advance - Chemistry (2012 - Paper 2 Offline - No. 10)
Using the data provided, calculate the multiple bond energy (kJ mol$$-$$1) of a C=C bond in C2H2. That energy is (take the bond energy of C-H bond as 350 kJ mol$$-$$1).
$$\matrix{ \hfill {2C(s) + {H_2}(g) \to {C_2}{H_2}} & \hfill {\Delta H = 225\,kJ\,mo{l^{ - 1}}} \cr \hfill {2C(s) \to 2C(g)} & \hfill {\Delta H = 1410\,kJ\,mo{l^{ - 1}}} \cr \hfill {{H_2}(g) \to 2H(g)} & \hfill {\Delta H = 330\,kJ\,mo{l^{ - 1}}} \cr } $$
1165 kJ mol$$-$$1
837 kJ mol$$-$$1
865 kJ mol$$-$$1
815 kJ mol$$-$$1
Explanation
We know that
Binding energy = Total energy of reactants $$-$$ Total energy of products
So, we have
225 = 2(C $$-$$ C) + 1(H $$-$$ H) $$-$$ 2(C $$-$$ H) + 1(C $$\equiv$$ C)
225 = 1410 + 330 $$-$$ 2 $$\times$$ 350 + (C $$\equiv$$ C)
Solving, we get the value of C $$\equiv$$ C as 815 kJ mol$$-$$1.
Comments (0)
