Consider the hydrogenation of a carbon nitrogen double bond C=N (i.e. adding a h
ID: 1064246 • Letter: C
Question
Consider the hydrogenation of a carbon nitrogen double bond C=N (i.e. adding a hydrogen on the carbon and nitrogen atoms thus reducing the double bond into a single bond: H-C-N-H. Using the data from the following table, calculate the Hreaction of the following reaction:
CH3-CH=N-H(g) + H2(g) --> CH3-CH2-NH2(g)
Bond
Bond enthalpy (kJ/mol)
C=N
615
C-N
276
H-H
436
N-H
393
C-H
414
The Hreaction is
Question options:
89 kJ/mol
-89 kJ/mol
-32 kJ/mol
32 kJ/mol
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Bond
Bond enthalpy (kJ/mol)
C=N
615
C-N
276
H-H
436
N-H
393
C-H
414
Explanation / Answer
The reaction involves
breakage of one C=N bond
breakage of one H-H bond
formation of one C-H bond
formation of one N-H bond
formation of one C-N bond
The enthalpy change for the reaction will be given by
H = ( HC=N + HH-H) - ( HC-H + H N-H+H C-N)
= (615 + 436) - (414+393+276)
= -32 kJ/mol