In some circumstances, dehydrogenation is observed. Dehydrogenation involves the loss of two hydrogen atoms (the reverse of hydrogenation). Analyze each of the following dehydrogenation reactions and then use the information in Figure 18.1 to predict whether each transformation will be downhill in energy (negative value for ΔH) or uphill in energy (positive value for ΔH).

Figure 18.1

a.

b.

c.

Transcribed Image Text:

Expected ЗНа 152 kJ/mol + 2H2 + ЗН2 Actual Energy | + H2 Expected -360 kJ/mol Observed -232 kJ/mol -208 kJ/mol -120 kJ/mol H2