Predict the sign of ΔS° for the following reaction.
At room temperature the reaction between propene (CH2=CH−CH3) and hydrogen gas (H2) to form propane (CH3−CH2−CH3) goes to completion when a platinum catalyst is present in the reaction mixture.
Determine the signs of ΔH° and ΔS° for this addition reaction based on the information given above.
Explain these signs in terms of freedom of motion and bonding.
CH2=CH−CH3 + H2 (Pt catalyst) → CH3−CH2−CH3
The dehydrogenation of ethane (CH3−CH3) to ethene (CH2=CH2) has ΔH° = +136 kJ/mol (+32.5 kcal/mol) and ΔS° = +120 J/kelvin-mol (+28.7 cal/kelvin-mol). Calculate the value of ΔG° for the reaction at room temperature. Is the reaction favored or disfavored?