(∆H −∆U) for the formation of carbon monoxide (CO) from its elements at 298 K is
(R = 8.314 J K^–1 mol^–1)

• –1238.78 J mol^–1

• 1238.78 J mol^–1

• –2477.57 J mol^–1

• 2477.57 J mol^–1

A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of 37.0⁰C. As it does so, it absorbs 208J of heat. The values of q and w for the process will be:(R = 8.314 J/mol K) ( ln 7.5 = 2.01)

• q =+208J, W = - 208 J

• q =-208 J, W =-208 J

• q=-208J, W = +208 J

• q =+208 J, W = +208 J

Consider the reaction: N₂ +3H₂ → 2NH₃ carried out at constant temperature and pressure. If ∆H and ∆U are the enthalpy and internal energy changes for the reaction, which of the following expressions is true? 

• ∆H = 0

• ∆H = ∆U

• ∆H < ∆U

• ∆H >∆U

For a particular reversible reaction at temperature T, ΔH and ΔS were found to be both +ve. If Te is the temperature at equilibrium, the reaction would be spontaneous when 

• T_e>T

• T >T_e

• T_e is 5 times T

• T=T_e

For the complete combustion of ethanol, C₂H₅OH (l) + 3O₂ (g) → 2CO₂ (g) + 3H₂O (l), the amount of heat produced as measured in a bomb calorimeter, is 1364.47 kJ mol-1 at 25^oC. Assuming ideality the enthalpy of combustion, ∆_CH, for the reaction will be (R = 8.314 JK^-1 mol^-1)

• -1366.95 kJ mol^-1

• -1361.95 kJ mol^-1

• -1460.50 kJ mol^-1

• -1350.50 kJ mol^-1

A.

-1366.95 kJ mol^-1

C₂H₅OH (l) + 3O₂ (g) → 2CO₂ (g) + 3H₂O (l),
∆U = - 1364.47 kJ/mol

∆H = ∆U +∆n_gRT
∆n_g = -1
∆H = - 1364.47 +
[Here, value of R in unit of J must be converted into kJ]
 = - 1364.47-2.4776
 = -1366.94 kJ/mol