Question

1. If q 60 kJ and w = 96 kJ for a certain process, that process (3) a. requires a catalyst. b. is endothermic. c. occurs slowly. d. is exothermic. e. cannot occur. 2. What is the change in internal energy of the system (AU) if 71 kJ of heat energy is absorbed by the system and 12 kJ of work is done on the system for a certain process? (4) a. 83 kJ b. 59 kJ c. 71 kJ d. -83 kJ e. -59 kJ 3. Which of the following statements about enthalpy is false? a. Enthalpy is a state function. b. At constant pressure, the enthalpy change is equal to the heat absorbed or released. c. Enthalpy is an extensive property d. The change in enthalpy of a process cannot be negative. e. The SI unit of enthalpy is J. (3)

Answer 1

According to first law of thermodynamics

dU = q+W

where dU = internal energy =

q= heat gained = 60 kj [positive for endothermic]

W = work done

since q is positive , the reaction needs heat, hence endothermic

option B) endothermic
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2)
dU = q+W

where dU = internal energy = ?

q= heat gained =71 kj [positive for endothermic]

W = work done = 12 KJ
dU = 71+ 12 = 83 KJ

option A
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3) for exothermic process, enthalpy is negative and for endothermic process
enthalpy is positive
hence false statement is
option D)
the change in enthalpy of a process cannot be negative
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thanks