Which of the following is/are correct?I. When 1 mole of Zn is dissolved in excess HCl in an open beaker at 300 K and 1 atm, the work done is approximately - 2.49 kJ.II. When 1 mole of Zn is dissolved in excess HCl in a closed beaker, the work done is zero.
Correct answer: C. Both (I) and (II) are correct
- A. I only
- B. II only
- C. Both (I) and (II) are correct
- D. Neither (I) nor (II) are correct
Explanation
In the open beaker, H₂ gas is produced, and work is done by the system against the constant atmospheric pressure (W = -ΔngRT). In a closed, rigid beaker, the volume is constant, so no pressure-volume work is done. Both statements are correct.
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Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
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