Which of the following is/are correct?
Correct answer: C. Both (a) and (b) are correct.
- A. When 1 mole of Zn is dissolved in excess HCl, the work done is approximately equal to -2.46 kJ in an open beaker at 300 K and 1 atm.
- B. When 1 mole of Zn is dissolved in excess HCl, the work done is zero in a closed beaker.
- C. Both (a) and (b) are correct.
- D. Neither (a) nor (b) are correct.
Explanation
The correct answer is Option C: Both (a) and (b) are correct. In an open beaker, when zinc reacts with hydrochloric acid, work is done as the system expands against the atmospheric pressure, resulting in a negative value for work done, approximately -2.46 kJ under standard conditions (300 K, 1 atm). Conversely, in a closed beaker, there is no change in volume that can perform work on the surroundings, hence the work done is zero. Therefore, both options A and B accurately describe the scenarios provided.
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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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