Chemistry: First principle of thermodynamics

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SUMMARY

The discussion centers on the first principle of thermodynamics, represented by the equation E=q+w. The calculation provided, E=q+w=-17+21=4kJ, indicates an endothermic process, as the positive value of E signifies heat absorption from the surroundings. Participants clarify that option (a) is true because q=-17 kJ indicates heat flows from the system to the surroundings, while option (b) is false. The conclusion reached is that if option (b) is false, then E must also be false, highlighting a logical inconsistency in the problem statement.

PREREQUISITES
  • Understanding of thermodynamic principles, specifically the first law of thermodynamics.
  • Familiarity with the concepts of heat transfer (q) and work (w) in thermodynamic systems.
  • Ability to perform basic thermodynamic calculations involving energy changes.
  • Knowledge of endothermic and exothermic processes in chemistry.
NEXT STEPS
  • Study the implications of the first law of thermodynamics in various chemical reactions.
  • Learn about enthalpy changes and their relationship to heat transfer in chemical processes.
  • Explore the concept of calorimetry and its applications in measuring heat changes.
  • Investigate common misconceptions in thermodynamics, particularly regarding energy flow and work.
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Chemistry students, educators, and anyone studying thermodynamics who seeks to deepen their understanding of energy transfer in chemical reactions.

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Homework Statement


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Homework Equations


First principle of thermodynamics: E=q+w

The Attempt at a Solution


E=q+w=-17+21=4kJ>0
∴Endothermic (absorb heat from surrounding)

(a) false (from surrounding to the system)
(b) false (does work by surrounding)
(c) true
(d) true

the answer states only option b is false... why option a is true?
Thank you very much!
 
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q=-17 kJ means that heat flows from the system to the surroundings. So "a" is not false.

And why are you using E=q+w=-17+21=4kJ>0 to say that
∴Endothermic (absorb heat from surrounding)?
 
I see. thanks.
 
It is impossible for only option B to be false. If B is false E is also false.
 
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Likes   Reactions: DrClaude
mjc123 said:
It is impossible for only option B to be false. If B is false E is also false.
Good catch.
 

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