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NEET CHEMISTRYThermodynamicsEasy

Question

What is the correct relationship between changes in enthalpy and internal energy within the following options?

A

\Delta H + \Delta U = \Delta nR

B

\Delta H = \Delta U - \Delta ngRT

C

\Delta H = \Delta U + \Delta ngRT

D

\Delta H - \Delta U = -\Delta ngRT

Step-by-Step Solution

The change in enthalpy (\Delta H) for a system is related to the change in internal energy (\Delta U) by the equation \Delta H = \Delta U + p\Delta V. For reactions involving gases, assuming ideal gas behaviour (pV = nRT), the change in volume at constant temperature and pressure is due to the change in the number of moles of gaseous substances. Therefore, p\Delta V can be replaced by \Delta ngRT, where \Delta ng is the difference between the number of moles of gaseous products and gaseous reactants. Substituting this gives the fundamental thermodynamic relationship: \Delta H = \Delta U + \Delta ngRT .

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Thermodynamics. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

CHEMISTRYThermodynamicscorrectrelationshipbetweenchangesenthalpy

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