Q.What is state function? Explain internal energy as a state function.

A state function's value depends only on the current state of the system (defined by variables like T, P, V), not on how the system reached that state — examples include internal energy (U), enthalpy (H), entropy (S), and Gibbs energy (G).

In thermodynamics, properties of a system are classified as either:

• State functions: their change (Delta) depends only on the initial and final states, e.g. internal energy U, enthalpy H, pressure P, volume V, temperature T. If a system goes from state 1 to state 2 by any path — reversible or irreversible, direct or roundabout — Delta(state function) is exactly the same. …

State functions depend only on the initial and final states of the system; work is a path function.

$\Delta G$ (Gibbs energy change), $\Delta U$ (internal energy change) and $\Delta H$ (enthalpy change) are all state functions — they depend only on the initial and final states of the system, not on the path followed.

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Heat and work are path functions individually, but their sum (q + w = dU) equals the change in internal energy, which is a state function.

A state function is a property whose value depends only on the current state of the system (e.g., initial and final states), not on how that state was reached. Examples: internal energy (U), enthalpy (H), entropy (S).

A path function depends on the path/process followed, e.g., heat (q) and work (w) individually — the same overall change of state can be achieved via different combinations of q and w (different paths), so heat and work alone are not state functions.

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A thermodynamic state function's value depends only on the current state of the system (like T, P, V), not on how that state was reached.

Quantities like internal energy (U), enthalpy (H), entropy (S), and Gibbs free energy (G) are state functions — their change (ΔU, ΔH, etc.) between two states is always the same, regardless of the path/process used to go from the initial to the final state. This is different from path functions like heat (q) and work (w), whose values DO depend on the path taken (e.g., work done depends on whether a gas expands reversibly or irreversibly).

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A state function (e.g. internal energy U, enthalpy H) depends only on the current state of the system, never on how that state was reached; quantities like heat q and work w are path functions instead.

A thermodynamic system can move from an initial state to a final state along many different paths (e.g. reversibly or irreversibly, in one step or several). A state function is any property whose value depends only on the initial and final states of the system - it is completely independent of the path followed. Internal energy (U), enthalpy (H), entropy (S), and Gibbs free energy (G) are all state functions: their change (ΔU, ΔH, etc.) is the same no matter which route is taken between the two states.

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