Foundations & State Functions Flashcards
(12 cards)
What is the central objective of chemical thermodynamics?
To describe and predict the energetic and entropic changes that accompany chemical and physical processes, thereby determining spontaneity and equilibrium.
Why is chemical thermodynamics considered a macroscopic discipline despite its molecular basis?
Because it relies on bulk-state variables (e.g., pressure, temperature, enthalpy, entropy) that average over immense numbers of molecules rather than tracking individual particles.
Name three state functions central to chemical thermodynamics.
Internal energy (E), enthalpy (H), and entropy (S).
Why are state functions path-independent?
Their values are fully determined by the equilibrium state of the system and not by the specific sequence of steps used to reach that state.
Provide the thermodynamic definition of energy.
Energy is the capacity to perform work or to transfer heat.
State the Law of Conservation of Energy.
Energy may be converted from one form to another, but it can neither be created nor destroyed.
Differentiate between heat (q) and work (w).
Heat is energy transfer driven by a temperature gradient; work is energy transfer that results when an object exerts a force through a distance.
Explain why energy is described as a scalar quantity.
It possesses magnitude only; its effects do not depend on direction in space.
Define potential energy in a chemical context.
Potential energy is stored energy arising from position, composition, or electrostatic interactions within a system’s particles.
Provide the mathematical expression for translational kinetic energy of a body and identify its variables.
KE = 1/2 mv², where m is mass and v is velocity.
Why does a water reservoir behind a dam exemplify potential energy?
Its elevation relative to the turbines confers gravitational potential that can be converted into mechanical work as water descends.
At the molecular level, how is kinetic energy manifested?
Through translational, rotational, and vibrational motion of molecules.
