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  2. Van 't Hoff equation - Wikipedia

    en.wikipedia.org/wiki/Van_'t_Hoff_equation

    Assume two products B and C form in a reaction: a A + d D → b B, a A + d D → c C. In this case, K eq can be defined as ratio of B to C rather than the equilibrium constant. When ⁠ B / C ⁠ > 1, B is the favored product, and the data on the Van 't Hoff plot will be in the positive region.

  3. Delta potential - Wikipedia

    en.wikipedia.org/wiki/Delta_potential

    The delta potential is the potential = (), where δ(x) is the Dirac delta function. It is called a delta potential well if λ is negative, and a delta potential barrier if λ is positive. The delta has been defined to occur at the origin for simplicity; a shift in the delta function's argument does not change any of the following results.

  4. Hessian matrix - Wikipedia

    en.wikipedia.org/wiki/Hessian_matrix

    The above rules stating that extrema are characterized (among critical points with a non-singular Hessian) by a positive-definite or negative-definite Hessian cannot apply here since a bordered Hessian can neither be negative-definite nor positive-definite, as = if is any vector whose sole non-zero entry is its first.

  5. Arrhenius equation - Wikipedia

    en.wikipedia.org/wiki/Arrhenius_equation

    This has the same form as an equation for a straight line: = +, where x is the reciprocal of T. So, when a reaction has a rate constant obeying the Arrhenius equation, a plot of ln k versus T −1 gives a straight line, whose slope and intercept can be used to determine E a and A respectively. This procedure is common in experimental chemical ...

  6. Thermodynamic free energy - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_free_energy

    Historically, the term 'free energy' has been used for either quantity. In physics, free energy most often refers to the Helmholtz free energy, denoted by A (or F), while in chemistry, free energy most often refers to the Gibbs free energy. The values of the two free energies are usually quite similar and the intended free energy function is ...

  7. Helmholtz free energy - Wikipedia

    en.wikipedia.org/wiki/Helmholtz_free_energy

    This result seems to contradict the equation dF = −S dT − P dV, as keeping T and V constant seems to imply dF = 0, and hence F = constant. In reality there is no contradiction: In a simple one-component system, to which the validity of the equation d F = − S d T − P d V is restricted, no process can occur at constant T and V , since ...

  8. Dirac delta function - Wikipedia

    en.wikipedia.org/wiki/Dirac_delta_function

    The graph of the Dirac delta is usually thought of as following the whole x-axis and the positive y-axis. [5]: 174 The Dirac delta is used to model a tall narrow spike function (an impulse), and other similar abstractions such as a point charge, point mass or electron point.

  9. Gibbs free energy - Wikipedia

    en.wikipedia.org/wiki/Gibbs_free_energy

    In thermodynamics, the Gibbs free energy (or Gibbs energy as the recommended name; symbol ) is a thermodynamic potential that can be used to calculate the maximum amount of work, other than pressure–volume work, that may be performed by a thermodynamically closed system at constant temperature and pressure.