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  2. Acid dissociation constant - Wikipedia

    en.wikipedia.org/wiki/Acid_dissociation_constant

    Free energy is made up of an enthalpy term and an entropy term. [11] = The standard enthalpy change can be determined by calorimetry or by using the van 't Hoff equation, though the calorimetric method is preferable. When both the standard enthalpy change and acid dissociation constant have been determined, the standard entropy change is easily ...

  3. PKA (irradiation) - Wikipedia

    en.wikipedia.org/wiki/PKA_(irradiation)

    Atoms can only be displaced if, upon bombardment, the energy they receive exceeds a threshold energy E d. Likewise, when a moving atom collides with a stationary atom, both atoms will have energy greater than E d after the collision only if the original moving atom had an energy exceeding 2 E d .

  4. Negative energy - Wikipedia

    en.wikipedia.org/wiki/Negative_energy

    The negative-energy particle then crosses the event horizon into the black hole, with the law of conservation of energy requiring that an equal amount of positive energy should escape. In the Penrose process , a body divides in two, with one half gaining negative energy and falling in, while the other half gains an equal amount of positive ...

  5. Field effect (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Field_effect_(chemistry)

    The concentration of negative charge on each chlorine has a through space effect which can be seen in the relative pKa values. [16] When the chlorines are pointed over the carboxylic acid group, the pKa is higher because loss of a proton is less favorable due to the increase in negative charge in the area.

  6. Dissociation constant - Wikipedia

    en.wikipedia.org/wiki/Dissociation_constant

    In chemistry, biochemistry, and pharmacology, a dissociation constant (K D) is a specific type of equilibrium constant that measures the propensity of a larger object to separate (dissociate) reversibly into smaller components, as when a complex falls apart into its component molecules, or when a salt splits up into its component ions.

  7. Zeta potential - Wikipedia

    en.wikipedia.org/wiki/Zeta_potential

    Zeta potential can also be used for the pKa estimation of complex polymers that is otherwise difficult to measure accurately using conventional methods. This can help studying the ionisation behaviour of various synthetic and natural polymers under various conditions and can help in establishing standardised dissolution-pH thresholds for pH ...

  8. Electrophilic aromatic directing groups - Wikipedia

    en.wikipedia.org/wiki/Electrophilic_aromatic...

    This can also explain why phosphorus in phosphanes can't donate electron density to carbon through induction (i.e. +I effect) although it is less electronegative than carbon (2.19 vs 2.55, see electronegativity list) and why hydroiodic acid (pKa = -10) being much more acidic than hydrofluoric acid (pKa = 3).

  9. Energy density - Wikipedia

    en.wikipedia.org/wiki/Energy_density

    The higher the energy density of the fuel, the more energy may be stored or transported for the same amount of volume. The energy of a fuel per unit mass is called its specific energy. The adjacent figure shows the gravimetric and volumetric energy density of some fuels and storage technologies (modified from the Gasoline article).