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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 .
In organic carboxylic acids, an electronegative substituent can pull electron density out of an acidic bond through the inductive effect, resulting in a smaller value. The effect decreases, the further the electronegative element is from the carboxylate group, as illustrated by the following series of halogenated butanoic acids .
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 ...
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 ...
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 ...
Trimethylsilylmethylamine (Me 3 SiCH 2 NH 2) is a stronger base (conjugate pK a 10.96) than neopentylamine (conjugate pK a 10.21); trimethylsilylacetic acid (pKa 5.22) is a poorer acid than trimethylacetic acid (pKa 5.00). [1] In 1994, Yong and coworkers compared the free-energy effects of α- and β-Si(CH 3) 3 moieties on C–H homo- and ...
Generally, the pzc in electrochemistry is the value of the negative decimal logarithm of the activity of the potential-determining ion in the bulk fluid. [2] The pzc is of fundamental importance in surface science. For example, in the field of environmental science, it determines how easily a substrate is able to adsorb potentially harmful ions.
The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.