Energy adding/releasing/absorbing

Why is energy usually released when an electron is added to a neutral atom but absorbed when an electron is removed from a neutral atom ... 

In this reaction, water from the solid (s) gypsum is released in gas (g) form. It is an endothermic reaction (energy is absorbed). The reverse reaction, in which liquid (1) water is added to the plaster of Paris, is exothermic (energy is released) ... 

The amount of energy absorbed in the process in which an electron is added to a neutral isolated gaseous atom to form a gaseous ion with a 1- charge has a negative value if energy is released. 

In most cases, energy is released when the first electron is added because it is attracted to the atom s nuclear charge. Thus, EA, is usually negative (just as A// for an exothermic reaction is negative). The second electron affinity (EA2), on the other hand, is always positive because energy must be absorbed... 

For this reaction, the amount of energy released exceeds the amount of energy absorbed. The net energy of the reaction is found by adding the two quantities ... 

Because the energy released on adding an electron to H+ is equal to the energy absorbed on removing an electron from a hydrogen atom, we can also say that 1312 kjjmol is required to remove the electron from a hydrogen atom. We ll see in the... 

The method is based on the fact that when a sample is irradiated in a nuclear reactor for a specific length of time, atoms of some elements absorb neutrons. Nuclei that acquire an excess electron have a large excess of energy that is often released in the form of gamma rays. Nuclei with added neutrons are called radionuclides. 

One consequence of water s high heat of vaporization (the energy required to vaporize one mole of a liquid at a pressure of one atmosphere) and high heat capacity (the energy that must be added or removed to change the temperature by one degree Celsius) is that water acts as an effective modulator of climatic temperature. Water can absorb and store solar heat and release it slowly. Consider,... 

Chlorophyll a fluorescence induaion is a widespread method to evaluate the photosynthetic activity. This method is noninvasive, highly sensitive, fast, and easily measured. When chlorophyll molecules in photosystem II absorb light, that light may be assimilated into the hght reactions of photosynthesis or may be released as fluorescence or heat energy. In vivo fluorescence increases when photosynthesis declines or is inhibited. Numerous environmental f ors can affect the rate of electron transport between photosystem II and photosystem I due to interference with electron carriers between the two photosystems. For example, when the diuton is added in the measured sample, electron transport from photosystem II to photosystem I is blocked resulting in maximum fluorescence. This method was often employed to detect the photosynthetic activity of immobilized photosynthetic material. ... 

Propellant Processing Configuration. The purpose of this test was to observe the behavior of propellant and aluminum as found in a noncontaminated M55 rocket motor and to demonstrate the ability of added water to absorb energy released from the propellant as that energy is conveyed to the offgas treatment system. Actual rockets were not used in the test. Instead, a propellant having characteristics similar to those of an M55 rocket and aluminum strips of the same composition as the fins in an M55 rocket were used. 

In the CM-chitosan solutions that contained 0.02mol/L H2O2 (condition c) or 2.5 x 10" mol/L N2O (condition b), were 280% and 150% of that in condition a (Nj-saturated). In condition d, because 0.76 mol/L isopropanol was added into the CM-chitosan solution, G decreased to 5% of that in condition a. Similar to the degradation mechanism of chitosan in aqueous solution, the radiation energy of y-ray is absorbed mainly by water in dilute CM-chitosan aqueous solutions, and the direct effect of radiation on CM-chitosan can be neglected. The radiation chemical yield of reactive species released in the radiolysis of water are constant in the wide range of pH. In condition a, CM-chitosan aqueous solution was radiated with saturated N2. The active species that resulted in... 

The use of various absorbance profiles for different analyte concentrations has been applied, with activation energy independent of the amount of analyte. In this case, the main problem was due to the fact that the order of release and the activation energy were deduced from different and in many cases very short temperature ranges. Beside the ad-sorption/desorption processes, a second modeling approach based on condensation/evaporization processes have been proposed where some features of the atomization process are also interpreted - double values of the activation energy, values of E empirical relationship between Ea and Tapp (appearance) as well as the theoretical activation energies and preexponential factors. 

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