Thermodynamics spontaneous processes

The value of AG is only ever negative, as required by a thermodynamically spontaneous process, if the initial pressure / (initial) is greater than the final pressure finai), i.e. the fraction is less than one. In other words, Equation (5.9) shows why AG is negative only if the pressure of the CO2 in the space above the liquid has a pressure that is greater than... 

The carboxylation of acetone with HCO to form acetoacetate (the reverse of Eq. 13-44) is not a thermodynamically spontaneous process (AG0 ... 

Adsorption is a surface phenomenon. When a multi-component fluid mixture is contacted with a solid adsorbent, certain components of the mixture (adsorbates) are preferentially concentrated (selectively adsorbed) near the solid surface creating an adsorbed phase. This is because of the differences in the fluid-solid molecular forces of attraction between the components of the mixture. The difference in the compositions of the adsorbed and the bulk fluid phases forms the basis of separation by adsorption. It is a thermodynamically spontaneous process, which is exothermic in nature. The reverse process by which the adsorbed molecules are removed from the solid surface to the bulk fluid phase is called desorption. Energy must be supplied to carry out the endothermic desorption process. Both adsorption and desorption form two vital and integral steps of a practical adsorptive separation process where the adsorbent is repeatedly used. This concept of regenerative use of the adsorbent is key to the commercial and economic viability of this technology. 

This step has a negative potential and is not a thermodynamically spontaneous process. This means that a basic solution oxidation of VO to V2O is a thermodynamically favourable process, and V2O3 is more stable than VO in presence of oxygen. 

After the correct aminoacyl-lRNA has been placed in the A site, the transfer of the polypeptide chain from the tRNA in the P site is a thermodynamically spontaneous process, driven by the formation of the stronger peptide bond in place of the ester linkage. However, protein synthesis cannot con-linue without the translocation of the mRNA and the tRNAs within the ribosome. The mRNA must move by a distance of three nucleotides so that the next codon is positioned in the A site for interaction with the incoming aminoacyl-tRNA. At the same time, the deacylated tRNA moves out of the P site into the E site on the 30S subunit and the peptidyl-tRNA moves out of the A site into the P site on the 30S subunit. The movement of the peptidyl-tRNA into the P site shifts the mRNA by one codon, exposing the next codon to be translated in the A site. 

The second law of thermodynamics (spontaneous process). The second law of thermodynamics (equitihrium process). Standard entropy change of a reaction. 

Give a detailed example of each of the following, with an explanation (a) a thermodynamically spontaneous process (b) a process that would violate the first law of thermodynamics (c) a process that would violate the second law of thermodynamics (d) an irreversible process (e) an equilibrium process. 

But suppose that we wanted to convert the polymer back into monomer. In that case, the necessary reaction is the reverse of the polymerization, and it is not a thermodynamically spontaneous process at ordinary temperatures. We could still drive the reaction backward to produce methyl methacrylate monomer. But we would need to maintain a high temperature, providing enough energy to allow the molecules to go against nature s preferred direction. So what is the role of energy in the directionality of nature ... 

Give a detailed example of each of the following, with an explanation (a) a thermodynamically spontaneous process,... 

If there are no reactions, the conservation of the total quantity of each species dictates that the time dependence of is given by minus the divergence of the flux ps vs), where (vs) is the drift velocity of the species s. The latter is proportional to the average force acting locally on species s, which is the thermodynamic force, equal to minus the gradient of the thermodynamic potential. In the local coupling approximation the mobility appears as a proportionality constant M. For spontaneous processes near equilibrium it is important that a noise term T] t) is retained [146]. Thus dynamic equations of the form... 

The oxidation of hydrogen to water (Hj -t- i Oj -> HjO) is thermodynamically spontaneous and the energy released as a result of the chemical reaction appears as heat energy, but the decomposition of water into its elements is a non-spontaneous process and can be achieved only by supplying energy from an external source, e.g. a source of e.m.f. that decomposes the water electrolytically. Furthermore, although the heat produced by the spontaneous reaction could be converted into electrical energy, the electrical... 

The relationship between entropy change and spontaneity can be expressed through a basic principle of nature known as the second law of thermodynamics. One way to state this law is to say that in a spontaneous process, there is a net increase in entropy, taking into account both system and surroundings. That is,... 

Second law of thermodynamics A basic law of nature, one form of which states that all spontaneous processes occur with an increase in entropy, 457 Second order reaction A reaction whose rate depends on the second power of reactant concentration, 289,317q gas-phase, 300t... 

Thermodynamic, second law The entropy of the universe increases in a spontaneous process and remains unchanged in a reversible process. It can never decrease. 

Since q >0, and l/T > /T2 with T2 >7), we conclude that AS for this allowed, spontaneous process is greater than zero. Having obtained this result for the specific case, we can extend it to the general case, because our earlier conclusion that there is an allowed direction to spontaneous adiabatic processes applies to all thermodynamic systems. 

Entropy is a measure of disorder according to the second law of thermodynamics, the entropy of an isolated system increases in any spontaneous process. Entropy is a state function. 

In mammalian cells, the two most common forms of covalent modification are partial proteolysis and ph osphorylation. Because cells lack the ability to reunite the two portions of a protein produced by hydrolysis of a peptide bond, proteolysis constitutes an irreversible modification. By contrast, phosphorylation is a reversible modification process. The phosphorylation of proteins on seryl, threonyl, or tyrosyl residues, catalyzed by protein kinases, is thermodynamically spontaneous. Equally spontaneous is the hydrolytic removal of these phosphoryl groups by enzymes called protein phosphatases. 

Every process has a preferred direction, which is referred to in thermodynamics as the spontaneous direction. Left to itself, a process follows Its spontaneous direction. For example, the spontaneous direction for water movement Is downhill, from higher altitude to lower altitude. A spontaneous process can be reversed only by the action of some outside force. Water runs uphill only If an external agent, such as a pump, forces it to do so. 

Notice that the word spontaneous has a different meaning in thermodynamics than it does in everyday speech. Ordinarily, spontaneous refers to an event that takes place without any effort or premeditation. For example, a crowd cheers spontaneously for an outstanding performance. In thermodynamics, spontaneous refers only to the natural direction of a process, without regard to whether it occurs rapidly and easily. Chemical kinetics, which we introduce in Chapter 15, describes the factors that determine the speeds of chemical reactions. Thermodynamic spontaneity refers to the direction that a process will take if left alone and given enough time. 

We see that the total change in entropy is a positive quantity for both these spontaneous processes, even though one process is exothermic and the other is endothermic. When this type of calculation is carried out for other processes, the same result is always obtained. For any spontaneous process, the total change of entropy is a positive quantity. Thus, this new state function of entropy provides a thermod3mamic criterion for spontaneity, which is summarized in the second law of thermodynamics ... 

C14-0117. The notion of thermodynamic coupling of a nonspontaneous process with a spontaneous process is not restricted to chemical reactions. Identify the spontaneous and nonspontaneous portions of the following coupled processes (a) Water behind a dam passes through a turbine and generates electricity, (b) A gasoline engine pumps water from a valley to the top of a hill. 

In thermodynamics, entropy enjoys the status as an infallible criterion of spontaneity. The concept of entropy could be used to determine whether or not a given process would take place spontaneously. It has been found that in a natural or spontaneous process there would be an increase in the entropy of the system. This is the most general criterion of spontaneity that thermodynamics offers however, to use this concept one must consider the entropy change in a process under the condition of constant volume and internal energy. Though infallible, entropy is thus not a very convenient criterion. There have, therefore, been attempts to find more suitable thermodynamic functions that would be of greater practical... 

An important use of the free energy function is to obtain a simple criterion for the occurrence of spontaneous processes and for thermodynamic equilibrium. According to the second law of thermodynamics,... 

The above form of the thermodynamic representation of the condition for the occurrence of a spontaneous process or of equilibrium is frequently used. 

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