Equilibrium constant change

The equilibrium constant for this system, like all equilibrium constants, changes with temperature. At 100°C, K far the N204-N02 system is 11 at 150°C, it has a different value, about 110. Any mixture of N02 and N204 at 100°C will react in such a way that the ratio (Eno /EnjO, becomes equal to 11. At 150°C, reaction occurs until this ratio becomes 110. 

The method of representing the equilibrium state The value of the equilibrium constant changes if the reversible reaction is considered to proceed in the reverse direction. For example, the reaction A + B C + D can also be written asC + D A+Bso that [A] [B]/[C] [D] = kr/kf = K. In this case the value of the equilibrium constant for the reverse reaction is given by K = 1/K. To avoid such confusion while applying the law of mass action, the concentrations of the products are always placed in the numerator and those of the reactants in the denominator. 

As you know, the value of the equilibrium constant changes with temperature, because the rates of the forward and reverse reactions are affected. 

Equilibrium Conversion. The equilibrium composition, as governed by the equilibrium constant, changes with temperature, and from thermodynamics the rate of change is given by... 

On integrating Eq. 15, we see how the equilibrium constant changes with temperature. When the heat of reaction AH, can be considered to be constant in the temperature interval, integration yields... 

Temperature changes affect not only systems at equilibrium but also the value of equilibrium constants. In fact, equilibrium constants changing with temperature is the reason that equilibria change with temperature. For example, consider Kgq for the ammonia synthesis equilibrium. 

Despite their success in giving the correct expressions for the mass action law, the empirical procedures leave unanswered numerous fundamental questions about chemical equilibrium. Why should the law of mass action exist in the first place, and why should it take the particular mathematical form shown here Why should the equilibrium constant take a unique value for each individual chemical reaction What factors determine that value Why does the value of the equilibrium constant change slightly when studied over broad ranges of concentration Why should the equilibrium constant depend on temperature Is there a quantitative explanation for the temperature dependence ... 

Remember that the value of an equilibrium constant changes only with temperature. 

The value of any equilibrium constant changes as the temperature changes. Changing the temperature of a reaction at equilibrium thus causes Q to differ from K, but this is now because has changed. The reaction then proceeds in the direction that moves Q toward the new value of K. As we will see in Section 17-13,... 

Equilibrium constants change with temperature in a way that depends on A// for the reaction. In accordance with Le Chatelier s principle, K increases with rise in temperature for an endothermic reaction, and decreases for an exothermic one. 

Each chemical reaction has a unique equilibrium constant value at a specified temperature. Equilibrium constants listed in the chemical literature are often reported at 25°C, to allow comparison of one system with any other. For any equilibrium reaction, the value of the equilibrium constant changes with temperature. 

Considering the effect of temperature, again with Cl, F and with H2O behaving as perfectly incompatible substances in the melt, variations in Cl F OH in apatite reflect nothing other than how equilibrium constants change with temperature (Piccoli and Candela 1994). 

Discuss in general terms the effect on the net amount of product when an additional amount of one of the reactants is added to an equilibrium system. Does the value of the equilibrium constant change in this situation ... 

Furthermore, there are situations where high concentrations of a second isomer can be detected by infrared (IR) at room temperature, but the equilibrium constant changes as the temperature is lowered such that the minor component can no longer be detected in the limiting low-temperature spectrum ( 46). 

The equilibrium constant changes with change in concentration or volume of reactants. 

We have noted that the equilibrium constant Kj for reaction depends only on the system temperature T and the standard state. Often, we need to determine how the equilibrium constant changes with temperature. For example, during a reactor design we routinely want to know whether product yield can be improved by an increase or decrease in operating temperature. Furthermore, many tables (discussed at the end of 10.4.2) give values for equilibrium constants only at selected temperatures then we must correct those values to the temperature of our situation. 

SECTION 15.3 The value of the equilibrium constant changes with temperature. A large value of indicates that the equilibrium mixture contains more products than reactants and therefore lies toward the product side of the equation. A small value for the equilibrium constant means that the equilibrium mixture contains less products than reactants and therefore lies toward the reactant side. The equilibrium-constant expression and the equilibrium constant of the reverse of a reaction are the reciprocals of those of the forward reaction. If a reaction is the sum of two or more reactions, its equilibrium constant will be the product of the equilibrium constants for the individual reactions. 

Changes in concentrations or partial pressures shift equilibria without changing the value of the equihbrium constant. In contrast, almost every equilibrium constant changes as the temperature changes. For example, consider the equihbrium established when cobalt(II) chloride (C0CI2) is dissolved in hydrochloric acid, HCl(aq), in the endothermic reaction... 

When we work with precipitation reactions like those in the previous example, we need to look up values for the equilibrium constants. But the values we find in a reference book typically refer to the opposite process—solubility. So we will need to know how an equilibrium constant changes if we modify the chemical equation to which it refers. 

It has also been suggested that the reduction by 1,4-dihydropyri-dine derivatives proceeds by a one-step hydride transfer mechanism (HT-mechanism), which seems to be contrary to the ET-mechanism described above. This assertion is mostly based on the results from the reduction of cationic substrates such as quinolinium salts, acridinium salts, and protonated Schiff bases (Srinivasan et al. 1982). For example, Ostovic et al. (1983) reported that the value of the kinetic isotope effect does not change significantly for the reactions with a series of substrates with which equilibrium constants change widely. 

Like any equilibrium constant, changes with temperature. 

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