Extent of a Chemical Reaction

Once the chemical formula is selected, the progress of the chemical reaction can be quantified. It is convenient to express the progress of the chemical reaction in terms of the chemical formula selected. To do so we define a quantity called the reaction extent. 

Definition The extent of a chemical reaction is one unit of file chemical formula selected. 

The extent represents a certain amount of mass, and its units are mole extent. For example, for Reaction 2.2.1, one extent means fiiat one mole of CO reacts with half a mole of O2 to form one mole of CO2 and it represents 44 units of mass. 

The extent of a chemical reaction is determined from the number of moles of any species, say species j, formed (or depleted) by the reaction 

Moles of species j formed by the reaction rij — n Stoichiometric coefficient of species j 

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What are the properties of a system at equilibrium What factors affect the extent of a chemical reaction ... 

What factors determine the direction and extent of a chemical reaction Some reactions, such as the combustion of hydrocarbon fuels, go almost to completion. Others, such as the combination of gold and oxygen, occur hardly at all. Still others—for example, the industrial synthesis of ammonia from N2 and H2 at 400-500°C— result in an equilibrium mixture that contains appreciable amounts of both reactants and products. 

The two people were exposed to the same chemical, phenol, but one was more concentrated than the other. Concentration makes a difference to the speed and extent of a chemical reaction. The chemical worker had been hit by a very concentrated solution of phenol and Lister by a fine spray of dilute phenol solution. 

If a system is stable with respect to diffusion, a chemical reaction is also stable in the vicinity of equilibrium. The reaction rate is ./, de/dt, where e is the extent of a chemical reaction. The time change in the number of molecules N due to an elementary reaction is dN = v de. In terms of the small fluctuations 8e of the extent of the reaction, the stability condition becomes... 

Extent of a chemical reaction, mole extent (Eq. 2.3.1) Reaction extent per unit time, mole extent/time (Eq. 2.3.10) Molar fraction, dimensionless... 

Equilibrium Constants Reflect the Extent of a Chemical Reaction... 

On-line analysis of physical parameters, such as temperature, pressure, volume, density, etc., may also reflect the extent of a chemical reaction in addition to revealing the state of the reactor. 

In this formulation the key realization is that d represents the extent of a chemical reaction and hence that d/xl big is good [2, 3]. One-sided functional derivatives are once again required since p[N,vo r)] is discontinuous at integer values of N [6, 26 28]. Use of the definitions... 

The distribution of residence time provides information how long different parts of the resin reside in the processing equipment. The spread of the residence times reflects, on the one hand, the uniformity of flow inside the processing unit and, on the other, the quality of the product, the degree of mixing, or the extent of a chemical reaction. 

There are many situations in which a chemical system is not at thermal equilibrium therefore, a temperature cannot be defined, nor can it be used to characterize the state of the system and its evolution. Under these conditions, the rate constant k T) cannot be used to characterize the chemical reaction consequently, one needs other parameters to describe the extent of a chemical reaction. This is particularly true in molecular reaction dynamics, the field that studies what happens at the molecular level during an elementary chemical reaction. 

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