Average rate of reaction

To facilitate the use of methanol synthesis in examples, the UCKRON and VEKRON test problems (Berty et al 1989, Arva and Szeifert 1989) will be applied. In the development of the test problem, methanol synthesis served as an example. The physical properties, thermodynamic conditions, technology and average rate of reaction were taken from the literature of methanol synthesis. For the kinetics, however, an artificial mechanism was created that had a known and rigorous mathematical solution. It was fundamentally important to create a fixed basis of comparison with various approximate mathematical models for kinetics. These were derived by simulated experiments from the test problems with added random error. See Appendix A and B, Berty et al, 1989. 

For the determination of rate of reaction at constant volume the concentration of a chosen reactant or product is determined at various time intervals. The change in concentration AC, for a given time interval At(t2 - q) is obtained. An average rate of reaction is then obtained by calculating AC/At. The smaller the value of At, the closer the value of the rate will be to the real rate at time (q + t2)l2 because... 

The rate of reaction decreases during the course of the reaction. The rate that is calculated above can be expressed as the average rate of reaction over a given time frame or, more commonly, as the initial reaction rate—the rate of reaction at the instant the reactants are mixed. 

Let us calculate the average rate of reaction in 30 - 90 minutes by using Graph 1. The average rate of reaction during the time interval from 30-90 minutes in terms of decreasing concentration of N2O5 ... 

Let us assume that 5.4 g of Al metal is dipped into 400 mL HCI solution. If after 1000 seconds, all the Al metal is consumed, what would be the average rate of reaction in terms of rate of appearance of AICI3 in M/s ... 

In defining precisely the criterion of reactor output, it is convenient to use one particular reactant as a reference rather than the product formed. The distinction is unimportant if there is only one reaction, but is necessary if more than one reaction is involved. The unit output WA of a reactor system may thus be defined as the moles of reactant A converted, per unit time, per unit volume of reaction space in calculating this quantity it should be understood that the total moles converted by the whole reactor in unit time is to be divided by the total volume of the system. The unit output is therefore an average rate of reaction for the reactor as a whole, and is thus distinct from the specific rate 9iA which is the local rate of reaction. 

The average rate of reaction is given by the arithmetic mean of the rates at 1 and 1 + 81. That is,... 

The rate o oxidation o ammonia at atmospheric pressure on single wires and ribbons has been determined as a function of a gas flow rate and catalyst size. In agreement with boundary layer diffusion theory the function rx, where r is the average rate of reaction/unit area, and x is the length of the surface measured in the direction of gas flow, is directly proportional to gas velocity. 

Average Rate of Reaction The average rate of reaction can be obtained by dividing the total change in concentration of reactant or product by the elapsed time. 

Calculate the average rate of reaction of C during this time interval. 

What is the average rate of reaction for the decomposition of N205 overall ... 

It was noted above that the curves in this figure show that the reactions are at their fastest at the beginning. When making comparisons between average rates of reaction it is this initial period of a reaction that is of most interest so ... 

The same amount of product (x) is formed each time, Le. it is constant. Average rate of reaction = xlt... 

The average rate of reaction is inversely proportional to the time taken to produce a given amount of product. 

NO2 and CO are consumed as NO and CO2 are produced. If a probe can measure the NO concentration, the average rate of reaction can be estimated from the ratio of the change in NO concentration A[NO] to the time interval At ... 

This estimate depends on the time interval At that is selected, because the rate at which NO is produced changes with time. From the data in Figure 18.3, the average rate of reaction during the first 50 s is... 

The rate of oxidation reaction under specific reservoir conditions is not stable. Average rate of reaction is generally determined by the ratio of difference between the final concentration of products (C2) and the original concentration of products (Ci). This change is measured during the time interval (ti, T2) in which this reaction was taking place, that is ... 

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