Factors Influencing the Rate of Reaction

Every chemical reaction requires some time for its completion, but some reactions are fast and some are slow. Reactions between ions in solution without change in oxidation state are usually extremely fast. An example is the neutralization of a strong acid by a strong base, which proceeds as fast as the solutions can be mixed. Presumably nearly every time a hy-dronium ion collides with a hydroxide ion reaction occurs, and the number of collisions is very great, so that there is little delay in the reaction. 

The formation of a precipitate, such as that of silver chloride when a solution containing silver ions is mixed with a solution containing chloride ion, may require a few seconds, to permit the ions to diffuse together to form the crystalline grains of the precipitate  

An example of a reaction which is extremely slow at room temperature is that between hydrogen and oxygen  

A mixture of hydrogen and oxygen can be kept for years without appreciable reaction. If the gas is ignited, however, a very rapid reaction— an explosion— occurs, because of the energy liberated. 

A reaction that takes place in a homogeneous system (consisting of a single phase) is called a homogeneous reaction. The most important of these reactions are those in gases (such as the formation of nitric oxide in the electric arc. No + Oo 2NO) and those in liquid solutions. 

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The mechanism of activation of 8.137 in Fig. 8.13,a was shown to be an intramolecular nucleophilic attack by the phenolate ion at the carbonyl C-atom. Consequently, the rate of reaction increased linearly with pH, plateauing beyond 8-9. The major factor influencing the rate of reaction was the acidity of the leaving ROH, with tm values at pH 10 and 25° ranging from 290 d... 

Along with substrate concentration, the pH value is an important factor influencing the rate of reaction. Interestingly enough, a protease may have a different pH optimum for degradation and for resynthesis of... 

The factors influencing the rate of reaction between TAED and the persalt are as follows ... 

Table 18.1 Factors which Influence the Rate of Reaction of Particles...

Results from equilibrium modelling indicate that the extent of mineral trapping depends strongly on the fugacity of C02. Consequently, the extent of mineral trapping is sensitive to the rate of mineral-brine-C02 reactions relative to the rate of flow and dispersion of C02 away from the site of injection. Reactions must be fast enough to reach carbonate phase saturation before the C02 is overly diluted by outward radial flow, dispersion, and diffusion. The rates of reaction and the factors that influence the rates of reaction must be better constrained. 

An additional factor was found to influence the rate of reaction in the experiments involving tetrakis ( -mercaptoethylamine) trinickel (II) ion. The addition of nickel chloride retarded the process. Methanol was used as the solvent to demonstrate that the dependence was actually due to the presence of nickel ion and not an ionic strength effect. Magnesium chloride accelerates the rate slightly, while nickel ion greatly retards the rate of reaction. This effect was studied in greater detail, but solubility requirements necessitated the use of a water-methanol mixed solvent. A solution of 5.5M water in methanol was found to be satisfactory to obtain the necessary solubilities of complex and nickel chloride. 

In Chap. 2, the analysis of diffusion-limited reaction rates of Smolu-chowski, Collins and Kimball, and that of Noyes is followed. The considerable literature on reaction rates between solute species is also presented. Additional and important other factors which influence the rate of reaction are a coulomb interaction between reactants, long-range energy or electron transfer and an angular dependence of the rate of reaction. These topics are considered in the Chaps. 3—5. The experimental and theoretical work are compared and contrasted. When the reactants are formed in pairs (by bond fission of a precursor), the rate or probability of recombination can be measured and is of considerable interest. Chapters 6 and 7 discuss the theoretical aspects of the recombination of neutral and ionic radical pairs and also appeal to the extensive literature on the experimentally measured rate of recombination. The weaknesses of this theoretical... 

The important factors influencing the rates of enzymatic reactions are the concentrations of substrates and enzyme, as well as factors such as pH, temperature, and the presence of cofactors and metal ions. A study of these factors is important. In a pragmatic sense, there may be occasions when one needs to optimize the rate of a particular reaction. A study of the way the rate depends on experimental variables may also allow one to discriminate between possible models that attempt to predict how the enzyme may function, i.e., its mechanism. 

Xenobiotics are biotransformed by phase I enzymes and phase II conjugation reactions to form a variety of metabolites that are generally more water-soluble and less toxic than the parent compound. Occasionally, the enzymic action of phase I or II systems leads to the formation of unstable intermediates or reactive metabolites that are toxic or carcinogenic. Many physiological factors influence the rate of xenobiotic metabolism and the relative importance of different pathways of metabolic activation or detoxication. 

The rates of the forward (Ni-Rh) and reverse (H-R2Ni) ion-exchange reactions are very different (Fig. 17) since in these instances the selectivity is changed strongly with the solution concentration (see Ni/H exchange isotherms in Fig. 18). Both concentration and selectivity factors influence the rate of the Ni/H exchange. 

Factors influencing the rate of chemical reaction are surface tension polarity of the organic solvent acid-base properties of the aqueous phase relative rate of hydrolysis and other side reactions (salt formation, etc.) rate of separation of polymer out of solution rate of removal of side products of the reaction. 

A final factor influencing the rates of diagenetic reactions (solution, reprecipitation, recrystallization) in marine siliceous deposits is the porosity and permeability of the sediment. In studies of radiolarian cherts from Italy, Thurston (1972) found that the effects of diagenetic processes were least in... 

Concentration molecules must collide to react. A major factor influencing the rate of a given reaction is reactant concentration. A reaction can occur only when the reactant molecules collide. The more molecules present in the... 

There are several factors which influence the rate of reaction in a given system. Some depend on system characteristics which cannot be controlled during the cleaning operation operational-procedure factors are controllable. The first category includes sodium quantity, sodium surface-to-volume ratio, and presence of undrainable sodium pockets. 

The answer is D. This question tests your basic understanding of the factors that affect the rate of reactions. All the listed factors can influence the rate of reactions. 

A number of factors influence the rate of a chemical reaction. The concentration of reactants present is one critical factor, and the experimental determination of this effect results in an expression referred to as the rate law. We can work with rate laws in either of two forms the differential rate law and the integrated rate law. The differential rate law tells us the rate if we know the appropriate concentrations, whereas the integrated rate law predicts the concentration of a reactant as a function of time. 

The radiation chemistry of polymers is an extremely rich field of study, both from an intellectual and a practical viewpoint. The very large body of research devoted to this field is testament to this fact. The overall outcome of this work is a clear understanding of the effect of radiation on this class of materials, and the factors which influence the rates of reaction and the product distribution. These include factors intrinsic to the polymers, and extrinsic factors more readily imder the control of the experimental scientist or engineer. These are summarized below. 

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