Revised 24 Jul Accepted 02 Aug Published 09 Oct Abstract Competitive-consecutive and competitive-parallel reactions are both mixing sensitive reactions where the yield of desired product depends on how fast the reactants are brought together.
Introduction Mixing-sensitive reactions are reactions which are particularly sensitive to the rate at which the reactants are brought together, that is, how fast they are mixed. Table 1. Table 2. Stoichiometries of reaction schemes and the corresponding dimensionless reaction rate ratio for the eight different C-C reactions. Da was always Da. Case Reaction scheme Da 1 1, 1 2 1, 2 3 2, 1 4 2, 2. Table 3. Table 4. System of equations for competitive-consecutive reaction scheme, to be used with 1 and 2.
Table 5. System of equations for competitive-parallel reaction scheme, to be used with 1 and 3. Figure 1. Initial conditions for a C-C and b C-P reaction scheme simulations. Figure 2. Plots of yield of versus Da for decreasing ratios for the C-C cases.
C-C stoichiometry Case 2: P;. Figure 3. Plots of Yield of versus for two sample C-C stoichiometries. The curves represent the different Da. Curves for lie exactly under the curves for. Figure 4. Plots of yield of versus for various Da at for C-C cases. Figure 5. Figure 6. Plots of yield of versus Da for decreasing ratios for the C-P cases. C-P stoichiometry Case 1: P;. Figure 7. Plots of yield of versus for two sample C-P stoichiometries. Figure 8. Figure 9.
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Usually, an increase in temperature is accompanied by an increase in the reaction rate. Temperature is a measure of the kinetic energy of a system, so higher temperature implies higher average kinetic energy of molecules and more collisions per unit time.
A general rule for most not all chemical reactions is that the rate at which the reaction proceeds will approximately double for each degree Celsius increase in temperature. Once the temperature reaches a certain point, some of the chemical species may be altered e.
The rate of a chemical reaction depends on the medium in which the reaction occurs. It may make a difference whether a medium is aqueous or organic; polar or nonpolar; or liquid, solid, or gaseous.
Reactions involving liquids and especially solids depend on the available surface area. For solids, the shape and size of the reactants make a big difference in the reaction rate. Catalysts e. Catalysts work by increasing the frequency of collisions between reactants, altering the orientation of reactants so that more collisions are effective, reducing intramolecular bonding within reactant molecules, or donating electron density to the reactants.
The presence of a catalyst helps a reaction proceed more quickly to equilibrium. Aside from catalysts, other chemical species can affect a reaction. The number of hydrogen ions the pH of aqueous solutions can alter a reaction rate. Other chemical species may compete for a reactant or alter orientation, bonding, electron density , etc. Increasing the pressure of a reaction improves the likelihood reactants will interact with each other, thus increasing the rate of the reaction.
As you would expect, this factor is important for reactions involving gases, and not a significant factor with liquids and solids.
Mixing reactants increases their ability to interact, thus increasing the rate of a chemical reaction. The chart below is a summary of the main factors that influence the reaction rate.
There is typically a maximum effect, after which changing a factor will have no effect or will slow a reaction. For example, increasing temperature past a certain point may denature reactants or cause them to undergo a completely different chemical reaction. Actively scan device characteristics for identification. To gain an understanding of the four main factors that affect reaction rate. Reactions occur when two reactant molecules effectively collide, each having minimum energy and correct orientation.
Reactant concentration, the physical state of the reactants, and surface area, temperature, and the presence of a catalyst are the four main factors that affect reaction rate. Previous: Chapter Next: Reaction Rates.
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