Excess, reactants

Reactant Excessively mixture leaner or richer mixture... 

Attainment of abnormal reaction conditions, e.g. overpressure, over-temperature, segregation of reactants, excessive reaction rate, initiation of side reactions. 

In this example, oil is the limiting reactant. Excess hydrogen is easily recovered from a gas-phase reactor, so margarine manufacturers make the oil the limiting reactant to ensure complete conversion of oil into margarine. The excess H2 gas is recovered and used again in a subsequent reaction. 

Fig. 9.4. Typical tensimetric titration curve. Total pressure in the tensimeter is plotted against the mole ratio of BFj added to reactant. In this case the solvent was toluene which was maintained at — 78°C for each pressure measurement. The horizontal portion of the pressure curve originates from the low toluene vapor pressure at this temperature. Above the I i ratio of reactants, excess BFj is present and the pressure increases steadily with each addition of BFj.

What is meant by limiting reactant Excess reactant ... 

In industrial reactors you will rarely find exact stoichiometric amounts of materials used. To make a desired reaction take place or to use up a costly reactant, excess reactants are nearly always used. This excess material comes out together with, or perhaps separately from, the product—and sometimes can be used again. Even if stoichiometric quantities of reactants are used, but if the reaction is not complete or there are side reactions, the products will be accompanied by unused reactants as well as side products. In these circumstances some new definitions" must be understood ... 

The Sn and products were obtained by exhaustive electrolysis at Epa + 0.1 V The oxidation products were analyzed by cyclic voltammetry, GC/MS and H NMR Blank reactions (without oxidation of mixture) led to less than 10% yields of substitution products This yield is calculated on the o-complex formed. The remainder relates to recovered reactants Excess of the cyanide can be eliminated by electrochemical oxidation at 1.33 V... 

Compare that needed amount with the given amount in the problem statement. There will be more than enough of one reactant (excess) and less than enough of the other (limiting). 

Tojo, C., Blanco, M.C., and L6pez-Quintela, M.A. 1998. The influence of reactant excess and film fiexibility on the mechanism of nanoparticle formation in microemulsions A Monte Carlo simulation. Langmuir, 14, 6835-6839. 

Bread Peanut Butter Sandwiches Limiting Reactant Excess Reactant... 

The theoretical point to be discussed here is this In a back titration, two species exhibiting the same acidic or basic property are present in the titration vessel—the reactant excess, which is acidic or basic, and the conjugate form of the titrand. The problem is to neutralize the first species without neutralizing the second ... 

HK for a type Ij system, we have the foUowing two options for each choice 1) heavy reactant excess versus light reactant excess and 2) direct versus indirect separation sequence. This leads to four design alternatives as shown in Figure 17.19. For the case in which the heavy reactant (HHK) is in excess, we have three components (LLK, LK, and HK) leaving the reactive distillation column for further separation. Essentially, all of the LLK... 

Figure 17.20 shows that the heavy reactant excess design is favored over the hght reactant excess design by a factor of almost 30%. As for the column sequencing, the direct separation sequence is preferred over the indirect sequence. For the separation sequence, the LLK is boiled up twice for the indirect sequence as compared to that of the direct sequence where the LLK is only boiled up once. Therefore, we expect a lower separation cost using the direct sequence. 

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