Search results
Results From The WOW.Com Content Network
One reactant (A) is chosen, and the balanced chemical equation is used to determine the amount of the other reactant (B) necessary to react with A. If the amount of B actually present exceeds the amount required, then B is in excess and A is the limiting reagent. If the amount of B present is less than required, then B is the limiting reagent.
Thus, to calculate the stoichiometry by mass, the number of molecules required for each reactant is expressed in moles and multiplied by the molar mass of each to give the mass of each reactant per mole of reaction. The mass ratios can be calculated by dividing each by the total in the whole reaction.
The stoichiometry of a chemical reaction is based on chemical formulas and equations that provide the quantitative relation between the number of moles of various products and reactants, including yields. [8] Stoichiometric equations are used to determine the limiting reagent or reactant—the reactant that is completely consumed in a reaction ...
For overall selectivity the same problem of the conflicting definitions exists. Generally, it is defined as the number of moles of desired product per the number of moles of undesired product (Definition 1 [3]). However, the definitions of the total amount of reactant to form a product per total amount of reactant consumed is used (Definition 2 ...
where denotes the number of moles of the reactant or product and is the stoichiometric number [4] of the reactant or product. Although less common, we see from this expression that since the stoichiometric number can either be considered to be dimensionless or to have units of moles, conversely the extent of reaction can either be considered to ...
where A and B are reactants C is a product a, b, and c are stoichiometric coefficients,. the reaction rate is often found to have the form: = [] [] Here is the reaction rate constant that depends on temperature, and [A] and [B] are the molar concentrations of substances A and B in moles per unit volume of solution, assuming the reaction is taking place throughout the volume of the ...
If we assume a local steady state, then the rate at which B reaches is the limiting factor and balances the reaction. Therefore, the steady state condition becomes 1. [] = where is the flux of B, as given by Fick's law of diffusion, 2.
Standard enthalpy of hydrogenation is defined as the enthalpy change observed when one mole of an unsaturated compound reacts with an excess of hydrogen to become fully saturated. The hydrogenation of one mole of acetylene yields ethane as a product and is described by the equation C 2 H 2 (g) + 2 H 2 (g) → C 2 H 6 (g).