Equilibrium Concentration Of Equilibrium

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Introduction

Equilibrium is the concept that in a chemical reaction where both the forward and reverse reactions occur, equilibrium is reached when both reactions are occurring at the same rate, thus once a reaction is at equilibria both the forward and reverse reactions are occurring at the same rate. For a given Chemical Equilibrium at a given temperature, keq can be calculated that will be constant no matter the initial values of the reactants and products. For a reaction: the equilibrium constant, . When a reaction has not yet equilibrium, or to test whether it has, an equilibrium quotient can be obtained using the same formula to obtain the reaction quotient, to determine whether a reaction will proceed or isf it is at equilibrium.
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So the equation is where A is absorbance, is the absorbtivity constant, b is the path length of light, and c is the concentration of the solution. This part of the experiment used known concentrations of Fe(SCN)2+ in order to calculate the absorptivity constant. The concentration of Fe(SCN)2+ was obtained by reacting Fe3+ with huge excesses of SCN-, because since the value of SCN- is so large, we can assume that the reaction goes to completion in regards to Fe3+, and thus the initial concentration of Fe3+ is the same as the equilibrium concentration of Fe(SCN)2+. Using this knowledge, a spectrometer was used to calculate the absorbance of solutions of various concentrations of Fe(SCN)2+ at its max of 473.3 nm. The data points were then used to make a graph of Absorbance vs. concentration, with the slope of the linear regression of these points being equal to the absorptivity constant, since according to Beer’s law, and b in our case was …show more content…
This was done by reacting varying concentrations of the reactants together, and measuring the resulting product with a spectrophotometer. The initial concentrations of the reactants were concentrated by using the equation C1V1=C2V2, going from the stock solution to what was put into the reaction. The final concentrations were then calculated by using a spectrometer to measure the absorbance of Fe(SCN)2+, then using Beer’s law with our experimentally determined value of . Then, using an ICE table it was determined that the magnitude of change in concentration of the reactants was the same as the change of the products, so the final concentration of Fe(SCN)2+ was subtracted from the initial concentration of the reactants to find their final concentration. These concentrations were then used to find the k, with

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