Experiment 2- Homogenous Chemical Equilibrium

Experiment 2- Homogenous Chemical Equilibrium - Experiment...

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Experiment 2: Homogenous Chemical Equilibrium Abstract The equilibrium constant ( K c ) of the esterification of ethanol and acetic acid to produce ethyl acetate and water was determined. Five trials were performed, each with a different initial concentrations to prove that the equilibrium constant was independent of what was present initially. The titrant used was NaOH which was standardized against the primary agent KHP to determine the [NaOH] which was 1.56 M NaOH. The NaOH was then used on the five different flasks b, c, d, e, and f to determine the equilibrium constants which were 6.06, 5.85, 5.42, 6.20, and 4.47 respectively. The average equilibrium constant was 5.60 ± 0.70. Introduction A single headed arrow is used in chemistry to show that a reaction has gone to completion. But in some reactions a reaction does not go to 100% completion which is why a double headed arrow is used to show that products and reactants coexist in the same solution. It is important to note that the solution can have a lot of product and little reactant because the reaction was close to completion or that the solution can have a lot of reactant and little product because the reaction is not favorable and thus non-spontaneous. One crucial condition that could determine the spontaneity is the initial concentrations of the products and reactants in the solution .In spontaneous reactions, the amount of products and reactants will change until there is a state of no change. This is the point of equilibrium. A value which represents equilibrium can also be used to represent how far the reaction goes. This numerical way of showing how far a reaction goes can be expressed through the concentration values of the products and the reactants. Take for instance the following generic reaction: a A + b B c C + d D where [A], [B], [C], and [D] stand for the concentrations of the species at equilibrium and a, b, c, and d stand for the stoichiometric coefficients. Since the concentrations of the species are constant at equilibrium, this creates a constant value to represent these concentrations called the Law of Mass Action: [ ] [ ] [ ] [ ] b a d c c B A D C = K where K c is the equilibrium constant. This value can show how far a reaction goes by looking at its magnitude. By looking at the expression, when there is a high K c value, it means that there is a high concentration of products and that there is a low concentration of reactants thus the reaction almost went to completion. On the other hand, if there is a low K c value, this means that there is a higher concentration of reactants and there is a low concentration of reactants thus not much of the reactants converted to products showing that the reaction has a low degree of completion. Sometimes however, one wants to know which way a chemical reaction will go depending on the
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Experiment 2- Homogenous Chemical Equilibrium - Experiment...

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