Ionization Constant of a Weak Acid.docx - Experiment #2...

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Experiment #2Thanh HuynhMay 9, 2017Ionization Constant of a Weak AcidIntroduction:The concepts of acids and bases are defined by the Bronsted-Lowry acid-base theory. The abilityto donate protons determined the strength of an acid. Strong acid can be easily and completelyionized in solution while a weak acid can only partially do thatHA(aq) +H2O(l)+¿H3O¿(aq) +¿A¿(aq)The acid ionization constant (Ka) determined the degree of ionization of weak acid. Thisconstant is relied on the strength of the attraction between the cation and anion in the acidcompound (+¿H¿and¿A¿). The reaction would favor the forward direction if this attraction isweak. This also mean this acid is strong. On the other hand, if this attraction is strong, meaningthe acid is weak, the reaction would favor the reverse direction. The equation indicates the law ofmass action forKashown below:Ka=H¿+¿¿A¿¿¿¿¿=+¿H¿¿¿A¿¿¿¿In this experiment, the ionization constant of a weak acid was determined by calculation basedon the titration of it with the strong base, which is NaOH. Data were then collected throughLogger Pro which was connected with the computer. First, a standard solution of NaOH wasprepared and then would be used later to titrate the sample of weak acid. The equivalencevolume, at the first and second derivative was recorded through the graph of pH and volume ofNaOH. The half-equivalence volume of NaOH was then calculated by taking the volume of firstderivate and divided to two. Then the NaOH solution was standardized by diluting with water toabout 0.1M. The concentration of the 0.1M NaOH was determined by titrating against the KHP

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Term
Fall
Professor
NoProfessor
Tags
Proton, Bases, pH, Sodium hydroxide, Thanh Huynh

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