Standardization of NaOH and Analyzing the Acetic Acid Content of VinegarDue 4/29/15Chm-222L-01
Abstract:The purpose of the NaOH experiment was to standardize a sodium hydroxide solution by using it to titrate a solution of potassium hydrogen phthalate. The purpose of the vinegar experiment was to determine the morality and mass percent of acetic acid in a vinegar sample, by titrating it with a standard sodium hydroxide solution. The standard solution was prepared by a primary standard(KHP) which was carefully weighed, dissolved, and diluted accurately to a known volume. Its concentration can be calculated from that data. The average molarity of the standardized NaOH solution was 0.482 mol/L. The percenterror for the average molarity was 3.6%. The average molarity of acetic acid was 0.491 mol/L. The average mass percent of acetic acid in the sample was 2.95g. The method used to standardize the NaOH solution is titrating with KHP that was been dissolved in water. The following equation is used to calculate molarity of a solution M1V1 = M2V2[ CITATION DSp15 \l 1033 ].Background:To standardize a solution means the concentration(molarity) is measured and the accuracy is guaranteed[ CITATION Yah \l 1033 ]. A titration is a method often used to determine the concentration of a solution of an acid or a base. It makes use of a known reaction between two chemicals, where one solution of unknown concentration is reacted with a precisely measured amount of another chemical whose molar concentration is known. A finely calibrated buret is used to accurately measure and deliver the second reactant to the flask and an indicator or pH Meter is used to detect the endpoint of the reaction[ CITATION Che \l 1033 ] Phenolphthalein is the indicator used to make the endpointof a titration visible. It signals when chemically equivalent amounts of each chemical are
combined, according to the exact molar ratio shown in the balanced equation for the reaction. This is known as the equivalence point. Molarity is the number of moles of solute per liter of solution [ CITATION Dic \l 1033 ]. The unit for molarity is moles/liters, which is moles of solute over Liters of solution [ CITATION LLa01 \l 1033 ]. The balanced chemical equation for lab1 is KHP(aq) + NaOH(aq) -> NaKP(aq) + H2O(l) and this is a double replacement reaction. These chemical equations were useful in calculating molarity becausethey gave the mole to mole ratio for each of the solutions.Procedure for Standardizing a NaOH Solution: I.Delivering the Water from a Buret1.A 400—mL beaker was labeled “Discard Solutions”. The stopcock of the buret wasclosed. The buret was filled with tap water from a beaker or wash bottle. The stopcock was opened to let the water drain through the tip into a beaker.
You've reached the end of your free preview.
Want to read all 10 pages?