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Unformatted text preview: Experiment 16 Identification of an Unknown Acid Summer 2010 Name TD Khang Lab Section 409 Point Summary (See Blackboard for detailed grading rubric) Superior Excellent Satisfactory Fair Poor Omitted Introduction Purpose of Report Goals of Experiment Materials and Methods Results and Discussion Description of data Data Tables Data Table Titles Graphs Figure Captions Sample Calculations Systematic Error Random Error Discussion of discrepancies Other Unknown Identification TOTAL POINTS TA Comments/Suggestions: C HEMISTRY 102L R EPORT T EMPLATE EXPT. Identification of an Unknown Acid 16 16 Introduction The purpose of this experiment is to determine the identity of an unknown acid through an acid- base titration. The base involved is a sample prepared last experiment of NaOH. The analysis of titration curve of the acid-base titration will allow experimenters to determine the identity of the unknown acid. The goals of the experiment were to determine the half-equivalence point and the molar mass to ultimately determine the identification of the unknown acid. The half-equivalence point is halfway between equivalence points. The half-equivalence was the point at which pH of the acid is equal to the pKa of the acid. Another goal was to determine the molar mass of the unknown acid from the titration curve. This was completed by obtaining the volume of the NaOH titrated at the equivalence point. The equivalence point is where the moles of acid equals the moles of base. The volume at equivalence point is determined by the 1 st derivative plot. He equivalence point is the location of the curve which has the greatest slope. The volume at equivalence point and the concentration of NaOH were used to determine the moles of acid involved. The mass of unknown acid used and the moles of acid involved were used to determine the molar mass. Materials and Methods A buret was conditioned and filled with the NaOH solution prepared and standardized last experiment. A mass of 0.3 to 0.4 grams of the assigned unknown acid was weighed and recorded in Data Table 1. The measured amount of unknown acid was placed into a clean 100-mL beaker. The sample of unknown acid was dissolved with 25 mL of ethanol in a beaker. A stir bar was placed in the solution and the solution was stirred until the solid sample of acid was completely dissolved. As the solution was stirred, 25 mL of distilled water was added to the beaker and the resulting solution was stirred for another...
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