6. Determine the amount of sample to analyze: a. The measuring range of the bure
ID: 702306 • Letter: 6
Question
6. Determine the amount of sample to analyze: a. The measuring range of the burette in this experiment is O to 5 mmoles of acidic hydrogen. Decide how many mmoles of acidic hydrogen you want in your instrument friendly sample. b. Calculate the volume of vinegar that should be used as your instrument friendly sample. Assume vinegar is a 5wt% aq solution of acetic acid, that each acetic acid molecule contains one acidic hydrogen, and that the density of the vinegar is 0.96g/mL. c. Describe how the vinegar volume calculated in step "b" could be delivered to the IFS flask using 1, 2 and 5 mL classical pipettes. d. Describe how the vinegar volume calculated in step "b" could be delivered to the IFS flask with a micropipette. NOTE: If you need to modify the vinegar volume in the IFS up or down to simplify the transfers in either step c or d then do so. 7. Set up a sample prep equation: In this lab you titrate vinegar directly. No dilutions are needed. Because of this the sample prep equation contains only the raw sample concentration, unit conversion factors (each acetic acid molecule has one acidic hydrogen), and the volume of vinegar present in the IFS. Using these factors set up a sample prep equation that relates Ces-the concentration of acetic acid in the raw sample in units of %weight acetic acid in vinegar, to Ors-the quantity of acidic hydrogen (mmolesacidic hydrogen) in the instrument friendly sample. 8. Read the appendix: What is the meaning of the term "standardization"? 9. Read the appendix: For what types of compounds is the method of standardization most useful? Lab 6Explanation / Answer
8) Standardization is the process of determining the exact concentration of a solution .Titration is one type of analytical procedure often used in standardization .In a titration,an exact volume of one substance is reached with a known amount of another substance .
The point at which the reaction is complete in a titration is referred ta as the endpoint .A chemical substance known as an indicator is used to indicate the endpoint .The indicator used in this experiment is phenolphthalein .Phenolphthalein ,an organic compound is colories in acedic solution and pink in basic solution.
9)
The experiment involves two separate acid base standardization procedures.In the first standardization the molarity of a sodium hydroxide solution will be determined by titrating a sample of potassium acid phthalate with the NAOH .In the second procedure the standardized NAOH will be used to determined the molarity of a hydrochloric solution (HCL).
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