Chemistry Lab Experiment 6 Titration Of The Acetic Acid In Vinegar

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please find the attached Lab Chemistry manual report pages, I need to answer the questions which are post Lab 5 and pre lab 6. but Please I need them typing not hand written.

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Initially you will know the concentration of the standard sodium hydroxide solution and the volume of vinegar that you are titrating. After carrying out the titration you will also know the volume of NaOH that is needed to neutralize your given volume of vinegar. Using this information you can easily calculate the concentration of acetic acid in your vinegar. Because the reaction of acetic acid and sodium hydroxide occurs in a one to one molar relationship, HC,H,O2 + NaOH → NACH,02 + H2O the following simple relationship holds true when concentration is in terms of molarity: Volume NaOH (Concentration HC H202) = (Concentration NaOH) x Volume HC,H,02 This simple relationship works because the concentration in molarity (moles/liter) multiplied by a volume gives the number of moles for a compound, and the number of moles of HC H,02 must be equal to the number of moles of NaOH at neutralization. CAUTION: This particular relationship only works for reactions with a one-to-one stoichiometry; otherwise, you should work out the concentration of unknown using a complete dimensional analysis procedure. For example: If 34.50 mL of 0.2486 M NaOH is needed to titrate 10.00 mL of a HCl solution, what is the concentration of the HCI? HCI + NaOH → NaCl + H2O 34.50ml NaOH Concentration HC = 0.2486M NaOH x = 0.8577 M HCI 10.00ml HCI The stoichiometry of NaOH to HCI is 1:1; therefore we can use our simple relationship, and the concentration of the HCl solution is therefore 0.8577 M. Concept: You will determine the concentration of acetic acid in vinegar by titrating a sample of vinegar with a known solution of sodium hydroxide. Phenolphthalein will be used as an indicator dye to determine when the reaction is complete. In basic solutions phenolphthalein is pink, in acidic solutions it is clear. NaOH will be added to a known volume of vinegar containing a few drops of phenolphthalein. As the neutralization reaction is complete and the next drop of NaOH is added, the solution will go from acidic to basic and change color from clear to very light pink signaling the end-point of the titration. Knowing the volumes of vinegar and sodium hydroxide used and the concentration of the standard sodium hydroxide solution, the acetic acid concentration in the vinegar can be determined. 108 Titration of Vinegar EXPERIMENT #6: TITRATION OF THE ACETIC ACID IN VINEGAR Purpose: The purpose of this experiment is to determine the amount of acetic acid in vinegar by titrating it with a standard (known concentration) solution of NaOH in the presence of the acid-base indicator phenolphthalein. Special Apparatus and Chemicals: Standard NaOH Solution 10 mL Volumetric Pipet 50 mL Buret Dropper bottle with phenolphthalein 5% white vinegar Buret Clamp and Stand Discussion: The concentration of a solution is often determined by volumetric analysis in which a given volume of the solution, measured with volumetric glassware, is analyzed against a known substance or solution. In our experiment we will start with a known volume of the vinegar whose concentration is to be determined, and amounts of a standard solution of sodium hydroxide of known concentration will be added incrementally until the reaction (neutralization) is complete. This process of incremental addition until a complete reaction is achieved is called titration. The standard solution is referred to as the titrant and the substance being analyzed the analyte. The volume the titrant needed for neutralization is determined by using a buret. Before beginning this experiment be sure to read about using a buret beginning on page 31 of this manual. In this experiment you will be determining the concentration of a vinegar solution (dilute acetic acid) using a standardized solution of sodium hydroxide. Because this and most other acid-base neutralizations occur with no visible reaction, an acid-base indicator such as phenolphthalein is used to give a visible sign that neutralization has occurred. Phenolphthalein is colorless in acidic or neutral solutions, but pink in basic solutions. Thus, by putting phenolphthalein in our sample of vinegar that is being titrated, the initial solution is clear but becomes pink upon neutralization of the acetic acid and addition of excess sodium hydroxide. The stage at which the vinegar has been neutralized and one extra drop of titrant causes the indicator to change colors is called the end point. In very precise work, the sodium hydroxide itself would be standardized against a primary standard such as potassium hydrogen phthalate. Experiment 6 107 Procedure: Clean and prepare a buret according to the directions given in the section on "Measurement of Volume" in the beginning of this manual. Fill the buret with NaOH. Make sure no air bubbles are left in the tip of the buret. Be sure to write down the concentration of the NaOH and the initial buret reading. Read the buret to within +0.02 mL; remember to read from the bottom of the meniscus. CAUTION: NaOH may cause chemical burns. If any NaOH comes in contact with your skin or clothes, rinse the affected area immediately with large amounts of cold water. Pipet exactly 10 mL of white distilled vinegar into a clean 125 mL Erlenmeyer flask using a volumetric pipet . Note: Pipetting should never be done out of the original reagent bottle; in order to avoid contamination, transfer some of the liquid being pipetted to a small beaker or flask before pipetting. Add 10 mL of distilled water and 2 or 3 drops of phenolphthalein solution to the vinegar. You are now ready to begin the titration. (Note: It is often helpful to do an initial trial titration to find the approximate volume of titrant needed. Check with your instructor about doing a trial titration.) Begin the titration by letting a volume of sodium hydroxide run into the flask equal to the volume that you think is needed for neutralization minus 1 to 2 mL. You should now be within 20-40 drops of the end point (1 mL equals about 20 drops). Swirl the flask to mix the solution and then rinse down the walls of the flask with distilled water from a squirt bottle. Now add the sodium hydroxide drop by drop until the end point is reached. The sodium hydroxide should be added while maintaining a gentle swirling motion of the flask. The solution should be a very light shade of pink when the titration is finished. A piece of plain white paper placed under the flask is often helpful in determining when the end point is reached. Record the final buret reading. If you are unsure whether you have reached the end point, record the reading and then add one more drop. If you were at the end point, the extra drop will give the solution a very definite pink color. DISPOSAL: All solutions from this experiment may be safely disposed of down the sink with running water. Refill the buret with NaOH and rinse out the flask with distilled water. Repeat the titration three more times or as directed by your laboratory instructor. After you have collected a good set of data and with due regard for significant figures, calculate the acetic acid concentration in the vinegar for each trial; determine the average concentration of acetic acid using only the measurements that you are confident in (i.e. those in which you did not overshoot the endpoint); and determine the standard deviation for your concentration values. Experiment 6 109 Experiment #5 Problems 1. Suppose you have a solution that contain Ba?', Ag, and Fe' ions. When a solution of NaCl is added, a white precipitate is formed. The precipitate is filtered off. When a solution of Na SO, is added to the filtrate, another white precipitate is formed. Again, this precipitate is filtered off. When a dilute NaOH solution is added to the last filtrate, a brown precipitate is formed. Write the chemical formulas of the above precipitates. Which ions are present in each of the precipitates. 2. Your instructor has given you three unlabeled test tubes. One test tube contains a sodium chloride solution, another test tube contains a vinegar solution, and the third test tube contains household ammonia solution. Use litmus papers to identify the solutions in the test tubes. 3. Write balanced net ionic equations for the reactions of milk of magnesia with sulfuric acid and vinegar with household ammonia. Experimenu 5 103 REPORT SHEET: IONIC REACTIONS IN SOLUTION Name: Section: Precipitation Reactions Date: Fe(NO3)3 Ba(NO3)2 Pb(NO3)2 yes Clonely Naci AgNO3 Yes Cloudy Agel No Clean Ne ppt orang. color formula امن و No ppt Na2SO4 No Clonely No clean yes white color formula Yes Yes Ppt NaOH علم yes Brown cloudly Brown color formula ppt Na2CO3 yes senangley yes white yes Brown color cloudy formula ppt Epsom salt yer while NO clear yes white In No rust color formula Conclusions about the composition of the epsom salt based on experimental results: celourat mostly clata Nothing tittle paricele floating Reaction of AgNO3 with tap water Explanation if reaction Experiment 5 101
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Titration can be defined as the slow addition of one known solution to another unknown solution
with a given volume in order to reach neutralization
End point- This is the point where all the all the titrant has reacted with the solution and is
usually denoted by color change
Standard Solution is a solution whose concentration is ...


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