Titration of Acetic Acid

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Titration for Acetic Acid in Vinegar

Purpose:
The Primary Purpose of this Experiment is to Determine the Percent Content of Acetic Acid in a Household Bottle of President’s Choice Vinegar, using Titration Techniques. In addition, a Secondary Purpose for this Experiment that Derives Directly from the Primary Purpose is to Gain Hands On Experience in Titration Techniques, as a Vital Tool in our Quest to Understanding the Chemical Aspect of the World around Us.

Procedure
Conducting a Titration is the Process of Applying a Balanced Chemical Equation to Determine the Volume of a Solution with an Unknown Molarity or Concentration that is Need to React with a Pre-Determined Amount of a Second Solution of a Known Molarity and Concentration. In order to Achieve a Proper Titration, however, a great deal of measuring, preparation, and precision was required from me; beginning with arranging the equipment so that the Stop Cock Tip of the Test Tube located in the Elevated Clamp Handle is located approximately one to two centimeters above the beaker where the Color Change in the Titration Indicator, in this case Phenolphthalein, is to be observed. I then proceeded to Pour and Measure 9.9 mL of 0.5 Sodium Hydroxide Solution, taking care to allow a few drops of the Sodium Hydroxide Solution to drip into the Beaker, in order to Ensure a More Accurate Reading of the Volume of Solution Used Once the Experiment was Preformed. Once the Beaker was rinsed with Distilled water and the Initial Volume of Sodium Hydroxide was Recorded, the Experiment proceeded by Pouring and Measuring 5 mL of President’s Choice Vinegar into the Beaker and Subsequently adding two drops of the Titration Indicator, Phenolphthalein to the Beaker. Now Came the Reaction Portion of the Experiment, where I took care to Open the Stopcock with Such a Steady Flow that it would Add Only One Drop of Sodium Hydroxide ever Two to Three Seconds, while Simultaneously Counting and Keeping Track of How Many Drops of Sodium Hydroxide had been placed into the Beaker. Once, I observed a slight color change, I closed the Stopcock and Gently Swirled the Sample to Observe if the Color Change Remained. If it did not Remain, I Carefully Reopened the Stop Cock with a Steady Flow; I basically repeated this last step until the Color Change Remained for at least 30 seconds, making sure to achieve a balance of not over titrating, where too much sodium hydroxide has been added to achieve the color change nor under titrating, where too little sodium hydroxide had been added to the solution and the color change reaction did not remain for a significant amount of time. Finally, I Recorded the Final Volume of Sodium Hydroxide Solution and Calculated How Much Sodium Hydroxide was Utilized to Create this Reaction. I then repeated this Titration Process for Two More Trials, and Disposed of the Waste Down My Kitchen Sink, Taking care to Clean All My Equipment and Dispose of any Additional Acids and Bases by Running the Faucet for Three to Four Minutes after Pouring these Solutions down the Drain.

Data Table: Quantity of NaOH Needed to Neutralize 5 mL of President’s Choice Vinegar

Initial NaOH Reading Final NaOH ReadingVolume of NaOH Used Trial One9.9 mL1.9 mL8.0 mL
Trial Two9.9 mL2.1 mL7.8 mL
Trial Three9.8 mL1.9 mL7.9 mL
Average Volume of NaOH Used in Three Trials: 7.9 mL

Calculations:
1. Calculate the Average Number of mL of NaOH Used for the Three Trials and Record. (8.0 mL + 7.8 mL + 7.9 mL) = 7.9 mL of NaOH
3
2. Calculate the Normality of the Vinegar using the Previously Given Equation. Na= (Nb) (Volume b)
Volume a
1 mol of NaOH= 40 g NaOH
1 mmol of NaOH= 0.04 g NaOH
Na= (0.5 mmol/mL) * (7.9 mL of NaOH)
5.0 mL
Na= 0.79 mmol/mL of HC2H3O2
3. Calculate the Mass of the Acetic Acid in Grams Using the Previously Given Equation. Mass a= (Na) (GMWa)
1 mol of HC2H3O2= 60 grams
1 mmol of HC2H3O2= 0.06 grams
= (0.79 mol/L) * (60 g/mol) *Molarity...
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