Determination of the Concentration of Acetic Acid in Vinegar

Determination of the Concent symmetryn of acetic tart in Vinegar Lab Exercise 4 CHEM 1106 9/19/12 Purpose Standardize a sodium hydroxide resoluteness utilise a primary standard unpleasant. Determine the chiliad and the percent by mass of acetic pane in acetum by titration with the standardized sodium hydroxide upshot. Introduction Vinegar is a sheer solution containing acetic irate. Since vinegar has a low pH, it give the gate be titrated with a carnal.Titration is a order used in order to ascertain the amount of a constituent in a solution by measuring the volume of a known concentration of a reagent required to complete a reaction with it, typically using a burette. The compare point of a titration occurs when chemically equivalent amounts of acid and base are present. In this experiment, the equivalence point occurs when the breakwateres of acid in the solution equals the groynees of base added in the titration. A rapid change in pH with the small addition of acid or base is the indicator for acid-base equivalency.Accompanying material Vinegar Battery Statement of the ProblemUsing a pH meter and a graph of pH plotted versus the volume of base added, the equivalence point can be accurately found by finding the point that is in the middle of the vertical part of the curve. Once the equivalence point of the titration is known, the concentration of the sodium hydroxide can be determined. Sodium hydroxide is used to titrate vinegar so that the concentration of the vinegar is determined. The percentage of acetic acid in solution can be determined from the concentration of the vinegar. Procedure Part A Standardization of a Sodium hydroxide Solution 1. Prepare 150 mL of approximately 0. M sodium hydroxide solution from hale NaOH. The solution can be prepared in a beaker, it is not necessary to use a graduated cylinder or a volumetric flask because the NaOH solution will be standardized. 2. conceive a 150-mL beaker and record the mass to the neares t 0. 001 g. Add approximately 0. 5 grams of potassium hydrogen phthalate (KHP) to the beaker. lay the mass of the beaker and KHP to the nearest 0. 001 g. organise the mass of KHP by difference and record it. Add approximately 50 mL of distilled water to the beaker. Stir the solution until the KHP has dissolved completely. 3.Record a titration curve using the MeasureNet pH study and drop counter. (See cecal appendage F) 4. Repeat steps 2 and 3. 5. From the plots, determine the volume of NaOH required to neutralize the KHP solution in each titration. Record the volumes. 6. Calculate the molar concentration of sodium hydroxide. Part B Determination of Acetic Acid Concentration in Vinegar 7. Transfer 2. 0 mL of vinegar to a clean, prohibitionist 150 mL beaker using a 10-mL volumetric pipet. Add sufficient water, 50 mL, to cover the pH electrode tip during the titration. 8. Record a titration curve using the MeasureNet pH probe and drop counter. See Appendix F) 9. From the plots, d etermine the volume of NaOH required to neutralize vinegar in each titration. Record the volumes. 10. Calculate the molarity of acetic acid in vinegar. 11. Calculate the percent by mass of acetic acid in vinegar. Data Part A Standardization of a Sodium Hydroxide Solution Mass of beaker97. 47 g Mass of beaker + KHP97. 99 g Mass of KHP0. 52 g Volume of NaOH to neutralize the KHP solution7. 755 mL mebibyte of sodium hydroxide 0. 535 M NaOH Part B Determination of the Concentration of Acetic Acid in Vinegar Volume of NaOH required to neutralize vinegar3. 18 mL Molarity of acetic acid in vinegar0. 8515 M CH3COOH Percent by mass of acetic acid in vinegar5. cxv% Equations (1) Molarity (M) = moles of solute/liter of solution (2) Percent solute= (grams of solute/grams of solution) x 100% (3) NaOH (aq) + CH3COOH (aq) NaCH3CO2 (aq) + H2O (l) (4) pH = -logH3O+ (5) KHC8H4O4 (aq) + NaOH (aq) KNaC8H4O (aq) + H2O (l) Calculations Part A Standardization of a Sodium Hydroxide Solution Calculate t he mass of KHP (Mass of Beaker + KHP) Mass of Beaker = Mass of KHP 97. 99g 97. 47g = 0. 52g Calculate the molarity of sodium hydroxideMoles of KHP = g/MW = 0. 52g/204. 22g = 0. 002546 mol KHP Equation 5 = 11 ratio 0. 002546 mol KHP x 1 mol NaOH/1mol KHP = 0. 002546 mol NaOH Equation 1 = 0. 002546 mol/0. 004755 L = 0. 535 M NaOH Part B Determination of the Concentration of Acetic Acid in Vinegar Calculate the molarity of acetic acid in vinegar 3. 318 mL/1000 = 0. 00318 L NaOH 0. 00318 L NaOH x 0. 535 mol/1L NaOH = 0. 001703 mol NaOH Equation 3 = 11 ratio 0. 001703 mol NaOH x 1 mol CH3COOH/1 mol NaOH = 0. 001703 mol CH3COOH 2. 0 mL CH3COOH/1000 = 0. 0020 L CH3COOH Equation 1 = 0. 01703 mol CH3COOH/0. 0020 L soln. = 0. 8515 M CH3COOH Calculate the percent by mass of acetic acid in vinegar 0. 0020 L CH3COOH x 0. 8515/1 L soln. = 0. 001703 mol CH3COOH 0. 001703 mol CH3COOH x (60. 06g CH3COOH/1 mol CH3COOH) = 0. 1023g CH3COOH 2. 0 mL CH3COOH x (1g CH3COOH/1 mol CH3COOH) = 2. 0 mL CH3CO OH soln. Equation 2 of CH3COOH = (0. 1023 g CH3COOH/2. 0g CH3COOH) x 100% = 5. 115% Final Answer Molarity of vinegar0. 8515 M CH3COOH Percent mass5. 115% CH3COOH From the plots determine the volume of NaOH required to neutralize the KHP solution in each titration.