Analysis of vinegar by titration pre lab

Experiment #5: Titration of the Acetic Acid in Vinegar Individual Pre-Lab 1. The main goal/purpose of the experiment is (what are you trying to discover in this lab): 2. The hypothesis(es) we seek to test in this experiment is(are) (what is the basis of your experiment) (see chapters on chemical reactions and solution concentration in your text book): 3. The key question the experiment seeks to answer is (what problem are you addressing?): 4. The controls involved in this experiment are (a control is used to minimize the unintended influence of other variables on the same system): 5. The key concept(s) or theory (ies) behind the experiment is(are) (define terms like molarity, neutralization, standard solution, etc.): 6. The important technique(s) used in this experiment is(are) Please describe: 7. The experiment is based on the following assumptions (identify your assumptions and determine if they are justifiable): 8. The data that will be collected in the experiment are (what do you plan to record in your notebook) 9. The potential consequences of the experiment are: 10. The point of view behind the experiment is (make sure it’s scientific). 11. What special safety precautions do you need to be aware of for this experiment? Project: A new vinegar product just hit the market. As a food expert you are asked to analyze this vinegar to make sure it has the right amount of the main ingredient— acetic acid. Normally, vinegar should have about 5% acetic acid. Specifically, you will use a standard solution, NaOH, to titrate this vinegar, and determine the concentration of acetic acid. Background: 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 called a standard solution. Titration is one of these volumetric analysis techniques where a standard solution is added to the unknown (analyte) solution incrementally from a buret till the reaction is complete, at which time the volume of the standard solution is determined from the readings of the buret, and the concentration of the analyte solution is calculated. In this project, the main ingredient in vinegar, acetic acid, CH3COOH, is a weak acid, and is neutralized by NaOH, according to the following equation: CH3COOH+NaOH→CH3COONa+H2O Therefore, at the completion of the reaction, the number of moles of CH3COOH equals the number of moles of NaOH. pH indicators are often used in acid-base titration to visually show the completion of the neutralization, called end point. Note: The standard solution is often put in the buret to titrate the analyte solution, thus it is called titrant. However, sometimes the unknown solution can also be put in the buret. Techniques: Laboratory: measuring mass, measuring volume of liquids with accuracy, preparing solutions Computer: apparatus setup using ChemSketch Special Apparatus and Chemicals: Standard NaOH solution 10 mL Volumetric pipet 50 mL Buret 100 mL Volumetric flask Buret Clamp and stand Phenolphthalein Vinegar NaOH (solid) Accurate measurement of volume For precise measurement of volume, volumetric glassware such as volumetric pipets, volumetric flasks, and burets should be used. Volumetric pipets are for accurate transfer of certain amounts of liquids. Burets are for precise delivery of any volume of liquid in any volume increments, and are suited for titration. Review the lab manual (page 30-32) for correct use of these pieces of equipment. Procedure: In this project you will utilize the two methods of preparing a solution (preparation of solutions refer pg. 19 and 20 of the lab manual). In week one you will be given a NaOH stock solution of 1.00 M and you will dilute it to 0.40 M, 100 mL for use in titration. In week two you will be given solid NaOH in order to prepare a standard NaOH solution of 0.40 M. Develop a procedure that includes: