My question is on #3 termination of Tartaric Acid Concentration in Wine General

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My question is on #3

termination of Tartaric Acid Concentration in Wine General Chemistry I, CHEM 111AF Experiment 4 V06192018 Determination of Tartaric Acid Concentration in wine Overview Day 1. Port A. Standardize a sodium hydroxide solution using potassium hydrogen phthalate (KHP) Day 2. Complete the post laboratory assignment. Part B. Prepare wine sample and titrate three times using a sodium hydroxide solution. Purpose The purpose of this experiment is to determine the mass percent (equation 4.1) and molarity of tartaric acid (Figure 1) In a wine sample using titration. Mass Percent (n/m) = nnas assenseeuteteler-X100 Introduction Titration is a method used by scientists to determine the concentration of an unknown substance. It involves the stoichiometric ratio of a chemical reaction between a substance of known concentration, with a substance of unknown concentration. In a titration it is important to know the exact concentration of the OH titrant in order to determine the concentration of the analyte accurately. In this experiment a 0.1 M NaOH solution will be standardized using potassium hydrogen phthalate (.. commonly abbreviated, . KHP is a weak acid that reacts with sodium hydroxide in a 1:1 molar ratio. acid, molecular formula - C,HO By titrating a known amount of KHP with an indicator, the concentration of NaOH can be determined to four decimal places. Figure 1. Structure of tartaric Indicators are chemicals that change absorbance as pH changes and can be monitored by a color change. At the equivalence point, enough titrant has been added to completely react with the analyte resulting in a large change in pH of the solution. Upon this large change in pH, the indicator will react with any excess titrant and produce a color change (Figure 2). (pH -8.3-14, pink) (pH 1-8.2, colorless) Figure 2. This reaction depicts the dependence of phenolphthalein (an indicator, CaoHy 0A) color, on pH. When phenolphthalein is pH is above 8.3, a ring is opened and changes the color of the molecule to pink in acidic conditions it is colorless, and when the 37

Explanation / Answer

3.  Part 1 Density of wine sample.

Density is given by Mass/ volume.

Now in wine sample, mass = mass of tartaric acid + mass of water and volume is volume of wine.

Part 2 Protocol

We can know mass of tartaric acid by titrating wine sample with know concernated of NaOH.

Take known volume of tartaric acid ( wine) in conical flask and add 1-2 drops of phenolphthalein and NaOH in burette. Titrate the reaction until you get light pink in conical flask. Note the volume of NaOH used. Now do the calculation.

Molarity of tartaric acid = Molarity of NaOH× volume of NaOH/ volume of tartaric acid.

Mass of tartaric acid = (Molarity of tartaric × Vol of tartaric in ml × molar mass of tartaric acid) / 1000 g

Mass of water = Volume of wine sample × density of water at that temperature.

Part 3 Varification

If we take fix volume of wine sample and weight it. Now division of weight by volume gives density of wine sample.

Take the weight of clean and dry 100 ml standard flask with stopper. Let's say the weight is G1g. Now add Carefully 100 ml of your wine sample in 100 ml standard flask ( upto mark) using pipet of 25 ml. Now again take the weight of standard flask with stopper. Now weight is G2g.

Density of wine sample = ( G2-G1)/100 g/ml

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