Wine Chemistry

You are given the task of analyzing a sample of grapes todetermine if a vineyard is ready for harvesting

1a. The concentration of tartaric acid is critical. This can bedetermined by a titration experiment with 0.1M NaOH and a colorIndicator (phenolphthalein. The reaction is as follows:

Tartaric acid + 2 NAOH + colorless -> 2 H0+ 2 Na\" +Tartrate

You have a 0.010L sample of grape juice and after adding 0.018 Lof NaOH solution the color turns pink What is the \"Titratableacidity\" in g/L of tartaric acid in the grape juice sample?

Steps: volume of NaOH solution moles of NaOH > moles oftartaric acid grams of tartaric acid. Then divide grams of tartaricacid by volume (L) of grape solution

1b. Acidity goes down as grapes ripen. If the answer to theprevious problem is less than 7 g/L then the grapes are ready.Based on your answer are they ready?

Sza. The ather important consideration is the concentration ofsugar (which increases as grapes ripen). The appropriate sugarlevel is about 200 g/L What is the molarity of sugar in ripe grapeJuice? (molar mass of sugar is 180 g/mole).

26. Amore commonly used unit in wine-making is Brix 1 brix =10g/Of sugar. It your grape juice sample has a brix reading of 10,is it ready to harvest?