Exercise 5 Page 5 Illinois Central College CHEMISTRY 130 Laboratory Section: Name: PRELAB: Exp. 5 Chemical Stoichiometry: The Determination of Vitamin C. SHOW YOUR WORK 1. A 0.258 g sample of a powder containing some ascorbic acid required 14.50 mL of 0.100 M NaOH for complete neutralization. Calculate the purity of the ascorbic acid. moles of NaOH used in the titration moles of ascorbic acid reacted grams of ascorbic acid in sample Percent purity of the powder 2 A tablet of Vitamin C weighed 0.306 g and required 15.70 mL of 0.0300 M KIO, solution for oxidation to the blue starch-iodine endpoint. Calculate the percent ascorbic acid in the tablet. moles of KIO, used in the titration moles of ascorbic acid reacted grams of ascorbic acid in tablet Percent ascorbic acid in tablet

3 attempts left Check my work Be sure to answer all parts. Solid NaBr is slowly added to a solution that is 0.074 M in Cut and 0.074 M in Agt. Which compound will begin to precipitate first? CuBr AgBr What percent of Ag remains in solution at the point when CuBr just begins to precipitate?

Answers: g CE Analysis of NH3 A 0.2502 g sample of the unknown chromium compound was dissolved in water, and 42.56 mL of 0.1089 M HCl was added, converting all the NH3 to NH4 with HCI left over. The excess HCI was titrated with 0.1022 M NaOH, requiring 10.28 mL Moles HCl added moles Moles NaOH added moles Moles HCI USED moles moles Moles NH3 Grams NH3 grams % % NH3

Please correct answer and don't use hand rating

Question 8 Statement 1: Mohr titration is usually performed in an acidic medium. Statement 2: This is because under acidic conditions, the chromate ion is protonated to form chromic acid which leads to immediate precipitation at the end O Statement 1 is incorrect and Statement 2 is correct O Both statements are incorrect O Statement 1 is correct and Statement 2 is incorrect O Both statements are correct point.

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