January 2012 Chemistry Regents #75-78

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50 Questions 51-54 Questions 55-57 Questions 58-59 Questions 60-62 Questions 63-65 Questions 66-69  Questions 70-71  Questions 72-74 Questions 75-78  Questions 79-81  Questions 82-85

Question

Base your answers to questions 75 through 78 on the information below.   Vitamin C, also known as ascorbic acid, is water soluble and cannot be produced by the human body. Each day, a person's diet should include a source of vitamin C, such as orange juice. Ascorbic acid has a molecular formula of C6H8O6 and a gram-formula mass of 176 grams per mole. 75 What is the color of the indicator thymol blue after it is added to an aqueous solution of vitamin C? [1] HIGHLIGHT TO SEE THE ANSWER Yellow 76 Determine the number of moles of vitamin C in an orange that contains 0.071 gram of vitamin C. [1] HIGHLIGHT TO SEE THE ANSWER 0.000 40mol 4.0 x 10-4 mol 77 In the space in your answer booklet, show a numerical setup for calculating the percent composition by mass of oxygen in ascorbic acid. [1] link TO SEE THE ANSWER 78 Write the empirical formula for ascorbic acid. [1] HIGHLIGHT TO SEE THE ANSWER C3H4O3   on to Questions 79-81

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