CHEZ 302 Second Test November 23, 2015 For each of the following questions, mark
ID: 974200 • Letter: C
Question
CHEZ 302 Second Test November 23, 2015 For each of the following questions, mark the correct answer on the answer sheet. Each correct answer is worth 4 (four) points. Molar masses: Carbon 12.01 g/mol Hydrogen- 1.01 g/mol Nitrogen 14.01 g/mol Oxygen 16.00 g/mol I. What is the mass percent of carbon in a compound which has a molecular formula of CaH:0? a. 85.6% b. 92.2% 71.9 % 60.00 % OH 2. What is the empirical formula of A TLC (silica gel, ethyl acetate) was run on the crude product from the electrophilic aromatic substitution reaction, the recrystallized product, and the filtrate from the recrystallization: 3. A crude product B recrystalliz ed product C fitrate from recrystalization experimentai mp of recrystalized product 203-205 c it mp o-nitroacetanilide 94C mp p- acetanide s 214-217°C ABC Which compound is less polar? a. o-nitroacetanilide b. p-nitroacetanilide c. they both have the same polarityExplanation / Answer
Question 1 You need to multiply the molecular weight of the carbon by the number of carbons atoms. The result is 71.99 % Question 2 The empirical formula is C8H8O2, when you count the elements, you need to take atention to the double bounds and Hydrogens present. Question 3 The o-nitroacetanilide is less polar because the interation of the oxigen and the hydrogen is more strong (Hydrogen bridge) than with the solvent.