Grossmont College Chemistry 141 Exam 1 Spring 2016 Name Date Instructor Diana Vance Exam 1 Part 1 Multiple Choice 2 points each Directions Please circle the best answer for each of the following questions 1 Which of the following represent a valid hypothesis a Metals tend to lose electrons b Neon does not react with oxygen gas c Sodium metal reacts violently with water d Lead is soft and malleable e all of the above 2 3 The boiling point of neon is 27 K or a 401 F b 105 F c 246 C d 300 C e none of the above 4 5 6 Which of the following contains the most atoms a 10 0 g Ne b 10 0 g He c 10 0g Ar d 10 0 g Mg e none of the above What species is represented by the following information p 12 n0 14 e 10 a Si4 b Mg c Ne d Mg2 e none of the above Answer the following questions about 7 What is the coefficient of water a 1 b 2 c 3 d 4 e 6 Al2S3 s H2O l Al OH 3 s H2S g 8 Which classification best describes the reaction a Synthesis reaction b Oxidation Reduction reaction c Double replacement reaction d Decomposition reaction e Combustion reaction 9 Determine the theoretical yield of H2S if 4 0 mol Al2S3 and 4 0 mol H2O are reacted a 12 mol H2S b 4 0 mol H2S c 18 mol H2S Page 1 of 7 Grossmont College Chemistry 141 Exam 1 Spring 2016 Name Date Instructor Diana Vance d e 2 0 mol H2S none of the above 10 John Dalton postulated that all matter is composed of small particles called atoms For this proposition to be considered a valid scientific theory a it must be supported by experimental evidence and testing b it must be impossible to prove wrong by experiment c all possible experiments must never find an exception to it d some but only a few experiments may find exceptions to it e it must be voted on by the scientific community and accepted by all 11 In the copper experiment what color was the copper II sulfate solution produced in step 4 a Red b Purple c Blue d Colorless e Clear 12 What element appeared on your first graded lab report a Hydrogen b Oxygen c Tungsten d Iron e Sodium 13 Page 2 of 7 Grossmont College Chemistry 141 Exam 1 Spring 2016 Name Date Instructor Diana Vance 14 Part 2 Short Answer 15 Directions Answer each of the following questions Be sure to use complete sentences where appropriate For full credit be sure to show all of your work 1 List three reasons why the actual yield for a chemical reaction may differ from the theoretical yield 4 points 16 17 1 The reactants and products reach an equilibrium situation where not all the reactants are consumed but are in equilibrium with the products 2 The reaction is very slow and not enough time was allowed for all the reactants to be converted to products 3 Some of the product was lost through careless processing which lowers the yield 4 Some impurities were included with the product which appears to increase the yield 5 Other reactions side reactions consumed some of the reactants 18 2 Yeast converts glucose into ethanol and carbon dioxide in a process called fermentation The unbalanced reaction equation is given below The reaction if 150 0 g of glucose yields 75 0 mL of ethanol d 0 789 g mL 12 points 19 C6H12O6 aq C2H5OH aq CO2 g a Write the balanced equation 20 C6H12O6 aq 2 C2H5OH aq 2 CO2 g b What is the theoretical yield of ethanol in grams 21 150 0 g C 6 H 12 O6 1mol C 6 H 12 O6 2 mol C 2 H 5 OH 46 019 g C 2 H 5 OH 76 71 518018 g 180 156 g C6 H 12 O6 1mol C 6 H 12 O6 1 mol C2 H 5 OH c What is the actual yield of ethanol in grams 0 789 g 59 175 g 22 75 0 mL 1 mL d What is the percent yield for the reaction 59 1 75 g 100 77 13597213 77 1 23 percent yield 76 71 518018 g 24 3 Fill in the missing information in the following table 8 points 25 Symbol 26 137 56 30 Number Protons 35 Number Neutrons 40 Number Electrons Ba of 31 56 2 of 36 13756 81 of 41 56 2 54 27 2 32 16 S 28 98 42 Mo 29 238 92 U 32 32 16 16 33 42 34 92 37 16 38 56 39 238 92 146 42 18 43 42 44 92 Page 3 of 7 Grossmont College Chemistry 141 Exam 1 Spring 2016 Name Date Instructor Diana Vance 45 Mass Number 46 137 47 32 48 42 56 98 49 238 50 51 4 In the movie The Italian Job thieves steal gold bullion One plan was to carry the ingots of gold off in suitcases Each suitcase was 19 inches 14 inches 10 inches 6 points a What is the volume of a suitcase in mL 52 V l w h 19 14 10 53 1 2 54 cm V 54 V 4 358959024 104 mL 4 4 10 4 mL b Approximately how much would each suitcase weigh when filled with gold The density of gold is 19 3 g mL 19 3 g 4 841279 0916 g 8 4 105 g 840 kg 55 4 4 10 mL 1 mL 5 Phthalocyanine is a large molecule used in printing inks and dyes for clothing due to its insolubility in most solvents its chemical stability and its intense blue color Elemental analysis showed that it consists of 74 69 C 3 525 H and 21 77 N 10 points a What is the empirical formula for phthalocyanine 1 mol C 6 218466406 mol C 56 74 69 C 74 69 g C 12 011 g C 1mol H 3 49702381mol H 57 3 525 H 3 525 g H 1 008 g H 1 mol N 1 554222889mol N 58 21 77 N 21 77 g N 14 007 g N 59 C 6 218466406 H 3 49702381 N 1 554222889 1 554222889 1 554222889 1 554222889 60 C 4 001013273 H 2 250015223 N 4 61 C16 00405309 H 9 000060892 N 4 C 16 H 9 N 4 62 b If phtahlocyanine has a molar mass of 514 54 g mol what is the molecular formula for phthalocyanine Page 4 of 7 Grossmont College Chemistry 141 Exam 1 Spring 2016 Name Date Instructor Diana Vance g molar mass mol 1 999953357 2 63 ratio empirical mass 257 276 g mol 64 molecular formu la C16 H 9 N 4 2 C 32 H 18 N 8 65 514 54 6 Correct the following chemical names and write the chemical formula 6 points a Trisodium phosphate sodium phosphate Na3PO4 b Neodymium III chlorine hexahydrate neodymium III …