CH 201 Petrovich PRINT NAME CLEARLY FIRST LAST Wednesday February 15 2023 1 A compound has an empirical formula of C2H3NO2 Test 1 Form A a Calculate the mass of nitrogen in this compound to the nearest 0 01 2 x 12 01 3 x 1 01 1 x 14 01 2 x 16 00 73 06 g mol mass N total mass x 100 1 x 14 01 73 06 x 100 19 176 b If the molecular weight of this compound is 219 12 g mol what is the chemical formula for it mass nitrogen 5 pts 219 12 73 06 3 00 3 x C2H3NO2 C6H9N3O6 Chemical Formula 5 pts 2 Given the following thermodynamic data Calculated H for the following reaction Show the logic of how reactions were added CO2 g C s O2 g H 394 kJ Sr s O2 g SrO s H 592 kJ SrCO3 s SrO s CO2 g H 234 kJ Sr s C s 3 2 O2 g SrCO3 s Sr s O2 g SrO s 592 kJ SrO s CO2 g SrCO3 s 1 x 234 kJ C s O2 g CO2 g 1 x 394 kJ Sr s C s 3 2 O2 g SrCO3 s 1220 kJ H kJ 5 pts 3 Calculate the colligative molarity of a 500 0 mL solution prepared with 1 3768 g calcium chloride CaCl2 s CaCl2 s Ca2 aq 2 Cl aq so i 3 1 3768 g CaCl2 x 1 mol 110 98 g 0 01241 mol CaCl2 M mol L 0 01241 mol 0 5000 L 0 02481 M CaCl2 Mc i x M 0 02481 x 3 0 07743 Mc M 5 pts Page 1 Score 20 4a Write the atomization reaction of AlF3 Include states of matter 3 pts AlF3 g Al g 3F g 4b Use the heats of formation to determine the average Al F bond energy in AlF3 Please include units with your answer H f H f AlF3 g H f Al g H f Al s H f F g H f F2 g kJ mol 1507 338 08 78 99 0 0 AlF3 g Al g 3F g H atom 3 H f F g H f Al g H f AlF3 g H atom 3 x 78 99 338 08 1507 2082 05 kJ H atom bonds broke bonds formed 3 Al F 2082 05 kJ 3 mol Al F bonds 694 kJ mol Al F bond energy DAl F 5 pts 5 A 0 6377 M red dye solution was found to have an absorbance of 0 7650 in a 1 00 cm cell What is the concentration of a solution with an absorbance of 0 8349 in the same cell at the same wavelength A elC A1 C1 A2 C2 C2 C1A2 A1 C2 0 6377 M 0 8349 0 7650 0 6960 M 6 What mass of carbon is in a sample of calcium acetate Ca C2H3O2 2 that contains 1 35 grams of calcium dye M 5 pts 1 35g Ca x 1 mol Ca 40 08 g Ca x 4 mol C 1 mol Ca x 12 01 g C 1 mol C 1 618 g C mass carbon g 5 pts Page 2 Score 18 7 What is OH in a solution prepared by mixing the following solutions 500 mL of 1 2 M NaOH 500 mL x 1 2 M 600 mmol 810 mL of 2 0 M LiOH 810 mL x 2 0 M 1620 mmol 250 mL of 1 5 M KOH 250 mL x 1 5 M 375 mmol 400 mL of water 400 mL x 0 0 M 1960 mL 2595 mmol 2595 mmol 1960 mL 1 32 M gain sig fig when adding 8 a Complete the following reaction table in mmol for 25 00 mL of 0 135 M HCl reacting with 10 pts 25 68 grams of iodine I2 s OH M 5 pts 25 00 mL x 0 135 mmol mL 3 375 mmol HCl 25 68 g I2 x 1 mol 253 8 g 0 10118 mol I2 101 18 mmol I2 2HCl aq I2 s 2HI aq Cl2 g initial final 3 375 3 375 0 101 18 1 688 99 49 0 3 375 3 375 0 1 688 1 688 b What is the theoretical yield of Cl2 g in grams 4 pts 1 688 mmol Cl2 x 70 9 mg mmol 119 68 mg 0 1197 g Cl2 c What concentration of HI aq is formed M mmol mL 3 375 mmol HI 25 00 mL 0 135 M theoretical yield grams 3 pts Page 3 score 25 HI M 3 pts 9 For an aqueous solution with a colligative molality of 2 43 m a Calculate the vapor pressure of the solution at 20 C given that the vapor pressure of pure water at 20 C is 17 5 torr P 2 43 m 2 43 mol solute 1 kg water 1000 g water x 1 mol 18 02 g 55 49 mol water Xwater 55 49 55 49 2 43 0 9580 Psol n XwaterP 0 9580 17 5 torr 16 77 torr b Calculate the boiling point of the resulting solution kf 1 86 C m kb 0 563 C m P torr 6 pts Tb mckb 2 43 m 0 563 C m 1 368 C Tb 100 0 1 368 101 368 C boiling point C 4 pts 10 For the following reaction at 1 atm and 25 0 C 2C2H5OH g H2 g C4H10 g 2H2O l a Using standard heats of formation calculate the enthalpy change H H f C2H5OH g H2 g C4H10 g H2O l kJ mol 235 1 0 124 7 285 83 Hrxn H f C4H10 g 2 H f H2O l 2 H f C2H5OH g Hrxn 124 7 2 285 83 2 235 1 0 H f H2 g Hrxn 226 16 kJ b Calculate the work w ngas 1 3 2 mol w ngasRT 2 mol 8 314 J molK 298 K 4955 J 4 955 kJ H kJ 5 pts c If 25 0 grams of C2H5OH reacts with an excess of hydrogen gas at constant pressure and 298 K calculate the change in energy E The mass of C2H5OH if 46 14 g mol w kJ 5 pts E H w 226 16 4 955 221 21 kJ for 2 mol C2H5OH 25 0 g C2H5OH x 1 mol C2H5OH 46 14 g x 221 21 kJ 2 mol C2H5OH 59 93 kJ Page 4 Score 25 E kJ 5 pts 11a Write the two processes required to change solid water at 0 00 C to liquid warmer water at final temperature Tf Include the phase of the water at C to at C at C to at C 11b If 1 750 kJ of heat are added to 2 7651 grams of 0 00 C solid water ice what will the final temperature of the water be 4 pts 2 7651 g water x 1 mol 18 02 g 0 15345 mol water …