Write your answer in the blank. Only what is written CLEARLY in the blank will be graded!

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1 Name (PRINT clearly) Seat Number Exam 2 (100 points) Chemistry October 24, 2018 On my honor, I have neither given nor received unauthorized aid on this exam. Signed Date Write your answer in the blank. Only what is written CLEARLY in the blank will be graded! 1. (4 points) Because larger objects, including molecules, move more slowly than smaller objects, the ratio of the times for a given amount of He and Ar to effuse from (leak out of) a balloon is calculated to be. 2. (3 points) The letters that designate the orbitals within the subshell n = 5 are. 3. (4 points) A M 2+ ion derived from a metal in the first transition metal series has four electrons in the 3d subshell. This metal is. 4. (3 points) The complete ground state configuration for selenium is. 5. (3 points) Among the following is(are) diamagnetic in the ground state? K F Fe S Si Zn 6. (4 points) A cation that is isoelectronic with krypton is. 7. (3 points) The shorthand electron configuration of cesium (Cs) is. 8. (4 points) Deviations from the ideal gas law are greater at temperatures and pressures. (Fill in the blanks with "high" or "low") 9. (4 points) In the following sets of quantum numbers (listed in order of n, l, m l, m s ) which is unacceptable? [Please underline your choice. Do not circle it.] 3, 1, 0, +½ 3, 0, 0, +½ 3, 3, -2, + ½ 2, 0, 1, -½ 2, 0, 0, +½ 10. (4 points) Draw the shape of an orbital with l = 2. Give the specific letter name and and clearly label the axes for the orbital you draw.

2 11. (10 points) An impure g sample of Bi2(Cr2O7)3 (molar mass, 1066) was completely reacted with 22.5 ml of M K 2 S. What is the percent purity of the Bi2(Cr2O7)3 sample? [You MUST CLEARLY show your work to JUSTIFY all of your calculations. We grade what is ON THE PAPER!] 32 H Cr2O S 2-8 Cr SO H 2 O Page (11 points) A solution is prepared by mixing 0.10 L of 0.15 M NaCl with 0.25 L of a 0.20 M solution of MgCl 2. What volume of a 0.50 M solution of AgNO 3 is needed to precipitate all of the Cl ion as AgCl? Clearly show all work and UNITS in every step! 13. (10 points) A sample of a gas has a mass of g. Its volume is 117 ml at a temperature of 85 C and a pressure of 753 mmhg. Find the molar mass of the gas. Clearly show all work and UNITS in every step!

3 Page (12 points) Carbon monoxide gas reacts with hydrogen gas to form methanol, CH 3 OH (molar mass 32.0). A 2.00 L reaction vessel, initially at 305 K contains carbon monoxide gas at a partial pressure of 247 mmhg and hydrogen gas at a partial pressure of 453 mmhg. Identify the limiting reactant and determine the theoretical yielded of methanol in grams. [You must CLEARLY show HOW you determine the limiting reagent. Without this, it will be assumed you guessed and no credit will be given for your answer, even if it is correct.] CO (g) + 2 H 2 (g) CH 3 OH (g) 15. (10 points) Use the following information to calculate the heat of formation of solid calcium oxide, CaO. Clearly show all work and UNITS in every step! CaO (s) + CO 2 (g) CaCO 3 (s) H = 178 kj 2 Ca (s) + 2 CO 2 (g) + O 2 (g) 2 CaCO 3 (s) H = 1626 kj

4 Page (11 points) Instant cold packs used in first aid kits and by athletes to treat injuries contain ammonium nitrate (molar mass 80.0) and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the endothermic reaction: NH 4 NO 3 (s) NH + 4 (aq) + NO 3 (aq). In order to measure the enthalpy change, H, for this reaction, 1.25 g of NH 4 NO 3 was dissolved in enough water to make a total of 25.0 ml of solution. The initial temperature is 25.8 C and the final temperature after the solid dissolves is 21.9 C. Calculate the enthalpy change, H, for this reaction. [Use 1.0 g/ml for the density of the final solution and 4.18 J/g. C for the specific heat of the solution.]

5 Name (PRINT clearly) Seat Number Exam 2 (100 points) Chemistry October 24, 2018 On my honor, I have neither given nor received unauthorized aid on this exam. Signed Date Write your answer in the blank. Only what is written CLEARLY in the blank will be graded! 1. (4 points) Because larger objects, including molecules, move more slowly than smaller objects, the ratio of the times for a given amount of He and Ar to effuse from (leak out of) a balloon is calculated to be. 2. (3 points) The letters that designate the orbitals within the subshell n = 5 are. 3. (4 points) A M 2+ ion derived from a metal in the first transition metal series has four electrons in the 3d subshell. This metal is. 4. (3 points) The complete ground state configuration for selenium is. 5. (3 points) Among the following is(are) diamagnetic in the ground state? K F Fe S Si Zn 6. (4 points) A cation that is isoelectronic with krypton is. 7. (3 points) The shorthand electron configuration of cesium (Cs) is. 8. (4 points) Deviations from the ideal gas law are greater at temperatures and pressures. (Fill in the blanks with "high" or "low") 9. (4 points) In the following sets of quantum numbers (listed in order of n, l, m l, m s ) which is unacceptable? [Please underline your choice. Do not circle it.] 3, 1, 0, +½ 3, 0, 0, +½ 3, 3, -2, + ½ 2, 0, 1, -½ 2, 0, 0, +½ 10. (4 points) Draw the shape of an orbital with l = 2. Give the specific letter name and and clearly label the axes for the orbital you draw.

6 11. (10 points) An impure g sample of Bi2(Cr2O7)3 (molar mass, 1066) was completely reacted with 22.5 ml of M K 2 S. What is the percent purity of the Bi2(Cr2O7)3 sample. 32 H Cr2O S 2-8 Cr SO H 2 O Page (11 points) A solution is prepared by mixing 0.10 L of 0.15 M NaCl with 0.25 L of a 0.20 M solution of MgCl 2. What volume of a 0.50 M solution of AgNO 3 is needed to precipitate all of the Cl ion as AgCl? 13. (10 points) A sample of a gas has a mass of g. Its volume is 117 ml at a temperature of 85 C and a pressure of 753 mmhg. Find the molar mass of the gas.

7 Page (12 points) Carbon monoxide gas react with hydrogen gas to form methanol, CH 3 OH (molar mass 32.0). A 2.00 L reaction vessel, initially at 305 K contains carbon monoxide gas at a partial pressure of 247 mmhg and hydrogen gas at a partial pressure of 453 mmhg. Identify the limiting reactant and determine the theoretical yielded of methanol in grams. [You must CLEARLY show HOW you determine the limiting reagent. Without this it will be assumed you guessed and no credit will be given for your answer, even if it is correct.] CO (g) + 2 H 2 (g) CH 3 OH (g) 15. (10 points) Use the following information to calculate the heat of formation of solid calcium oxide, CaO. [You MUST CLEARLY show you work to JUSTIFY all of your calculations. We grade what is ON THE PAPER!] CaO (s) + CO 2 (g) CaCO 3 (s) H = 178 kj 2 Ca (s) + 2 CO 2 (g) + O 2 (g) 2 CaCO 3 (s) H = 1626 kj

8 Page (11 points) Instant cold packs used in first aid kits and by athletes to treat injuries contain ammonium nitrate (molar mass 80.0) and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the endothermic reaction: NH 4 NO 3 (s) NH + 4 (aq) + NO 3 (aq) In order to measure the enthalpy change, H, for this reaction, 1.25 g of NH 4 NO 3 was dissolved in enough water to make a total of 25.0 ml of solution The initial temperature is 25.8 C and the final temperature after the solid dissolves is 21.9 C. Calculate the enthalpy change, H, for this reaction. [Use 1.0 g/ml for the density of the final solution and 4.18 J/g. C for the specific heat of the solution.]