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SupplementalExam–CHM1311–FProf.SandroGambarotta

Date:February2018 Length:3hours LastName:_______________________FirstName:________________________Student#_______________Seat#

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1. (5 points) Sodium hypochlorite solution, sold as chlorine bleach, is potentially dangerous because of the basicity of ClO−, the active bleaching ingredient. (Assume that d of solution = 1.0 g/mL.) a. What is [OH−] in an aqueous solution that is 6.5% NaClO by mass? What is the pH of the solution? Ka(HClO) = 2.9 x 10-8

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2. (1 point) What is the concentration (mol/L) of a solution formed when 10.0L of ammonia gas at 33C and 96.7kPa dissolves in enough water to give a final volume of 0.750L?

3.(5 points) Calculate the number of atoms of Fe in one molecule of hemoglobin, knowing that iron makes up 0.33% of the mass of hemoglobin and whose molar mass is 6.8 x 104 g/mol

4. (2 points) For the following reaction, K = 0.262 at 1000°C:

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At equilibrium, is 1.22 bar. What is the equilibrium partial pressure of CH4(g)?

5. (4 points) A sample of 0.1595 g of menthol (Molar mass = 156.3) was analyzed in a combustion analyzer and yielded 0.449 g CO2 and 0.184 g of H2O. What is menthol’s molecular formula?

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6. (3 points) Nitrogen dioxide decomposes according to the following reaction, where K = 4.48 × 10−13 at a certain temperature: If 0.75 bar of NO2 is added to a container and allowed to come to equilibrium, what are the equilibrium partial pressures of NO(g) and O2(g)?

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7. (1 point) Calculate the number of oxygen atoms in 38.0 g of oxygen gas.

8. (3 points) Calculate the amount of H2S that can form when 158 g of aluminum sulfide reacts with 131 g of water. Al2S3(s) + H2O(l) à Al(OH)3(aq) + H2S(g) (unbalanced)

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9. (1 point) Chromium oxide reacts with H2S according to the following equation:

Cr2O3(s) + H2S(g) à Cr2S3(s) + H2O (l) (please balance it) To produce 421 g of Cr2S3(s) how many (a) moles and (b) grams of Cr2O3(s) are required?

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10. (2 points) Balance the following redox equation in acidic conditions (use either the semi-equation or the direct method. Whatever you feel more comfortable with):

MnO4- + Cl- à Mn2+ + Cl2

2 x [5 e + 8H+ + MnO4- à Mn2+ + 4H2O]

5 x [2Cl- à Cl2 + 2e] ________________________________________

16H+ + 2MnO4- + 10Cl- à 2Mn2+ + 5Cl2+ 8H2O 11.(3 points)When15.0gofCaF2reactswithexcessofH2SO4,HFgasiscollectedat97.9kPaand25.5C.SolidCaSO4istheotherproductofthereaction.Whattemperatureisrequiredtostorethegasina8.63Lcontainerat1.17bar?

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12. (3 points ) Calculate the mass (g) of calcium nitrate in a milliliter of a solution prepared by diluting 64.0 mL of 0.745 mml/L calcium nitrate to a final volume of 0.100L

13. (5 points) When gaseous F2 and solid I2 are heated to high temperature, I2 sublimes and gaseous IF5 forms. If 46.7 kPa of F2 and 2.50 g of solid I2 are placed into a 2.50 L container at 250K and the container is heated to 550K, what is the final total pressure (bar) and partial pressure of I2 gas?

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14.(3points)UsingequationsfromthelistbelowdetermineDHforthisreaction”

C(s,diamond)àC(s,graphite)

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C(s,diamond)+O2(g)àCO2(g)DH=-395.4kJ/mol2CO2(g)à2CO(g)+O2(g)DH=566.0kJ/molC(s,graphite)+O2(g)àCO2(g)DH=-393.5kJ/mol2CO(g)àC(s,graphite)+CO2(g)DH=-172.5kJ/mol

15. (3 points) A 30.5 g sample of an alloy sample at 93.0 C is placed in 50.0 g of water at 22.0 C (heat capacity of water 4.184 J/g.K) of a calorimeter with heat capacity of 9.2 J/K (mass of the calorimeter is build in the value of the heat capacity). If the final temperature is 31.1 C what is the specific heat capacity of the alloy?

16. (3 points) Phosgene is a toxic gas prepared by the reaction of carbon monoxide with chlorine:

These data were obtained in a kinetics study of its formation:

a. Write the rate law for the formation of phosgene.

b. Calculate the average value of the rate constant.

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17. (1 point) For the following reaction, Ea(fwd) = 125 kJ/mol and Ea(rev) = 85 kJ/mol:

Assuming that the reaction occurs in one step, (a) draw a reaction energy diagram; (b) calculate ΔrH°; (c) sketch a possible transition state.

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18. (3 points) Compound A decomposes according to the following equation:

A sealed 1.00-L container initially contains 1.75 × 10−3 mol of A(g), 1.25 × 10−3 mol of B(g), and 6.50 × 10−4 mol of C(g) at 100°C. At equilibrium, [A] is 2.15 × 10−3 mol/L. Find [B] and [C].

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19. (1 point) What is the pH of a solution 0.75 mol/L of NaF? [Ka(HF) = 6.8 x 10-4]

20. (4 points) A buffer that contains 1.05 mol/L B and 0.750 mol/L BH+ has

a pH of 9.50. What is the pH after 0.0050 mol of HCl is added to 0.500 L of this solution?

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