<p> Thermochemistry Review Questions (Chemistry 30) </p><p>1. How much heat is required to raise the temperature of 7.35g of water from 21.0°C to 98.0°C? </p><p>2. How much heat in kJ is required to raise the temperature of 8.00 ounces of water (237g) from 4.0°C to body temperature? </p><p>3. How much heat in kJ is required to raise the temperature of 2.50g Hg(l) from -2.00°C to 6.00°C. Assume the density of Hg is 13.6g/mL and a molar heat capacity of 28.0J/mol°C.</p><p>4. When 1.0kg of lead (specific heat capacity 0.160J/g°C) at 100.0°C is added to a quantity of water at 28.5°C, the final temperature of the lead water mixture is 35.2°C. What is the mass of water present? </p><p>5. A 1.00g copper sample at 100.0°C is added to 50.0g water at 26.5°C. What is the final temperature of the copper water mixture?</p><p>6. Vanillin is a natural constituent of vanilla. It is also manufactured for use in artificial vanilla flavoring. The </p><p> combustion of 1.013g of vanillin C8H8O3 in a calorimeter causes 1.17kg of water to heat from 24.89°C to 30.09°C. What is the molar heat of combustion of vanillin?</p><p>7. The combustion of a 1.176g sample of benzoic acid causes a temperature increase of 4.96°C in a calorimeter containing 1000g of an unknown liquid (not aqueous solution). The heat of combustion of benzoic acid is -3226kJ/mol. Determine the heat capacity of the liquid in the calorimeter. </p><p>8. Two solutions, 100.0mL of 1.00mol/L AgNO3(aq) and 100.0mL of 1.00mol/L NaCl(aq) both initially 22.4°C are added to a Styrofoam cup calorimeter and allowed to react. The temperature rises to 30.2°C. Determine the molar enthalpy of the reaction. </p><p>9. Two solutions, 100.0mL of 1.020mol/L HCl and 50.0mL of 1.988mol/L NaOH, both initially 24.52°C are mixed in a Styrofoam cup calorimeter. Determine the molar enthalpy of neutralization if the final temperature of the mixture is 33.69°C.</p><p>10. What mass of sucrose must be burned to produce 1.00x103kJ of heat?</p><p>11. A 25.0mL sample of 0.1045mol/L HCl(g) was neutralized by NaOH(aq). Determine the heat evolved in this neutralization reaction (assume solid and liquid products are only produced)</p><p>12. The enthalpy of formation for the amino acid leucine C6H13O2N(s) is -637.3kJ/mol. Write the chemical equation to which this value applies. Using this, determine your chemical reaction using only whole number coefficients. </p><p>13. Calculate the heat of combustion per mole of a gaseous fuel that contains C3H8(g) and C4H10(g). </p><p>14. Determine the heat of formation of benzene for the following reaction: 3 2C6H6(l) + 15O2(g)  12CO2(g) + 6H2O(l) ΔH = -6.535x10 kJ</p><p>15. What is the enthalpy change for the reaction of magnesium chloride and sodium hydroxide? </p><p>16. Use Hess’s law to determine ΔH for the reaction C3H4(g) + 2H2(g)  C3H8(g) given that</p><p>H2(g) + ½ O2(g)  H2O(l) </p><p>C3H4(g) + 4O2(g)  3CO3(g) + 2H2O(l) ΔH = -1937kJ</p><p>C3H8(l) + 5O2(g)  3CO3(g) + 4H2O(l) ΔH = -2219.1kJ Electrochemistry Review Questions (Chemistry 30) </p><p>1. Write the net equation for the redox reaction that occurs in a Scandium Silver voltaic cell (assuming the Scandium Electrode Potential to be -2.02V)</p><p>2. Draw a silver aluminum voltaic cell. Label the cathode, anode and all other features of the cell. Write the relevant equations under your cell and calculate the cell potential. </p><p>3. What is the cell potential for the reaction of FeCl2(aq) with Cl2(g) </p><p>4. Predict the products when Pt electrodes are used in the electrolysis of KI(aq) </p><p>5. In the electrolysis of AgNO3(aq) what are the expected products if the anode is silver and the cathode is platinum?</p><p>6. If 12.3g of Cu is deposited at the cathode of an electrolytic cell after 5.50h what was the current used?</p><p>7. For how long would the electrolysis of copper sulfate have to be carried out using Pt electrodes and a current of 2.13A to produce 2.62L of oxygen gas at 26.2°C and 738mmHg pressure at the anode? (R = 8.314LkPa/molK = 62.364LmmHg/molK) </p><p>8. Write the half reactions and the net equation for the following reaction. Label the oxidizing agent / reducing agent, reduction and oxidation half reactions, and calculate the cell potential. Finally, determine whether the reaction is spontaneous or non-spontaneous. </p><p> a. CuSO4(aq) + Fe(s) </p><p> b. NaBr + Cl2(g) </p><p> c. NaCl + Br2(g) </p><p> d. Fe2(SO4)3(aq) + Al</p><p>9. Compare and contrast corrosion of iron caused under atmospheric conditions, compared with corrosion under acid rain conditions. Use half reactions in your discussion and list 3 chemical solutions to the problem of corrosion Thermochemistry Review KEY</p><p>1. Q = 2.371kJ 2. Q = 32.77kJ 3. omit…. This question is too in depth for chem 30 (sorry!) 4. m = 369.32g 5. tf = 26.6348°C</p><p>6. ΔHm = -3829.0786kJ/mol 7. c = 6.26kJ/kg°C</p><p>8. ΔHm = -6.5364kJ/mol</p><p>9. ΔHm = -57.98kJ/mol 10. m = 66.4g sucrose</p><p>11. ΔH = Q = 0.275kJ </p><p>12. 6C + 13/2H2 + 1O2 + 1/2N2  C6H13O2N + 637.3kJ</p><p>13. ΔHcombustion C3H8 = -2043.9kJ/mol, ΔHcombustion C4H10 = -2657.3kJ/mol</p><p>14. ΔHmf = 49.1kJ/mol 15. ΔHrxn = -254kJ 16. ΔHrxn =-289.5kJ Electrochemistry Review KEY 1. 3Ag+(aq) + Sc(s)  3Ag(s) + Sc3+(aq) 2. Anode – Oxidation Al(s)  Al3+(aq) + 3e- Cathode + Reduction Ag1+(aq) + 1e-  Ag(s)</p><p>3. E°cell = 0.59V</p><p>4.  I2(g) + H2(g) + 2OH-(aq) 5.  Silver will plate the platinum electrode 6. I = 1.886A 7. t = 5.214hours 8. a. Fe(s) + Cu2+(aq)  Fe2+(aq) + Cu(s) = SPONTANEOUS E°cell = 0.79V</p><p>1- 1- b. Cl2(g) + 2Br (aq)  2Cl (aq) + Br2(g) = SPOTANEOUS E°cell = 0.29V</p><p>1- 1- c. 2Cl (aq) + Br2(g)  Cl2(g) + 2Br (aq) = NONSPONT E°cell = -0.29V d. 3Fe3+(aq) + 1Al(s)  3Fe2+(aq) + 1Al3+(aq) = SPONTANEOUS E°cell = 2.43V</p><p>2+ 9. 2Fe(s) + 2H2O(l) + O2(g)  2Fe (aq) + 4OH-(aq) regular rusting</p><p>2+ 2Fe(s) + O2(g) + 4H+(aq)  2Fe (aq) + 2H2O(l) acid rusting increases spont Sacrificial Anode – oxidizes instead of the metal (Fe) bc it’s a stronger RA Galvanization – coats the metal so nothing can get at it AND is a stronger RA Painting – coats metal so water, oxygen and acid cannot reach metal Alloys – mixing a metal with another (i.e. stainless steel) </p>