Using bond energies from the table below, estimate ΔH for the reaction below. The two oxygens in the reactant are each bound to carbon. One of the hydrogens is bound to carbon. HCOOH(g) ↔ H2(g) + CO2(g) Bond Energies, kJ/mol Single Bonds   H C N O S F Cl Br I H 432                 C 411 346               N 386 305 167             O 459 358 201 142           S 363 272 --- --- 286         F 565 485 283 190 284 155       Cl 428 327 313 218 255 249 240     Br 362 285 243 201 217 249 216 190   I 295 213 --- 201 --- 278 208 175 149 Multiple Bonds C=C 602 C=N 615 C=O 799 CºC 835 CºN 887 CºO 1072 N=N 418 N=O 607 S=O (in SO2) 532 NºN 942 O2 494 S=O (in SO3) 469

Show What You Know: Hess's Law Use the following chart to complete the calculations for the combustion reactions between ethanol and propane. Compound Total Bond Energy Oxygen, O2 495 kl/mol Carbon Dioxide, CO2 1598 kJ/mol Water, H,0 926 kl/mol

In a calorimeter, a 1.0 g sample of magnesium is burned to form MgO. In doing so, 25.5 kJ of energy are released. What is the Heat of Combustion in kJ/mol of magnesium? 25.5 0.0392 306.2 1.54 x 1025 620

Calculate the standard enthalpy change (kJ/mol) for the following process given the enthalpies of formation provided below. A + 2 B → 3 C AH¢A = 4 kJ/mol AH;B = 29 kJ/mol AH:C = 92 kJ/mol

3. A 10.0 g sample of pure acetic acid, CH3CO2H, is completely burned. The heat released warms 2.0 L of water from 22.3°C to 39.6°C. a. Assuming that no heat was lost to the calorimeter, what is the molar enthalpy change of the complete combustion of acetic acid? Express your answer in kJ/mol.I b. Will the bonds in the products be longer or shorter than the bonds in the reactant

5. For the chemical reaction below (please note, this is the same as CH4 + Br2 → CH3Br + HBr; the Br2 over the arrow is a reactant. Let me know if you have any questions about this): a. How many non-polar and polar bonds are in the reactants? b. How many non-polar and polar bonds are in the products? c. What is the change in enthalpy (AH) for this reaction (positive or negative)? What is the evidence for your response? d. What is the change in entropy (AS) for this reaction (positive or negative)? What is your evidence for your response? e. Is this reaction exergonic (spontaneous) or endergonic (nonspontaneous)? f. Is the carbon in this reaction being reduced or oxidized? What evidence do you have for your claim? H H-CH- H Br₂ hv H H-C-Br + -Br + HBr H

Consider the reaction below. 3D + 2 Q→ 2 E + 3 J AH = 566.8 kJ How many grams of Q must be used to produce 835.2 kJ of energy? Assume there is excess D. Molar mass: D 68.95 g/mol Q 35.25 g/mol E 78.25 g/mol J 44.26 g/mol

7. Estimate the enthalpy of reaction (in kJ/mol) for the combustion of methane. Be sure to show a lewis structure for each molecule. CH, (g) + 20, (g) ·CO, (g) + H,O (g) Bond Bond Enthalpy (kJ/mol) C-O 351 C=0 799 CEO 1070 O-O 142 O=0 498 C-H 414 O-H 460

Calculate the enthalpy of the reaction below (DHrxn, in kJ) using the bond energies provided.  2H2 (g) + O2 (g) --> 2H2O (g)

26. From the relevant bond energies given below, find the approximate AH ( in kilojoules) for the industrial synthesis of chloroform (CHC3) in a reaction of methane ( CH4) with chlorine gas (Cl2). Is the reaction exothermic or endothermic? (4 CH4 (g) + 3Cl+ (g) — СHC1(g) +3 HсI (9) Bond Dissociation Energies ( Bond Enthalpies) in kJ/mol at 298K for Selected Bonds Bond Bond Energy (kJ/mol) С —Н 410 kJ/mol Cl-Cl 243kJ/mol C-Cl 330kJ/mol H-C1 432 kJ/mol