Enthalpy 5. B Based on the energy diagram, which of the following statements is true? + H₂ + H2 7 kJ mol −1 5 kJ mol 1 + H₂ AH-127 kJ mol-1 AH-120 kJ mol −1 AH-115 kJ mol −1 (a) 1-butene is 12 kJ mol¹ more stable than trans-2-butene (b) 1-butene is 12 kJ mol¹ less stable than trans-2-butene (c) 1-butene is 12 kJ mol¹ more stable than cis-2-butene (d) 1-butene is 12 kJ mol¹ less stable than cis-2-butene

The two alternative chair conformations of cis-1-cyano-4-methylcyclohexane differ in their Gibbs free energy. Using the data for ΔG° for monosubstituted cyclohexanes at room temperature (25ºC): Axial → Equatorial Group ΔG° (kJ/mol) Group ΔG° (kJ/mol) C-N triple bond −0.8 NH2 −5.9 Br −2.4 CH3 −7.3 OH −3.9 1,2-gauche +3.8 calculate the absolute value of the difference in the Gibbs free energy between the alternative chair conformations.

The enthalpy for hydrogenation of different isomers of butene is shown in the following figure. Which statement below best interprets this figure? Hy I3D H2 7k mot 5kJ mot + H2 AH-120 kJ mot AH"-127 kJ mot AH-115 kJ mot © GMU 2020 Stability and hydrogenation enthalpies are not correlated. Butene II is less stable than butene I by 7 kJ/mol. O Butene Il is 7 kJ/mol more stable than I and 5 kJ/mol more stable than III. Butene II is 5 kJ/mol less atable than butene IlI. Enthalpy

Which compound is capable of hydrogen bonding with itself? 1-PROPANOL - (71-23-8) - Physical Properties • Chemical Properties • Solubility • Uses/Function • Reactions • Thermochemistry F F C-F - - F н F ннн Н-с-с-с-H ннн All of the above None of the above L -U -L HICI I

Following are heats of combustion per mole for methane, propane, and 2,2,4-trimeth-ylpentane. Each is a major source of energy. On a gram-for-gram basis, which of these hydrocarbons is the best source of heat energy?

From the data in Figure 4-12 and Table 4-1, estimate the percentages of molecules that have their substituents in an axial orientation for the following compounds: (a) Isopropylcyclohexane (b) Fluorocyclohexane (c) Cyclohexanecarbonitrile, C6H11CN

Calculate the enthalpy of formation of propane from:a. Combustion data (ΔHc = –2217 kJ mol–1; ΔHf (CO2) = –393.4 kJ mol–1, ΔHf (H2O) =–285.2 kJ mol–1);b. Bond enthalpies (C–C 348 kJ mol–1; C–H 413 kJ mol–1; H–H 436 kJ mol–1; ΔHvap forcarbon = –717 kJ mol–1).

Calculate AHrxn for the reaction: CH4 (9) +4 Cl(g) → CCl4 (g) + 4 HCl(g) Use the following reactions and given AH´s: C(s) + 2 H₂(g) → CH4 (9) C(s) + 2 Cl₂(g) → CCl4 (9) H₂(g) + Cl₂(g) → 2 HCl(g) AH = -74.4kJ AH = -95.7kJ AH = -92.3 kJ

CH₂ CO₂H N- Br ABCN chlorobenzene CH₂Br CO₂H

Some bond dissociation energies in kJ/mol are listed. 1°, 2°, 3° means primary, secondary,tertiary.1° C-H 423 2° C-H 413 3° C-H 4041° C-CN 509 2° C-CN 506 3° C-CN 493For the hypothetical reaction below, do two things:1) Estimate the enthalpy change ΔH° for the reaction. Show your work in the space below.2) Draw a circle around the molecule with the lower enthalpy.