Explain the difference in the bond dissociation energies for the following bonds: ( C — F , 45 0 kJ/mol ) , ( C — Cl , 33 0 kJ/mol ) , ( C — Br , 270 kJ/mol ) , ( C — I , 240 kJ/mol ) .
Explain the difference in the bond dissociation energies for the following bonds: ( C — F , 45 0 kJ/mol ) , ( C — Cl , 33 0 kJ/mol ) , ( C — Br , 270 kJ/mol ) , ( C — I , 240 kJ/mol ) .
Solution Summary: The author explains the differences in the bond dissociation energies for the given chemical bonds.
Explain the difference in the bond dissociation energies for the following bonds:
(
C
—
F
,
45
0
kJ/mol
)
,
(
C
—
Cl
,
33
0
kJ/mol
)
,
(
C
—
Br
,
270
kJ/mol
)
,
(
C
—
I
,
240 kJ/mol
)
.
Formula Formula Bond dissociation energy (BDE) is the energy required to break a bond, making it an endothermic process. BDE is calculated for a particular bond and therefore consists of fragments such as radicals since it undergoes homolytic bond cleavage. For the homolysis of a X-Y molecule, the energy of bond dissociation is calculated as the difference in the total enthalpy of formation for the reactants and products. X-Y → X + Y BDE = Δ H f X + Δ H f Y – Δ H f X-Y where, ΔHf is the heat of formation.
Acetylene gas (HC≡CH) burns in an oxygen (O2) rich torch to produce carbon dioxide and water vapor. The enthalpy of reaction for the combustion of acetylene is 1259 kJ/mol. Please use this information to solve Parts A,B,C,D.
A) Calculate the C≡C bond energy.C-H: 413 kJ/mol
O-O: 498 kJ/mol
C-O: 799 kJ/mol
O-H: 467 kJ/mol
B) When 500.0 g of acetylene burns, how many kilojoules of heat are given off?
C) How many grams of CO2 form?
D) How many liters of O2 at 298 K and 18.0 atm are consumed?
PV=nRT & R=0.0821 (L*atm)/(mol*K)
Use the bond energies to estimate the enthalpy change, AH°, for the reaction
H
H
H H
H -C -C -H (g)
Cl- CI (g)
H - C1(g)
H H
Average bond energies, kJ/mol :
С —н 414
а—а 243
С —а 339
Н— а 431
Is this system endothermic or exothermic, and why? *
H2 + CO2 CH202
Reactant bond energies: H-H is 432 kJ/mol, C=O is 799 kJ/mol
Product bond energies: C-H is 413 kJ/mol, C=0 is 745 kJ/mol, C-O is 358 kJ/mol, O-H is 467 kJ/mol
It is exothermic because more energy is given off by the products versus the amount
needed to break up the reactants.
It is exothermic because more energy is needed to break up the reactants versus the
amount given off by the products.
It is endothermic because more energy is needed to break up the reactants versus the
amount given off by the products.
It is endothermic because more energy is given off by the products versus the amount
needed to break up the reactants.
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