Free Printable AP 6.7 Bond Enthalpy

1.

The reaction represented goes essentially to completion. The reaction takes place in a rigid, insulated vessel that is initially at 600 K

Which of the following statements about the bonds in the reactants and products is most accurate?

a)

The sum of the bond enthalpies of the bonds in the reactant is greater than the sum of the bond enthalpies of the bonds in the products.

b)

The sum of the bond enthalpies of the bonds in the reactant is less than the sum of the bond enthalpies of the bonds in the products.

c)

The length of the bond between carbon and oxygen in CH₃OH is shorter than the length of the bond between carbon and oxygen in CO.

d)

All of the bonds in the reactant and products are polar.

2.

Which of the following statements must be true for the combustion of CH4(g), represented by the equation? $CH_4(g)+2\ O_2(g)→CO_2(g)+2\ H_2O(g)\ \ \ \ \ \ \ \ \ \ \ \ ΔH°<0$

a)

The bond dissociation energy between O atoms in O2 is greater than the sum of the bond dissociation energies of the two O−H bonds in H2O.

b)

More bonds are formed in the products than are broken in the reactants.

c)

The sum of the bond dissociation energies of the product molecules is EQUAL to the sum of the bond dissociation energies of the reactant molecules.

d)

The sum of the bond dissociation energies of the product molecules is GREATER than the sum of the bond dissociation energies of the reactant molecules.

3.

CO(g) + 2 H₂(g) ⇄ CH₃OH(g) ΔH < 0

The synthesis of CH₃OH(g) from CO(g) and H₂(g) is represented by the equation above. The value of K_c for the reaction at 483 K is 14.5.

Which of the following statements is true about bond energies in this reaction?

a)

The energy absorbed as the bonds in the reactants are broken is greater than the energy released as the bonds in the product are formed.

b)

The energy released as the bonds in the reactants are broken is greater than the energy absorbed as the bonds in the product are formed.

c)

The energy absorbed as the bonds in the reactants are broken is less than the energy released as the bonds in the product are formed.

d)

The energy released as the bonds in the reactants are broken is less than the energy absorbed as the bonds in the product are formed.

4.

The oxidation of carbon monoxide can be represented by the chemical equation $2CO(g)+O_2(g)→2CO_2(g)$ . The table above provides the average bond enthalpies for different bond types. Based on the information in the table, which of the following mathematical expressions is correct for the estimated enthalpy change for the reaction?

a)

$ΔHrxn=[2(1072\ \frac{kJ}{mol})+(498\ \frac{kJ}{mol})]−2(799\ \frac{kJ}{mol})$

b)

$ΔHrxn=[2(1072\ \frac{kJ}{mol})+(498\ \frac{kJ}{mol})]−4(799\ \frac{kJ}{mol})$

c)

$ΔHrxn=[2(799\frac{kJ}{mol})+(142\frac{kJ}{mol})]−4(360\frac{kJ}{mol})$

d)

$ΔHrxn=[2(799\frac{kJ}{mol})+(142\frac{kJ}{mol})]−2(360\frac{kJ}{mol})$

5.

Shown above are the equation representing the decomposition of H2O2(l) and a table of bond enthalpies. On the basis of the information, which of the following is the enthalpy of decomposition of 2 mol of H2O2(l) ?

a)

−349kJ

b)

−203kJ

c)

203kJ

d)

349kJ

6.

An equation representing the dissociation of O2(g) and a table of bond enthalpies are shown above. Based on the information, which of the following is the enthalpy of dissociation for O2(g)?

a)

−641kJ/mol

b)

−495kJ/mol

c)

495kJ/mol

d)

641kJ/mol

7.

CH₄(g) + Cl(g) → CH₃(g) + HCl(g) ΔH° = -14 kJ/mol_rxn

NH₃(g) + Cl(g) → NH₂(g) + HCl(g) ΔH° = -36 kJ/mol_rxn

H₂O(g) + Cl(g) → OH(g) + HCl(g) ΔH° = + 40 kJ/mol_rxn

Based on the data above, what can be concluded regarding the strength of the C-H, N-H, and O-H bonds in the molecules shown?

a)

The C-H bond is the strongest.

b)

The N-H bond is the strongest.

c)

The O-H bond is the strongest.

d)

Nothing can be concluded without knowing the strength of the H- Cl bond.

8.

A mixture of NO₂(g) and N₂O₄(g) is placed in a glass tube and allowed to reach equilibrium at 70°C, as represented above.

Which of the following statements about ∆H° for the reaction is correct?

a)

ΔH° < 0 because energy is released when the N−N bond breaks.

b)

ΔH° < 0 because energy is required to break the N−N bond.

c)

ΔH° > 0 because energy is released when the N−N bond breaks.

d)

ΔH° > 0 because energy is required to break the N−N bond.

9.

Based on the bond energies shown in the table above, which of the following diagrams best represents the change in energy as the reaction represented below proceeds?

H₂(g)+ Cl₂(g)→2HCl(g)

a)

b)

c)

d)

10.

_____ Hydrogen-Hydrogen single bond/s are broken and _____ Carbon-Hydrogen single bond/s formed

a)

6; 8

b)

2; 8

c)

2; 10

d)

6; 10

11.

_____ Carbon-Carbon single bond/s are formed

a)

6

b)

2

c)

3

d)

10

12.

Bond enthalpy is the amount of energy is takes to break __________ of a bond.

a)

one mole

b)

one gram

c)

the activation energy

d)

the binding energy

13.

Using bond energies to solve for enthalpy,

a)

$\Delta H$ = Bond broken - bonds formed

b)

undefined = Bond formed- bonds broken

c)

undefined = products - reactants

d)

undefined = reactants- products

14.

Some average bond enthalpies, in kJ/mol, are as follows:
H-H = 436
Cl-Cl = 242
H-Cl = 431
What is the enthalpy change for the decomposition of hydrogen chloride?
2 HCl --> H₂ + Cl₂

a)

-184 kJ

b)

+ 184 kJ

c)

- 247 kJ

d)

+ 247 kJ

15.

The average bond enthalpies for O-O and O=O are 146kJ/mol and 496kJ/mol respectively. Calculate the enthalpy change for the reaction shown.

a)

-102kJ

b)

+102kJ

c)

+146kJ

d)

-248 kJ

16.

Breaking bonds is _________________. Forming bonds is ______________________

a)

endothermic, exothermic

b)

exothermic, endothermic

17.

Using the table of average bond energies below the image, the ΔH for the reaction in kJ is.....

a)

+ 160 kJ

b)

-63 kJ

c)

- 160 kJ

d)

-217 kJ

18.

Using the reaction & table above, determine the change in energy and whether or not the reaction is endothermic or exothermic:

a)

-2054 kJ endothermic

b)

2023 kJ endothermic

c)

-2023 kJ exothermic

d)

2023 kJ exothermic

19.

Use the bond energy data below to find the ΔH for

2H₂O(g) ⟶ 2H₂(g) + O₂(g)

a)

+480 kJ

b)

-480 kJ

c)

-440 kJ

d)

+ 440 kJ

20.

An equation representing the dissociation of O₂(g) into two oxygen atoms, and a table of bond enthalpies are shown above. Based on the information, which of the following is the enthalpy of dissociation for O₂(g)?

a)

−641kJ/mol

b)

−495kJ/mol

c)

495kJ/mol

d)

641kJ/mol

AP 6.7 Bond Enthalpy

Total questions: 20

Worksheet time: 28mins

Similar Resources on Wayground