Question 1

Which statement best describes the relationship between bond order and bond length?

Accepted Answer

As bond order increases, bond length decreases.

Question 2

What is the bond order of the N—O bond in $$NO_2$$^-$$, given its resonance structures?

Accepted Answer

$$1.5$$

Question 3

Which of the following bonds has the shortest bond length?

Accepted Answer

H—F

Question 4

Given the following bond energies: H—H $$= 436 kJ/$$mol, Cl—Cl $$= 242 kJ/$$mol, H—Cl $$= 432 kJ/$$mol, what is the enthalpy change $$\Delta H_{rxn}$$ for the reaction $$H_2(g$$) + $$Cl_2(g$$) \rightarrow 2HCl(g)$$?

Accepted Answer

$$-174 kJ$$

Question 5

Which bond has the highest bond energy according to the provided data?

Accepted Answer

N≡N

Question 6

What is the main reason fractional bond orders occur in molecules?

Accepted Answer

Resonance structures

Question 7

Which of the following statements is true regarding bond energy and bond order?

Accepted Answer

Bond energy increases as bond order increases.

Question 8

Estimate the $$\Delta H$$ for the reaction $$CH_4(g) + 2O_2(g$$) \rightarrow $$CO_2(g) + 2H_2O(l$$)$$ using the following bond energies: C—H = 413$ kJ/mol, O=O = 495$ kJ/mol, C=O = 745$ kJ/mol, O—H = 463$ kJ/mol.

Accepted Answer

$$-694 kJ/$$mol

Question 9

Which factor does NOT affect bond length?

Accepted Answer

Bond energy

Question 10

Based on the following data, what is the Br—Br bond energy? $$H_2(g$$) + $$Br_2(g$$) \rightarrow 2HBr(g); \Delta H = -36.44$$ kJ. Bond Energies: H—H = 435$ kJ/mol; H—Br = 362$ kJ/mol.

Accepted Answer

399 kJ/mol

Question 11

Which of the following best explains why the bond length of H—I is longer than that of H—F?

Accepted Answer

Iodine is larger than fluorine.

Question 12

If a molecule has a bond order of 3, what can you infer about its bond energy and bond length compared to a bond order of 1?

Accepted Answer

Higher bond energy and shorter bond length.

Question 13

Which of the following is the correct definition of bond energy?

Accepted Answer

The energy required to break a bond.

Question 14

Which molecule would you expect to have the shortest C—O bond length?

Accepted Answer

CO

Question 15

A student claims that the bond order of a single bond is always 2. Is this correct?

Accepted Answer

No, because single bonds have a bond order of 1.

Question 16

Which of the following is a consequence of resonance in molecules like $$NO_2$$^-$$?

Accepted Answer

Bond order becomes fractional.

Question 17

If the bond energy of C≡C is $$835 kJ/$$mol and C=C is $$602 kJ/$$mol, what does this indicate about the relative strength of these bonds?

Accepted Answer

C≡C is stronger than C=C.

Question 18

Which of the following is true about the bond length of C—Cl compared to C—Br?

Accepted Answer

C—Br is longer than C—Cl.

Question 19

Which of the following best describes the method for estimating reaction enthalpy using bond energies?

Accepted Answer

Sum the energies of bonds broken and subtract the energies of bonds formed.

Bond Order, Bond Length, and Bond Energy: Concepts and Calculations

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