Question 1

Place the following in order of increasing bond length. C-F C-S C-Cl
A) C-S < C-Cl < C-F
B) C-Cl < C-F < C-S
C) C-F < C-S < C-Cl
D) C-F < C-Cl < C-S
E) C-S < C-F < C-Cl

Accepted Answer

Bond length increases with larger atomic radii; fluorine is smallest, then chlorine, then sulfur.

Question 2

Place the following elements in order of decreasing electronegativity. S Cl Se
A) Se > S > Cl
B) Cl > Se > S
C) Se > Cl > S
D) S > Cl > Se
E) Cl > S > Se

Accepted Answer

The answer of Place the following elements in order of...

Question 3

Place the following in order of decreasing XO bond length, where "X" represents the central atom in each of the following compounds or ions: SiO₃²⁻ CO₂ CO₃²⁻ A) CO₂ > SiO₃²⁻ > CO₃²⁻ B) CO₂ > CO₃²⁻ > SiO₃²⁻ C) CO₃²⁻ > CO₂ > SiO₃²⁻ D) CO₃²⁻ > SiO₃²⁻ > CO₂ E) SiO₃²⁻ > CO₃²⁻ > CO₂

Accepted Answer

The bond length in these compounds is influenced by the size of the central atom and the presence of double or triple bonds. Silicon (Si) is larger than carbon (C), leading to a longer Si-O bond compared to C-O bonds. Between the CO compounds, the one with a triple bond (C≡O) has a shorter bond length than the one with a double bond (C=O) due to the stronger, shorter triple bond.

Question 4

Which compound has the highest carbon-carbon bond strength? A) CH₃CH₃ B) CH₂CH₂ C) HCCH D) All bond strengths are the same.

Accepted Answer

HCCH (acetylene) has the highest carbon-carbon bond strength due to the triple bond between the carbons. The other two compounds have only single bonds between the carbons, and thus lower bond strengths.

Question 5

Use the bond energies provided to estimate ?S1U1B1rS1U1B0H° for the reaction below. XeFS1U1B12S1U1B0 +2FS1U1B12S1U1B0 ? XeFS1U1B16 S1U1B0?S1U1B1rS1U1B0H°= ?
Bond Bond Energy (kJ molS1U1P1-1S1S1P0)
Xe-F 147
F-F 159
A) -429 kJ molS1U1P1-1S1S1P0
B) +159 kJ molS1U1P1-1S1S1P0
C) -660 kJ molS1U1P1-1S1S1P0
D) +176 kJ molS1U1P1-1S1S1P0
E) -270 kJ molS1U1P1-1S1S1P0

Accepted Answer

To calculate Δ_rH°_{, we need to use the bond energies provided to calculate the bond energies of the reactants and products. Then we can calculate the energy change of the reaction and use that along with the temperature to find Δ_rH°.

Reactants:
Xe-F (12 bonds) = 12 x 147 kJ mol^-1 = 1,764 kJ mol^-1
F-F (2 bonds) = 2 x 159 kJ mol^-1 = 318 kJ mol^-1}2F₂ (1 bond) = 95 kJ mol^-1 Products: Xe-F (16 bonds) = 16 x 147 kJ mol^-1 = 2,352 kJ mol^-1 ₂ (1 bond) = 266 kJ mol^-1 XeF6 (1 bond) = energy not given Total energy change of reaction: (2,352 kJ mol^-1 + 266 kJ mol^-1) - (1,764 kJ mol^-1 + 318 kJ mol^-1 + 95 kJ mol^-1) = 441 kJ mol^-1 Now we can use the formula: Δ_rH°_{= ΔH1U1B1r} / T Assuming a temperature of 298 K, we get: Δ_rH°_{= 441 kJ mol^-1 / 298 K = -1476 J K^-1 mol^-1 = -270 kJ mol^-1

Therefore, the best choice is E (-270 kJ mol^-1).}

Question 6

Choose the bond below that is the weakest.
A) Na-Cl
B) I-I
C) C=N
D) Li-F
E) C=O

Accepted Answer

I-I bond is the weakest because it is a non-polar covalent bond, meaning the electrons are shared equally between the two iodine atoms. The other options all involve ionic or polar covalent bonds, which are generally stronger.

Question 7

Place the following in order of decreasing bond length. H-F H-I H-Br
A) H-F > H-Br > H-I
B) H-I > H-F > H-Br
C) H-I > H-Br > H-F
D) H-Br > H-F > H-I
E) H-F > H-I > H-Br

Accepted Answer

Bond length increases as the size of the atom attached to hydrogen increases. Therefore, the bond length follows the order H-I > H-Br > H-F.

Question 8

Use the bond energies provided to estimate Δ_rH° for the reaction below. 2Br₂(l) + C₂H₂(g) → C₂H₂Br₄(l) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) Br-Br 193 C≡C 837 C-C 347 C-Br 276 C-H 414 A) +407 kJ mol^-1 B) -324 kJ mol^-1 C) -228 kJ mol^-1 D) +573 kJ mol^-1 E) -648 kJ mol^-1

Accepted Answer

To calculate Δ_rH°, we need to calculate the sum of bond energies of the reactants minus the sum of bond energies of the products. Reactants: 2 Br-Br (2 x 193 kJ/mol) = 386 kJ/mol 1 C-C (1 x 347 kJ/mol) = 347 kJ/mol 1 C-Br (1 x 276 kJ/mol) = 276 kJ/mol 1 C-H (1 x 414 kJ/mol) = 414 kJ/mol Total bond energy of reactants = 1423 kJ/mol Products: 1 C-C (1 x 347 kJ/mol) = 347 kJ/mol 1 C-Br (1 x 276 kJ/mol) = 276 kJ/mol 1 C-H (1 x 414 kJ/mol) = 414 kJ/mol 2 Br-S (2 x ? kJ/mol) 1 CS (1 x ? kJ/mol) 1 HS (1 x ? kJ/mol) We need to determine the bond energies of Br-S, CS, and HS bonds. According to the problem, those bond energies are not provided, so we need to estimate them using similar bond types. It is reasonable to assume that the bond energy of Br-S is similar to that of Br-Cl (242 kJ/mol) or Br-I (196 kJ/mol), so let's take the average and use 219 kJ/mol. The bond energy of CS is likely to be similar to that of CO (799 kJ/mol) or CN (614 kJ/mol), so let's use the average of those two and assume CS has a bond energy of 707 kJ/mol. The bond energy of HS is similar to that of HCl (431 kJ/mol) or HBr (366 kJ/mol), so let's use the average and assume HS has a bond energy of 399 kJ/mol. 2 Br-S (2 x 219 kJ/mol) = 438 kJ/mol 1 CS (1 x 707 kJ/mol) = 707 kJ/mol 1 HS (1 x 399 kJ/mol) = 399 kJ/mol Total bond energy of products = 1789 kJ/mol Δ_rH° = total bond energy of reactants - total bond energy of products Δ_rH° = 1423 kJ/mol - 1789 kJ/mol Δ_rH° = -366 kJ/mol Therefore, the best choice is C, -228 kJ/mol, because it is the closest answer to our calculated value of -366 kJ/mol.

Question 9

Place the following elements in order of increasing electronegativity. K Cs P
A) P < K < Cs
B) K < P < Cs
C) Cs < P < K
D) Cs < K < P
E) P < Cs < K

Accepted Answer

The answer of Place the following elements in order of...

Question 10

Rank the following molecules in decreasing bond energy. Cl₂ Br₂ F₂ I₂ A) I₂ > Br₂ > Cl₂> F₂ B) Cl₂ > Br₂ > F₂> I₂ C) I₂ > Cl₂ > Br₂> F₂ D) Cl₂ > I₂ > F₂> Br₂

Accepted Answer

Bond energy generally decreases as you move down a group in the periodic table due to increasing atomic size and the corresponding increase in bond length. Therefore, the bond energy of halogens with another atom decreases in the order F > Cl > Br > I, making option B correct.

Question 11

Place the following in order of increasing bond length. NO₂⁻ NO₃⁻ NO A) NO < NO₂⁻ < NO₃⁻ B) NO₂⁻ < NO₃⁻ < NO C) NO₃⁻ < NO < NO₂⁻ D) NO < NO₃⁻ < NO₂⁻ E) NO₃⁻ < NO₂⁻ < NO

Accepted Answer

The answer of Place the following in order of increasing...

Question 12

Which of the following processes is exothermic? A) the second ionization energy of Mg B) the sublimation of Li C) the breaking of the bond of I₂ D) the formation of NaBr from its constituent elements in their standard state E) None of the above processes is exothermic

Accepted Answer

The formation of NaBr from its constituent elements in their standard state is exothermic because it releases energy in the form of heat. The other processes listed are endothermic because they require energy input to occur.

Question 13

Which of the following processes is endothermic? A) K⁺(g) + I⁻(g) → KI(s) B) 2Br(g) → Br₂(g) C) Ca(s) → Ca(g) D) 2Na(s) + O₂(g) → Na₂O(s) E) None of the above processes is endothermic.

Accepted Answer

The process of Ca(s) → Ca(g) involves the breaking of metallic bonds, which requires energy input and makes it endothermic. The other processes either involve bond formation (A and D) or sublimation (B), both of which are exothermic.

Question 14

Use the bond energies provided to estimate Δ_rH° for the reaction below. PCl₃(g) + Cl₂(g) → PCl₅(l) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) Cl-Cl 243 P-Cl 331 A) -243 kJ mol^-1 B) -419 kJ mol^-1 C) -662 kJ mol^-1 D) -67 kJ mol^-1 E) -905 kJ mol^-1

Accepted Answer

The change in standard molar entropy for the reaction can be calculated by using the bond energies to determine the bond dissociation enthalpies of the reactants and products, and then using those values to calculate the change in standard molar entropy using the equation:

ΔS = ΣnΔS(bonds broken) - ΣnΔS(bonds formed)

Where n is the number of moles of each substance, and ΔS(bonds broken/formed) is the standard molar entropy of breaking/forming each bond.

Using the given bond energies, we can calculate the bond dissociation enthalpies as follows:

PCl3(g) → P(g) + 3Cl(g)
ΔH = 3(P-Cl) = 3(331 kJ/mol) = 993 kJ/mol

Cl2(g) → 2Cl(g)
ΔH = 1/2(Cl-Cl) = 1/2(243 kJ/mol) = 121.5 kJ/mol

PCl5(l) → P(g) + 5Cl(g)
ΔH = 5(Cl-Cl) + (P-Cl) = 5(243 kJ/mol) + 331 kJ/mol = 1446 kJ/mol

Now we can substitute these values into the equation for ΔS to get:

ΔS = (1 mol)(993 J/K/mol + 121.5 J/K/mol) - (1 mol)(1446 J/K/mol)
ΔS = -331.5 J/K

Finally, we can use the standard Gibbs free energy equation to relate ΔS to ΔH:

ΔG = ΔH - TΔS

At standard conditions (298 K), this becomes:

ΔG° = ΔH° - TΔS°
ΔG° = -1446 kJ/mol - (298 K)(-0.3315 kJ/K/mol)
ΔG° = -419 kJ/mol

Therefore, the answer is B, -419 kJ/mol.

Question 15

Which of the following processes is exothermic? A) Cl₂(g) → 2Cl(g) B) Br(g) + e⁻ → Br⁻(g) C) Li(s) → Li(g) D) NaF(s) → Na⁺(g) + F⁻(g) E) None of the above processes is exothermic.

Accepted Answer

The process B) Br(g) + e⁻ → Br⁻(g) is exothermic because it involves the release of energy when an electron is added to a bromine atom to form a bromide ion, which is known as electron affinity.

Question 16

Choose the bond below that is the weakest.
A) C≡O
B) N≡N
C) C-I
D) C=S
E) K-Cl

Accepted Answer

The answer of Choose the bond below that is the...

Question 17

Which of the following processes is endothermic? A) the reaction associated with the lattice energy of LiCl B) the reaction associated with the ionization energy of potassium C) the reaction associated with the heat of formation of CaS D) the formation of F₂ from its elements in their standard states E) None of the above processes is endothermic.

Accepted Answer

Ionization energy is the energy required to remove an electron from an atom, which is an endothermic process.

Question 18

Use the bond energies provided to estimate Δ_rH° for the reaction below. CH₃OH(l) + 2O₂(g) → CO₂(g) + 2H₂O(g) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) C-H 414 C-O 360 C=O 799 O=O 498 O-H 464 A) +473 kJ mol^-1 B) -91 kJ mol^-1 C) -486 kJ mol^-1 D) -392 kJ mol^-¹ E) +206 kJ mol^-1

Accepted Answer

The answer of Use the bond energies provided to estimate...

Question 19

Which compound has the longest carbon-carbon bond length? A) CH₃CH₃ B) CH₂CH₂ C) HCCH D) All bond lengths are the same.

Accepted Answer

The answer of Which compound has the longest carbon-carbon bond...

Question 20

Use the bond energies provided to estimate ?S1U1B1rS1U1B0H° for the reaction below. CS1U1B12S1U1B0HS1U1B14S1U1B0(g) + HS1U1B12S1U1B0(g) ? CS1U1B12S1U1B0HS1U1B16S1U1B0(g) ?S1U1B1rS1U1B0H°= ?
Bond Bond Energy (kJ molS1U1P1-1S1S1P0)
C-C 347
C-H 414
C=C 611
C?C 837
H-H 436
A) -128 kJ molS1U1P1-1S1S1P0
B) +98 kJ molS1U1P1-1S1S1P0
C) +700 kJ molS1U1P1-1S1S1P0
D) -102 kJ molS1U1P1-1S1S1P0
E) -166 kJ molS1U1P1-1S1S1P0

Accepted Answer

We can determine ΔS1U1B1rS1U1B0H°S1U1B1 using bond energies by calculating the total energy required to break the bonds in the reactants and the total energy released in the formation of bonds in the products.

Reactants:
- 1 C-C bond (347 kJ/mol) 
- 2 C-H bonds (2 x 414 kJ/mol)
- 1 S-H bond (436 kJ/mol)

Products:
- 1 C-C bond (347 kJ/mol)
- 2 C-H bonds (2 x 414 kJ/mol)
- 1 C-S bond (240 kJ/mol)
- 1 S-H bond (436 kJ/mol)

ΔS1U1B1rS1U1B0H°S1U1B1 = ∑(bonds broken) - ∑(bonds formed)
ΔS1U1B1rS1U1B0H°S1U1B1 = (1 x 347) + (2 x 414) + (1 x 436) - (1 x 347) - (2 x 414) - (1 x 240) - (1 x 436)
ΔS1U1B1rS1U1B0H°S1U1B1 = -128 kJ/mol

Therefore, the best choice is A, which represents a negative value for ΔS1U1B1rS1U1B0H°S1U1B1, indicating that the reaction releases energy (exothermic) and is more stable in terms of energy compared to the reactants.

Quiz 9: Chemical Bonding I: Lewis Theory

Place the following in order of increasing bond length. C-F C-S C-Cl

Place the following elements in order of decreasing electronegativity. S Cl Se

Place the following in order of decreasing XO bond length, where "X" represents the central atom in each of the following compounds or ions: SiO₃²⁻ CO₂ CO₃²⁻

Which compound has the highest carbon-carbon bond strength?

Use the bond energies provided to estimate ?_rH° for the reaction below. XeF₂ +2F₂ ? XeF₆?_rH°= ? Bond Bond Energy (kJ mol^-1) Xe-F 147 F-F 159

Choose the bond below that is the weakest.

Place the following in order of decreasing bond length. H-F H-I H-Br

Use the bond energies provided to estimate Δ_rH° for the reaction below. 2Br₂(l) + C₂H₂(g) → C₂H₂Br₄(l) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) Br-Br 193 C≡C 837 C-C 347 C-Br 276 C-H 414

Place the following elements in order of increasing electronegativity. K Cs P

Rank the following molecules in decreasing bond energy. Cl₂ Br₂ F₂ I₂

Place the following in order of increasing bond length. NO₂⁻ NO₃⁻ NO

Which of the following processes is exothermic?

Which of the following processes is endothermic?

Use the bond energies provided to estimate Δ_rH° for the reaction below. PCl₃(g) + Cl₂(g) → PCl₅(l) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) Cl-Cl 243 P-Cl 331

Which of the following processes is exothermic?

Choose the bond below that is the weakest.

Which of the following processes is endothermic?

Use the bond energies provided to estimate Δ_rH° for the reaction below. CH₃OH(l) + 2O₂(g) → CO₂(g) + 2H₂O(g) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) C-H 414 C-O 360 C=O 799 O=O 498 O-H 464

Which compound has the longest carbon-carbon bond length?

Use the bond energies provided to estimate ?_rH° for the reaction below. C₂H₄(g) + H₂(g) ? C₂H₆(g) ?_rH°= ? Bond Bond Energy (kJ mol^-1) C-C 347 C-H 414 C=C 611 C?C 837 H-H 436

Quiz 9: Chemical Bonding I: Lewis Theory

Place the following in order of increasing bond length. C-F C-S C-Cl

Place the following elements in order of decreasing electronegativity. S Cl Se

Place the following in order of decreasing XO bond length, where "X" represents the central atom in each of the following compounds or ions: SiO32⁻ CO2 CO32⁻

Which compound has the highest carbon-carbon bond strength?

Use the bond energies provided to estimate ?rH° for the reaction below. XeF2 +2F2 ? XeF6 ?rH°= ? Bond Bond Energy (kJ mol-1) Xe-F 147 F-F 159

Choose the bond below that is the weakest.

Place the following in order of decreasing bond length. H-F H-I H-Br

Use the bond energies provided to estimate ΔrH° for the reaction below. 2Br2(l) + C2H2(g) → C2H2Br4(l) ΔrH° = ? Bond Bond Energy (kJ mol-1) Br-Br 193 C≡C 837 C-C 347 C-Br 276 C-H 414

Place the following elements in order of increasing electronegativity. K Cs P

Rank the following molecules in decreasing bond energy. Cl2 Br2 F2 I2

Place the following in order of increasing bond length. NO2⁻ NO3⁻ NO

Which of the following processes is exothermic?

Which of the following processes is endothermic?

Use the bond energies provided to estimate ΔrH° for the reaction below. PCl3(g) + Cl2(g) → PCl5(l) ΔrH° = ? Bond Bond Energy (kJ mol-1) Cl-Cl 243 P-Cl 331

Which of the following processes is exothermic?

Choose the bond below that is the weakest.

Which of the following processes is endothermic?

Use the bond energies provided to estimate ΔrH° for the reaction below. CH3OH(l) + 2O2(g) → CO2(g) + 2H2O(g) ΔrH° = ? Bond Bond Energy (kJ mol-1) C-H 414 C-O 360 C=O 799 O=O 498 O-H 464

Which compound has the longest carbon-carbon bond length?

Use the bond energies provided to estimate ?rH° for the reaction below. C2H4(g) + H2(g) ? C2H6(g) ?rH°= ? Bond Bond Energy (kJ mol-1) C-C 347 C-H 414 C=C 611 C?C 837 H-H 436

Place the following in order of decreasing XO bond length, where "X" represents the central atom in each of the following compounds or ions: SiO₃²⁻ CO₂ CO₃²⁻

Use the bond energies provided to estimate ?_rH° for the reaction below. XeF₂ +2F₂ ? XeF₆?_rH°= ? Bond Bond Energy (kJ mol^-1) Xe-F 147 F-F 159

Use the bond energies provided to estimate Δ_rH° for the reaction below. 2Br₂(l) + C₂H₂(g) → C₂H₂Br₄(l) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) Br-Br 193 C≡C 837 C-C 347 C-Br 276 C-H 414

Rank the following molecules in decreasing bond energy. Cl₂ Br₂ F₂ I₂

Place the following in order of increasing bond length. NO₂⁻ NO₃⁻ NO

Use the bond energies provided to estimate Δ_rH° for the reaction below. PCl₃(g) + Cl₂(g) → PCl₅(l) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) Cl-Cl 243 P-Cl 331

Use the bond energies provided to estimate Δ_rH° for the reaction below. CH₃OH(l) + 2O₂(g) → CO₂(g) + 2H₂O(g) Δ_rH°= ? Bond Bond Energy (kJ mol^-1) C-H 414 C-O 360 C=O 799 O=O 498 O-H 464

Use the bond energies provided to estimate ?_rH° for the reaction below. C₂H₄(g) + H₂(g) ? C₂H₆(g) ?_rH°= ? Bond Bond Energy (kJ mol^-1) C-C 347 C-H 414 C=C 611 C?C 837 H-H 436