Ch.7 - Covalent Bonding and Electron-Dot Structures
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- Which compound do you expect to have the stronger N-N bond, N2H2 or N2H4? Explain.
Problem 76
- Ibuprofen 1C13H18O22, marketed under such brand names as Advil and Motrin, is a drug sold over the counter for treatment of pain and inflammation. Complete the structure of ibuprofen by adding hydrogen atoms and lone pairs where needed.
Problem 83
Problem 85b
Draw as many resonance structures as you can for the following nitrogen-containing compounds. Not all will obey the octet rule. Use curved arrows to depict the conversion of one structure into another. (b) NO
Problem 85d
Draw as many resonance structures as you can for the following nitrogen-containing compounds. Not all will obey the octet rule. Use curved arrows to depict the conversion of one structure into another. (d) N2O3(ONNO2)
- Which of the following pairs of structures represent resonance forms, and which do not? (a)
Problem 86
- The estimated lattice energy for CsF21s2 is +2347 kJ/mol. Use the data given in Problem 6.86 to calculate an overall energy change in kilojoules per mole for the formation of CsF21s2 from its elements. Does the overall reaction absorb energy or release it? In light of your answer to Problem 6.86, which compound is more likely to form in the reaction of cesium with fluorine, CsF or CsF2?
Problem 87
- Draw three resonance structures for sulfur tetroxide, SO4, whose connections are shown below. (This is a neutral mol-ecule; it is not a sulfate ion.) Assign formal charges to the atoms in each structure.
Problem 91
- Some mothballs used when storing clothes are made of naphthalene (C10H8), which has the following incomplete structure.
Problem 92
(a) Add double bonds where needed to draw a complete electron-dot structure.
- Four different structures (a), (b), (c), and (d) can be drawn for compounds named dibromobenzene, but only three different compounds actually exist. Explain. (a)
Problem 93
(b)
(c)
(d)
Problem 98
Assign formal charges to the atoms in the following structures. Which of the two do you think is the more important contributor to the resonance hybrid?(a)(b)
- Draw the resonance structure indicated by the curved arrows. Assign formal charges, and evaluate which of the two structures is a larger contributor to the resonance hybrid.
Problem 102
- Propose structures for molecules that meet the following descriptions. (b) Contains an N atom that has one p bond and two s bonds
Problem 110
- The dichromate ion, Cr2O72-, has neither Cr¬Cr nor O¬O bonds. (a) Taking both 4s and 3d electrons into account, draw an electron-dot structure that minimizes the formal charges on the atoms.
Problem 113
- Calculate an approximate heat of combustion for ethane (C2H6) in kilojoules by using the bond dissocation energies in Table 9.3. (The strength of the O'O bond is 498 kJ/ mol, and that of a C ' O bond in CO2 is 804 kJ/mol.)
Problem 118
- What is the difference between a covalent bond and an ionic bond?
Problem 134
- The reaction S81g2 S 4 S21g2 has ΔH° = + 237 kJ (b) The average S ¬ S bond dissociation energy is 225 kJ/mol. Using the value of ΔH° given above, what is the S ' S double bond energy in S21g2?
Problem 150
- When 0.500 mol of N2O4 is placed in a 4.00-L reaction vessel and heated at 400 K, 79.3% of the N2O4 decom- poses to NO2. (b) Draw an electron-dot structure for NO2, and rational- ize the structure of N2O4.
Problem 152