problem set 3 417 2012 - Personal Pages - Denison University

Problem Set #3 Chem 417
October 22, 2012 Due Monday November 5, 2012 Fall 2012
Unit 4 on Acid–Base & Donor–Acceptor Chemistry.
INSTRUCTIONS. Please solve these problems on your own paper in this order. Problems adapted from Bowser,
Inorganic Chemistry; Miessler & Tarr, Inorganic Chemistry, 2nd Ed.; Rayner-Canham & Overton, Descriptive
Inorganic Chemistry, 4th Ed.
1. List the following acids in order of increasing acid strength with ammonia as the base.
Explain your selected ordering.
BF3, B(CH3)3, B(CH2CH3)3, B(Ar)3; (Ar = 2,4,6-trimethylphenyl)
2. For each of the following compounds, if a reaction will occur, give the balanced equation
for the reaction of the compound with water. Identify species acting as acids and as bases.
CaH2, HBr, H2S, CH4
3. Which of the following compounds is the strongest Brønsted acid Explain the reasoning
behind your selection.
SnH4, SbH3, TeH2
4. Which of the following compounds is the weakest Lewis base to trimethylboron Explain
the reasoning behind your selection.
pyridine, 2-methylpyridine, 2-ethylpyridine
5. In the following reactions, identify the acid and the base.
a. PCl5 + ICl → PCl4 + + ICl2 –
b. Pt + XeF4 → PtF4 + Xe
c. NOF + ClF3 → NO + + ClF4 –
d. Al2Cl6 + 2 PF3 → 2 Cl3Al–PF3 (note Al2Cl6 has bridging chlorines and no bond
between the aluminum atoms)
6. Liquid bromine trifluoride (BrF3) undergoes self-ionization. Write the balanced chemical
equation that represents this process.
1

7. In the following solution equilibria, use the concepts of hard-soft acid-base chemistry to
predict if the products or reactants will be favored in each of the following reactions.
Explain your answers.
a. AgF(aq) + LiI(aq) AgI(aq) + LiF(aq)
b. 2 Fe(OCN)3(aq) + 3 Fe(SCN)2(aq) 2 Fe(SCN)3(aq) + 3 Fe(OCN)2(aq)
c. 2 CuCN(aq) + CuI2(aq) 2 CuI(aq) + Cu(CN)2(aq)
8. Each of the following reactions lies toward the product side. On this basis only (without
reference to pKa data tables) arrange all of the compounds that act as Brønsted acids in
these reactions (there are five) in order of decreasing strength.
H3PO4(aq) + N3 – (aq) HN3(aq) + H2PO4 – (aq)
HN3(aq) + OH – (aq) H2O(l) + N3 – (aq)
H3O + (aq) + H2PO4 – (aq) H3PO4(aq) + H2O(l)
H2O(l) + PH2 – (aq) PH3(aq) + OH – (aq)
9. Use the Drago parameters to calculate the approximate enthalpy change for:
a. SO2 + C5H5N → C5H5N·SO2
b. Me3N·BF3 + PMe3 → Me3P·BF3 + NMe3
c. Me3Al·NMe3 + F3B·SEt2 → Me3Al·SEt2 + F3B·NMe3
(See Table 6.8. For PMe3, CB = 6.55; EB = 0.838)
2