DESCRIPTIVE INORGANIC CHEMISTRY
April 2, 2013
INSTRUCTIONS:
PRINT YOUR NAME ————> NAME
QUIZ III
___________________
.
SHOW YOUR WORK FOR PARTIAL CREDIT
THERE IS A PERIODIC TABLE AND A TABLE OF BOND ENERGIES ATTACHED
THE LAST PAGES ARE a Table of Bond energies and A Periodic Table
Work 5 of these (20 pts each)
R = 0.08206 lit-atm/mol-K
R = 8.3145 J/mol-K
1
(20)
2
(20)
h = 6.626 X 10-34 J-s
3
(20)
c = 2.9979 X 108 m/s
4
(20)
2
2
J = (kg-m )/s
5_______(20)
6_______(20)
7_______(20)
TOTAL(100)
l
1. Given the following data, construct the Born-Haber cycle to estimate the Enthalpy of
formation for NaH from Na(s) and H2(g). Bond energies are in an attached appendix.
(Remember this is for formation of one mole of the NaH) (Caution: I have included
some irrelevant data in the table.)
Enthalpy Values
Na atomization
1st electron affinity of Na
1st ionization of Na
2nd ionization of Na
1st Electron affinity of H
1st Ionization energy of H
Estimated lattice energy NaH
kJ/mol
+107
-53
+496
+4560
-73
+1312
-808
2. Given that the enthalpy of atomization of one mole of S is +227 kJ/mol,
That is 1/8S8(s)  S(g) ΔH = +227 kJ/mol.
Estimate the enthalpy of formation of SF6 (one mole) from S8(s) and F2(g) using a
diagram like a Born-Haber cycle. Bond energies are listed in a table at the back of the
quiz.
3. (a) Classify the bonding in the highest oxidation number main group oxides fluorides
of the 4th period as ionic, network, or covalent. All melting points are in °C
KO2
CaO
Ga2O3
GeO2
As2O5
SeO3 BrO2
380
2900
1725
1116
315
118
-40
(b) Why does the melting point increase in going from KO2 to CaO?
(c) Ga2O3 might be expected to have a higher melting point than CaO, but it is lower.
What is a possible explanation for this lower than expected value?
4. Answer the following concerning acid base theory
Which is the stronger acid and explain your answer in (a) and (b)
(a) H-ClO
(c) Ca2+ (aq)
H –ClO2
Al3+( aq)
__________________________________________
___________________________________________
Which is the stronger base and explain your answer in (c), (d), and (e)
(c) ClO-(aq)
(d) ClO3(e)
O2-
ClO3-(aq)
CO32I-
___________________________________________
___________________________________________
___________________________________________
(f)Write the equation for the weak acid HClO2 reacting as a Brønsted-Lowry acid
towards water.
(g) Write the equation for the base CN- reacting as a Brønsted-Lowry base towards
water.
(h) Identify the Lewis acid and the Lewis base in the following reaction.
Explain your choice.
2CN-(aq) + Ag+(aq) 
Ag(CN)2-(aq)
(i and j)MgO is a basic oxide, and CrO3 is an acidic oxide with water. Write two separate
equations for these oxides reactiing with water
5. (a) For the reaction shown in (b), assign oxidation numbers to N and S in each
compound or ion. Identify which species is oxidized and which is reduced.
NO3- (aq)
N oxidation number______
NO(aq) N oxidation number______
SO2 (aq)
S oxidation number _____
SO42-(aq) S oxidation number _____
Species reduced ________________
Species oxidized ___________________
(b) Balance the following redox equation in acidic solution by the method of half
reactions. Show your work.
NO3- (aq)
+
SO2 (aq)
NO(aq)
+ SO42-(aq)
6. (a) Which of the following would you expect to be the harder acid according to
hard/soft-acid/base theory in each pair.
Ag+ or Li+ ________________________________
Co3+ or Ni2+ ____________________________________
.(b) Which of the following would you expect to be the harder base according to hard/soft
acid/base theory in each pair
O2- or S2- __________________________________________
SCN- or OH- _______________________________________
(SCN- bonding through the S atom)
(b) In the following aqueous solution equilibria, will the products or the reactants be
favored? Explain your reasoning.
AuCl2- (aq) + 2CN-(aq)
Au(CN)2- (aq) + 2Cl-(aq)
(c) Is the following reaction likely to occur in the gas phase? Give your reasons why.
3HgF2 (g)
+
2CoBr3(g)
3 HgBr2(g)
+
2CoF3 (g)
(d) Heavier metals ions like Hg2+ and Pb2+ or Cd2+ bind to enzymes and deactivate them.
Would you expect these ions to bind to oxygen or sulfur rich sites in enzymes? Explain
your choice.
7. (a)With which element do you expect to Cd to have a knight’s move relationship?
What are the oxidation states of the two metals? Describe the effect that that is used to
explain the knight’s move relationship.
(b) When magnesium nitrates and sulfate are crystallized from water the crystals that
come out are Mg(NO3)2•6H2O and MgSO4•7H2O, respectively. Identify the d-block
metal that forms a nitrate and a sulfate with the same number of water molecules in the
formulas, and also have similar crystal structures.
(c) Pick two elements from the periodic table that have a diagonal relationship. Name
two facts that illustrate this relationship. What explains the similarity in properties of
these two elements?
(d) What are three pairs of combo elements that can replace Ge as a semiconductor?
What is an advantage of using these substitution elements?
(e) Describe how strontium from radioactive fallout can be detrimental to living systems.