Chem 1B
Chapter 20/21 Class Exercises
1.
Name: _____________________
Rank the following elements in order of increasing: (i) atomic radius; (ii) ionization energy, and (iii)
chemical reactivity:
(a) Li, Na, K, Rb, Cs;
(b) Li, B, N, F;
(c) F, Cl, Br, I;
(d) Al, C, N, Si;
2.
3.
Which of the following ionization processes requires (i) the least energy; (ii) the most energy? Explain.
(a) Na(g)  Na+(g) + e-;
(b) Mg(g)  Mg+(g) + e-;
(c) Na+(g)  Na2+(g) + e-;
(d) Mg+(g)  Mg2+(g) + e-;
Complete and balance the following reactions:
(a) __Li(s) + __ N2(g)  ?
(b) __Li(s) + __ O2(g)  ?
(c) __Na(s) + __ H2O(l)  ?
(d) __Ca(s) + __ H2O(l)  ?
(e) __Mg(s) + __HCl(g)  ?
(f) __CH4(g) + __H2O(g)  ?
(g) __Al2O3(s) + __H2SO4(aq) 
(h) ___KO2(s) + ___CO2(g) 
(i) ___NaHCO3(s) + heat 
(j) ___CaO(s) + ___SO2(g) 
(k) ___P4O10(s) + ___H2O(l) 
(l) ___Na2CO3(aq) + ___HCl(aq) 
Chem 1B
Chapter 20/21 Class Exercises
4.
Name: _____________________
Ammonia is produce according to the following equation:
N2(g) + 3 H2(g)  2 NH3(g);
Ho = -92 kJ
(a) Does the formation of ammonia favor high temperature or low temperature? Explain.
(b) Does the formation of ammonia favor high pressure of low pressure? Explain.
(c) Ho many grams of ammonia are produced by reaction of 1.00 m3 of hydrogen gas, measured at STP,
and an excess of nitrogen gas?
(c) How many cubic meters (m3) of N2 and H2, respectively, measured at STP, are required to produce
908 kg of NH3? (Assume the yield is 100%).
5.
6.
Draw Lewis structures for the following molecules. Predict their molecular shapes, and indicate
whether polar or nonpolar. Propose orbital hybridization on the central atom in each molecule.
(a) XeF2
(b) XeF4
(c) XeO2F2
(d) XeOF4
(a) Balance the following equation for the reaction between aluminum and ammonium perchlorate:
___Al(s) + ___NH4ClO4(s)  ___Al2O3(s) + ___AlCl3(s) + ___N2(g) + ___H2
(b) How many kilograms of aluminum will react with 1.00 metric ton (103 kg) of ammonium
perchlorate. (Assume 100% efficient)
(c) Given the following thermodynamics data:
Hof (kJ/mol):
NH4ClO
-295
Al2O2
-1676
AlCl3
-704
H2O
-242
Calculate the enthalpy change for the above reaction (after it is balanced)
Ho = ?
Chem 1B
Chapter 20/21 Class Exercises
7.
Name: _____________________
Write the electron configuration and draw the orbital “box” diagram for the valence-shell electrons in
the following ions using appropriate noble gas symbols for the inner-shells. Identify the ion that is
diamagnetic, least paramagnetic, and the most paramagnetic ion.
(a) Cr :
(b) Cr3+ :
(c) Fe :
(d) Fe3+ :
(e) Zn2+ :
8.
Name the following coordination compounds using systematic nomenclature.
(a) [Cr(NH3)6]Cl3:
(b) Na[Au(CN)4]:
(c) [Co(en)2Cl2]Cl:
9.
Write the Werner’s formula for the following coordination compounds:
(a) Diamminedichloroplatinum(II) =
(b) Diaquabis(ethylenediamine)chromium(III) chloride =
(c) Potassium hexacyanocobaltate(III) =
10.
Draw the structures of all possible isomers of the complex ion [Cr(en)2(NO2)2]+ and indicate which
isomers are optically active.
Chem 1B
Chapter 20/21 Class Exercises
Name: _____________________
11.
The octahedral complex ion [CoF6]3- is paramagnetic with four unpaired 3d-electron, whereas complex
ion [Co(CN)6]3- is diamagnetic. Draw the crystal-field energy diagram of 3d-orbitals in each complex.
Which ligand causes a larger splitting of d-orbitals?
12.
Aqueous solution of the complex ion [Co(H2O)6]2+ absorbs green light at max = 512 nm. (a) What is the
color of the solution? (b) Calculate the octahedral crystal-field splitting energy (expressed as kJ/mol) in
the complex ion [Co(H2O)6]2+.