Name:_____________
Chemistry 114
Fourth Hour Exam
Remember- Show all work for partial credit
All questions are worth 12 points
1. If I mix 5 mLs of .05M Pb(NO3) with 11 mLs of .05M NaCl
A. What is the concentration of Pb2+ in the resulting solution?
B. What is the concentration of Cl- in the resulting solution?
C. If the K for the reaction PbCl2(s) WPb2+(aq) + 2 Cl-(aq) is 1.6 x 10-5, will a
precipitate form in this solution? Why or why not?
2. If the reaction N2(g) + 3 H2(g) W2NH3 (g) is at equilibrium.
Will the relative amount of NH3 increase if I?
A. Remove H2 gas from the system
B. Reduce the volume of the system
C. Add Ar gas to the system
D. Increase the temperature of the system (the reaction is exothermic)
2
3. Calculate the pH of the following solutions
A. 0.0067 M HCl
B. 0.0067 M Ca(OH)2
C. 0.0067 M CH3COOH (Ka = 1.75x10-5)
D. 0.0067 M CH3NH2 (Kb = 4.38x10-4)
4. Arrange the following 0.1M solutions from most acidic to least acidic
KOH, KNO2, HNO2, Ba(OH)2, KNO3, HNO3
Most
Least
Cu(NO3)4, PO3, NH4Cl, HClO4, HClO3, NaClO4, NaClO3
Most
Least
3
5. I am going to mix 50 mL of 0.1M Acetic Acid with 35 mL of 0.1M NaOH. What is the
pH of the resulting solution? (The pKa of acetic acid is 4.76)
6. Define the following terms
% Ionization
Free energy
Equivalence point
2nd Law of Thermodynamics
Reaction quotient
Lewis base
4
7.Predict the ÄS (+ or -) for the following processes or reactions:
H2O(l) 6 H2O(g)
I2(g) 6I2(l)
2H2S(g) + SO2(g) 6 3Srhombic(s) + 2H2O(g)
2CH3OH(g) + 3O2(g) 6 2CO2(g) + 4H2O (g)
8. Calculate ÄG0 for the following reaction
HCl(g) + NH3(g) 6 NH4Cl(s)
Given the following information:
ÄH f
ÄG f
kJ/mol
kJ/mol
HCl(g)
-92
-95
HCl(aq)
-167
-131
NH3(g)
-46
-17
NH3(aq)
-80
-27
NH4+(aq)
-132
-79
NH4Cl(s)
-314
-203
NH4Cl(aq)
-299
-210
So
J/K@mol
187
57
192
111
113
96
170
For the last 4 points, calculate Keq for the above reaction from your ÄG.