SID
Question 1
6 Points
Last
Key
First
Answer
With respect to the following acid base reactions, indicate whether the resulting solution
will be acidic, basic, or neutral:
1. When 35 mL of 0.400 M H2SO4 and 70 mL of 0.400 M
sodium nitrite are combined:
2. When 35 mL of 0.40 M HClO4 and 35 mL of 0.40 M
sodium hydroxide are combined:
3. When 50 mL of 0.20 M ammonium iodide and 50 mL of 0.20 M
potassium hydroxide are combined:
Question 2
6 Points
The following questions pertain to a buffer solution that is 0.204 M in HCN and 0.132 M in
Ka(HCN) = 6.2x10-10
NaCN.
1. Write the net ionic equation for the removal of added H3O+ to this buffer:
+ H3O+ =
+
2. What is the buffer capacity for addition of strong acid:
3. The choice of HCN suggests that the desired pH is close to:
Question 3
6 Points
Which of the following aqueous solutions are good buffer systems?
0.28 M ammonium bromide + 0.34 M ammonia
0.17 M hypochlorous acid + 0.22 M sodium hypochlorite
0.18 M sodium hydroxide + 0.28 M sodium chloride
0.16 M hydrochloric acid + 0.32 M sodium nitrite
Question 4
6 Points
Calculate the pH of a buffer solution that is 0.231 M in NH3 (ammonia) and 0.306 M in
NH4Br.
Use the ICE Method: Kb(NH3) = 1.8x10-5
pH =
Question 5
6 Points
1. When 19.1 mL of 0.400 M aqueous HF is titrated with a 0.347 M barium hydroxide
solution, what is the pH at the midpoint in the titration?
Ka(HF) = 3.5x10-4 @ 25oC
pH =
2. A 20.2 mL sample of 0.341 M ammonia, NH3, is titrated with 0.386 M hydroiodic
acid. The pH before the addition of any hydroiodic acid is?
Kb(NH3) = 1.8x10-5 @25oC
pH =
Question 6
6 Points
Question 7
6 Points
Rank the following salts from 1-3 in order of increasing solubility with 1 being the most
soluble and 3 being the least soluble.

AgCN
Ksp = 1.2x10-16

Zn3(PO4)2
Ksp = 9.1x10-33

CaF2
Ksp = 3.9x10-11
The maximum amount of zinc(II) phosphate that will dissolve in a 0.42 M sodium
phosphate solution is:
Zinc(II) phosphate: Ksp = 9.1x10-33
M
Question 8
4 Points
Write a balanced net ionic equation to show why the solubility of Mn(OH)2(s) increases in
the presence of a strong acid and calculate the equilibrium constant for the reaction of
this sparingly soluble salt with acid.
Must show work when calculating K – Ksp Mn(OH)2 = 4.6x10-14
+
=
+
K=
Question 9
4 Points
Question 10
6 Points
Rank the following substances from 1-4 in order of increasing entropy with 1 being the
lowest entropy and 4 being the highest entropy.

HCHO(g)

(CH3)2CO(g)

CH3OH(g)

CH3CHO(g)
Consider the reaction:
2 H2O2(l)
2 H2O(l) + O2(g)
Using standard absolute entropies at 298K, calculate the entropy change for the system
when 1.58 moles of H2O2(l) react at standard conditions?
So (J/K.mol):
H2O2(l): 109.6
O2(g): 205.1
H2O(l): 69.9
J/K
Question 11
6 Points
Consider the reaction:
o
2 CO(g) + 2 NO(g)
2 CO2(g) + N2(g)
o
for which H = -746.6 kJ and S = -198 J/K at 298 K.
Calculate the entropy change of the UNIVERSE when 3.14 moles of NO(g) react
under standard conditions at 298 K.

Question 12
6 Points
SoUniverse =
J/K
Is this reaction reactant or product favored?
A student determines the value of the equilibrium constant to be 3.9x1013 for the
following reaction.
4 HCl(g) + O2(g)
2 H2O(g) + 2 Cl2(g)
Based on this value of K:
Calculate the free energy change for the reaction of 1.57 moles of O2(g) at standard
conditions at 298K.
Must show work for full credit
Gorxn =
Question 13
6 Points
Question 14
6 Points
Question 15
5 Points
kJ
Without doing any calculations, match the following thermodynamic properties with
their appropriate numerical value given on the right for the following endothermic
reaction.
2 H2O(g) + 2 Cl2(g)
4 HCl(g) + O2(g)

Suniverse

Grxn

Srxn
1.
2.
3.
4.
5.
>
<
=
>
<
0
0
0
0 at low T, < 0 at high T
0 at low T, > 0 at high T
Write a balanced nuclear equation for the following:
a)
28
15P
b)
41
20Ca
undergoing positron emission:
undergoing electron capture:
60
27Co
=
=
is one of many radioactive isotopes whose #Neutron/#Proton ratio is too large.
Radioactive isotopes of this type have only one form of radioactive decay available to
them:
Alpha Emission
Electron Capture
Beta Emission
Positron Emission
Question 16
6 Points
What is the binding energy in kJ/mol nucleons for copper-65?
The required masses (g/mol) are:
1
1H
= 1.00783;
1
0n
= 1.00867;
65
29Cu
= 64.92780
kJ.mol-1.nucleons
Question 17
6 Points
An artifact classified as bone, found in a site at Klithi, Greece, is found to have a 14C
radioactivity of 0.0841 counts per second per gram of carbon. If living carboncontaining objects have an activity of 0.255 counts per second per gram of carbon,
estimate the age of the artifact?
The half-life of
14
C is 5730 years
years
Do Not Write Below This Line
Exam III Score