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J-5
a)
Write the balanced net ionic equation for the reaction between cadmium nitrate, Cd(NO3)2, and
sodium oxalate, Na2C2O
4
.
b)
In each of the following test tubes, 5.0 mL of 0.10 M Cd(NO3)2 and 5.0 mL of
0.10 M Na2C2O
4
were combined and allowed to stand for 10 minutes in order to reach
equilibrium. The following additions were made to these test tubes:
test tube #1 -
2.0 mL of distilled water
test tube #2 -
2.0 mL of 1.0 M HCl, hydrochloric acid
test tube #3 -
2.0 mL of 1.0 M HNO3, nitric acid
The solutions were mixed thoroughly, allowed to stand to reach equilibrium again, then the
observations were recorded.
Using LeChatelier's Principle, explain how the reaction in part a) of this question would be
affected by these additions. Give the expected visual observations and include all appropriate
interactive equilibria in your answers.
(4.0)
16.
(Exp F) In performing this experiment, the equilibrium for the following reaction was studied:
I
2(aq)
+ I
-
(aq)
I3
-
(aq)
,
A student determined that the total concentration of ( I2 and I3
-
) in the aqueous layer was
0.0120 M. Calculate:
a)
the [I3
-
] in the aqueous layer, given that [I
2(aq)
] was 2.10 x 10
-4
M
b)
the [I
-
] in the aqueous layer, given that the original KI3 solution was prepared from
0.100 M KI.
c)
the equilibrium constant, K
eq
, using your answers from parts a) and b)
(4.0)
17.
(Exp G) In a titration of an acetic acid (CH3COOH) solution of unknown concentration, a 28.18 mL
sample of the acid is required 28.73 mL of a 0.2110 M KOH solution to reach the equivalence point.
a)
Determine the initial concentration of CH3COOH.
b)
What ions in significant concentrations are present in the solution at the equivalence point?
Support your answer with the appropriate balanced chemical equations.
c)
What is the concentration of the conjugate base at the equivalence point?
d)
What is the percent dissociation, given an initial pH of 2.82.
e)
Determine the pH of the solution at the equivalence point.
BONUS QUESTION
