302 ❯ STEP 4. Review the Knowledge You Need to Score High
Use the following diagram for questions 6 and 7.
0G H
Volume strong acid addedEpH FThe diagram above represents the idealized titration
curve for the reaction of sodium oxalate (Na 2 C 2 O 4 )
with a strong acid like hydrochloric acid (HCl). E
and F represent the pH at the endpoints. G and H
will depend on the composition of the sample with
the possibility that one may not be present.
- A trial run used a sample of pure sodium oxalate.
How does the volume of acid necessary to reach
G compare to the volume of acid necessary to
get from G to H?
(A) The volumes required will be the same.
(B) A larger volume is necessary to reach G.
(C) A larger volume is necessary to get from G
to H.
(D) It is impossible to determine. - In addition to water, what are the predominant
species in solution at E?
(A) Na 2 C 2 O 4 and HCl
(B) Na+, Cl-, and HC 2 O 4 -
(C) C 2 O 42 - and H+
(D) Na+, H+, and C 2 O 42 -
8. A student is attempting to prepare an electrochem-
ical cell, which ideally should produce 1.23 V.
Unfortunately, he was unable to make a salt
bridge. He reasoned that a copper wire would
conduct electricity like a salt bridge, so he used
a copper wire in place of the salt bridge. How
will the voltage of the cell with the copper wire
compare to that of the ideal cell?
(A) The voltage is ideal.
(B) The voltage becomes zero.
(C) The voltage is greater than ideal.
(D) The voltage less than ideal but greater than
zero.
9. A chemist constructs an electrochemical cell
with a magnesium anode and a copper cathode.
She measures the cell voltage. Next, she replaces
the copper electrode with a larger copper elec-
trode. What does she find when she measures
the cell voltage of the cell with the larger copper
electrode?
(A) There is no change in the voltage.
(B) The voltage becomes zero.
(C) The voltage increases.
(D) The voltage decreases but stays positive.
10. While investigating a radioactive decay process,
a chemist constructs a linear graph. What infor-
mation did she plot?
(A) She plotted the concentration remaining
versus time.
(B) She plotted the natural logarithm of the
concentration remaining versus time.
(C) She plotted the reciprocal of the concentra-
tion remaining versus time.
(D) She plotted the natural logarithm of the
concentration remaining versus the inverse
of the time.