titrations worksheet...a. equal to 7 b. less than 7 c. greater than 7 11. at the equivalence point,...
TRANSCRIPT
Titrations Worksheet
“In an acid–base titration, a solution containing a known concentration of base is slowly added to an acid (or
the acid is added to the base). Acid–base indicators can be used to signal the equivalence point of a titration
(the point at which stoichiometrically equivalent quantities of acid and base have been brought together). The
shape of the titration curve makes it possible to determine the equivalence point. The curve can also be used to
select suitable indicators and to determine the Ka of the weak acid or the Kb of the weak base being titrated.”
1. What is the purpose of a titration?
2. What does the phrase “stoichiometrically equivalent” mean?
3. When you draw a titration curve what is on the X-axis? And the Y-axis?
4. Match the following words and definitions:
a. Titrant
b. Analyte
c. Standardized
d. Equivalence Point
e. End Point
f. Indicator
5. A) On the titration curve on the back of this sheet is there a “buffer region”? B) In what 2 combinations
of analyte/titrant do we see this region arise? C) What is the significance of the “Half-equivalence
point”?
6. Fill in the following table:
Analyte/Titrant pH at equivalence point
SA/SB
pH=7
pH>7
WB/SA
7. What are the 4 considerations when choosing an indicator?
i. Known to good precision
ii. Where the titration is theoretically done
iii. Stuff in the burrette
iv. What is being analyzed
v. How we see the reaction is over
vi. Where we see the reaction is over
8. What type of acid yields a weird 2 humped titration curve?
9. Calculate the pH at the equivalence point in the titration of 50.0 mL of 0.100 M CH3COOH with 0.100
M NaOH. (Ka=1.8 ∙ 10-5
)
The next 3 questions are concerning the titration of CH3COOH with KOH.
10. The pH at the equivalence point will be ___.
A. equal to 7
B. less than 7
C. greater than 7
11. At the equivalence point, what is in the flask?
A.CH3COOH, H2O and KCH3COO
B.KOH, CH3COOH and H2O
C.KOH, KCH3COO and H2O
D.CH3COOH and H2O
E.H2O and KCH3COO
F.KOH, CH3COOH, H2O and KCH3COO
12. True or false. A titration curve of this titration (CH3COOH with KOH) would not have a buffer region.
13. What type of titration is this? ( SA/SB, SB/SA, WA/SB, or WB/SA)
14. Which point on the curve represents the equivalence point?
15. At which point is the pH equal to the pKa?