Ball State University
Chemistry Analysis
CHEM 225
Laboratory Report
Experiment No. 9
Experiment: Preparation and Standardization of KI_3 and Iodimetric Analysis of
Tartar Emetic for Antimony
Name: Haley N. Snyder
Date: 03/17/2014
I.
Introduction
Throughout the procedures of the lab experiment, titrations were performed to analyze
known and unknown substances. Experiment I-3 consisted of the titration process a receiving
beaker with an iodide solution in order to eventually reach an endpoint of an arsenic solution.
I.
Procedures
The following procedures were performed within the lab: I-3 Preparation and Standardization
of N/10 I_3, I-4 Iodiometric Analysis of Tartar Emetic for Antimony.
II.
Equipment and Reagents
I-3
The following equipment and reagents were used within the experiment in addition to the
general equipment and tools available in general lab equipment drawers: Iodine reagent grade
solid, Potassium Iodide reagent grade solid, N/10 KI_3 solution preparation, Arsenic
Trioxide primary standard grade solid, Phenolphthalein indicator solution, Sodium
Bicarbonate reagent grade solid, Starch indicator solution.
I-4
The following equipment and reagents were used within the experiment in addition to the
general equipment and tools available in general lab equipment drawers: Tartar emetic
unknown sample, Sodium Potassium Tartrate reagent grade solid, standard N/10 KI_3
solution, Starch indicator solution.
III.
Data, Graphs and Statistics
I-3
The following table represents the resulting volumetric measurement of the three titration
trials as well as the calculated results of the molarity of I_3_^-3:
g As_2_O_3
0.8002 g
mL Iodine
39.9 mL
39.7 mL
39.8 mL
Mean: 0.040650 mol
Standard Deviation: 1.02x10^-4
Q-Test: 0.500<0.941 (data must be contained)
Moles of I_3_^0.040548 mol
0.040752 mol
0.040650 mol
I-4
The following table represents the resulting volumetric measurements of the three titration
trials as well as the calculated percent antimony present within the unknown (A):
g Unknown A
0.7564 g
0.7542 g
0.7544 g
Mean: 17.57%
mL Iodine
26.7 mL
26.9 mL
26.8 mL
% Sb present
17.47%
17.65%
17.58%
Standard Deviation: 0.09083
Q-Test: 0.611<0.941 (data must be retained)
IV.
Discussion
Throughout this processes of the experiment, many transfers of substances took place
whether it was due to weighing samples on the weighing docs or simply transferring one
liquid from one beaker to another flask. However, no matter what was being weighed or
measured out, precautionary measures were taken when doing all procedures.
I-3
Due to the dark red tint of the titration solution within the first portion of the lab, when
analyzing the volumetric measurement on the burette, seeing which lines the meniscus fell on
was difficult. With the possibility of not being able to differentiate between 0.1 mL could
have resulted in an area of error within the measurement portion of the titration process. The
slight error in the measurement of the titration portion could have served as a slight variation
of the calculations of the results in molarity.
Before beginning with the titrating process, the absolute certainty of all precipitate dissolving
was vital before proceeding with the rest of the experiment. The lack of 100% of the
precipitate dissolving would later cause a variation in the titration volume measurements
which would also cause a variation in the calculations of the molarity. Within this particular
experiment, the certainty that all the precipitate was gone was attained.
I-4
When adding NaHCO_3 to the receiving beaker solution, watching for bubbles determined
when the addition of the substance would cease. With the reliability of human eye to
determine when the bubbles had stopped forming within the solution could have served as
human error which could have been controlled. The addition of too much NaHCO_3 would
alter the resulting titration volumetric measurements after the color change was verified.
The dark purple color change was quire sudden and very sensitive to who mush titration
solution was added to the receiving beaker solution. The addition of too much titration
solution would cause an inaccurate volumetric measurement of how much titration solution
was utilized. This as well as the above state processes will also affect the resulting outcome
of calculations of the percent antimony present within the unknown sample being analyzed.
V.
References
There were no references used within this lab report other than what was provided within lab
as well as the reference to the lab manual for instructions.