Inorganic Chemistry. Structure and Applications (CHEM 2400)
____________________________________________________________ Experiment 8
Preparation of Potassium Iodate
Iodic acid, HIO3, the only one of the halogenic acids, HXO3, which can be isolated as the anhydrous compound,
forms colourless, transparent crystals. It acts as a medium-strong acid and as a strong oxidizing agent.
Iodates, MIO3, behave in solution in many ways like chlorates and bromates. The iodates are much more stable than
chlorates and bromates, however, they can explode when mixed with organic material and carbon and heated.
Iodates are also less soluble in water. They are also oxidizing agents.
The most probable conclusion is that the anion of the ordinary iodates is the simple IO3─. Sodium iodate occurs in nature on Chile saltpetre, which is the main source of iodine.
Like potassium bromate, potassium iodate is occasionally used as a maturing agent in baking. Potassium iodate may
be used to protect against accumulation of radioactive iodine in the thyroid by saturating the body with a stable
source of iodine prior to exposure.
Part I
Preparation of Potassium Iodate
Fill a 600 mL beaker with distilled water, put it on a hot plate, and bring to boil. Thoroughly grind approximately
7.7-7.8 g of potassium permanganate, KMnO4, to a powder using a mortar and a pestle. Weigh out 7.5 g of this
powder on a weighing paper and transfer it into a 100-mL beaker. Add 30 mL of boiling water using a graduated
cylinder and mix it thoroughly with a glass rod.
Crush approximately 3.7-3.8 g of solid iodine, I2, in a second mortar. Weigh out 3.5 g of this powder and transfer it in
very small portions into the KMnO4 solution. Keep stirring with a rod. Note the original colour of this mixture. Add
4 pellets of potassium hydroxide and approximately 0.2 g of potassium iodide, KI, while stirring in the middle of the
iodine addition to initiate the reaction. Rinse off the walls of the beaker with no more than 25-30 mL of boiling
water. Turn off the hotplate (as it is still hot), put the beaker on it, and continue stirring until the colour of potassium
permanganate completely disappears. By using a Pasteur pipet, add 1 drop of the reaction mixture onto filter paper.
Your reaction is complete if you observe a drop of a brown suspension surrounded by a circle of colourless liquid.
Otherwise keep stirring until this is the case. Insert a Büchner flask into a water bath with hot tap water and preheat
it. Put 2-3 layers of filter paper onto the funnel. Filter the hot reaction mixture and rinse the beaker with a small
amount of boiling water (try not to exceed the final volume of 100 mL of the filtrate). The filtrate should be
colourless. This is an indication that the reaction between permanganate and iodide in a basic medium is complete.
Transfer the filtrate into a large evaporating dish and evaporate up to 1/3 of the original volume on a hotplate (in the
fume hood!). Do not forget to put 2-3 small chunks of boiling chips into it. Put the dish on ice and start stirring with
a clean glass rod until crystals start forming. Cool approximately 100 mL of distilled water on an ice bath. Filter the
content of the evaporating dish using a glass crucible (weighed in advance) of F porosity (consult your instructor or
TA) and wash the precipitate from the evaporating dish using this cold water.
Put the crucible into a beaker and dry it in an oven at 120 °C for about 15-20 minutes. ____________________________________________________________
Laboratory Manual - 2017 Experiment #8: page 1 of 2 Inorganic Chemistry. Structure and Applications (CHEM 2400)
____________________________________________________________
Part II
Prepare 10 mL of approximately 1% silver nitrate solution.
Put a small amount of potassium iodate crystals into a test tube and add the silver nitrate solution dropwise until you
observe the precipitate formation.
Decant the liquid from the precipitate and add concentrated nitric acid dropwise to the precipitate using a Pasteur
pipet. Record your observation. Repeat the same reactions with your potassium periodate.
Identification of the product by powder X-ray diffraction: Identification of product by powder X-ray diffraction
Your synthesis product needs to be identified by powder X-ray diffraction. Mount your sample
on the provided sample holder. Place the sample holder in the powder X-ray diffractometer
position according to your work bench label. Your sample will be measured from 10 to 90˚ in 2θ
using a step width of 0.02Ëš. Your diffractogram will be deposited on UMLearn: CHEM2400: Xray Data labeled with your work bench position, the weekday of your laboratory and the
experiment number. You will have to identify your product using MATCH! and provide a
printout of your diffractogram with the matching database entry. Clearly state if the expected
product was formed. Provide comments if you do not obtain or cannot identify the expected
product.
Questions 1. H2 O
D excess F2
C F2
Xe RBF2 , where R is an organic group
A
B E 2. What is the density of 53.4 % aqueous NaOH if 16.7 mL of the solution diluted to 2.00 L gives
0.169 M NaOH? ____________________________________________________________
Laboratory Manual - 2017 Experiment #8: page 2 of 2

 

• 1503557112-Experiment-8-2017 1.pdf

AccountingQueen

(3)

Status NEW Posted 24 Aug 2017 06:08 AM My Price 10.00

Hel-----------lo -----------Sir-----------/Ma-----------dam----------- T-----------han-----------k y-----------ou -----------for----------- us-----------ing----------- ou-----------r w-----------ebs-----------ite----------- an-----------d a-----------cqu-----------isi-----------tio-----------n o-----------f m-----------y p-----------ost-----------ed -----------sol-----------uti-----------on.----------- Pl-----------eas-----------e p-----------ing----------- me----------- on----------- ch-----------at -----------I a-----------m o-----------nli-----------ne -----------or -----------inb-----------ox -----------me -----------a m-----------ess-----------age----------- I -----------wil-----------l

Not Rated(0)

• Buy Answer