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Iodometric Titration Tutorial


-Introduction

-Calculating moles of KIO3 required.

-Calculating concentration of KIO3 solution.

-Calculating mass of KIO3 to prepare solution.

-Conclusion

-Practice Question: Virtual Lab



Experiment 9 Iodometric Titration Online Tutorial >> Preparation of a KIO3 Standard Solution >> Calculating moles of KIO3

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Exp 9: Iodometric Titration Online Tutorial - Preparation of a KIO3 Standard Solution

Step 1 - Calculating moles of KIO3

In this tutor, we will calculate the number of moles of KIO3 required to completely react with the ascorbic acid present in a sample to be titrated.

Suppose that the amount of ascorbic acid in the sample you are about to titrate is 10 mg. How many moles of KIO3 are required to completely react with this sample?
Hint
(Please give your answers to 5 significant figures; for very small numbers, use scientific notation i.e. 6.3e-8)
moles
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Hint:
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The following tutors are a step by step walkthrough that show the details of how to solve the above problem.

Part 1:

The titration of ascorbic acid with potassium iodate proceeds through a series of reactions:
Hint
KIO3 + 5KI + 6H+ → 3I2 + 6K+ + 3H2O
[1]
C6H8O6 + I2 → C6H6O6 + 2I- + 2H+
[2]
Based on these balanced reactions, what is the relationship between the moles of KIO3 consumed and moles of ascorbic acid consumed?
Select
1
2
3
4
mole(s) of C6H8O6 consumed for each 1 mole of KIO3 consumed.
Correct. 3 moles of ascorbic acid are consumed for each 1 mole of potassium iodate that is consumed in the titration reaction.
That's not quite right.
Hint:
How many moles of iodine produced in reaction [1] will be consumed by ascorbic acid in reaction [2]?
 
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Hint:
There are 3 moles of iodine produced in reaction [1]. For all of them to be consumed, how many moles of ascorbic acid are required?
 
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Hint:
3 moles of ascorbic acid are consumed for each 1 mole of potassium iodate.
 
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Part 2:

Our next task is to determine the number of moles present in our sample. How many moles of ascorbic acid are contained in a 10 mg sample of C6H8O6?

(Please give your answer to 5 significant figures; for very small numbers, you may use scientific notation i.e. 6.3e-8)
Hint
moles of ascorbic acid
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That's not quite right.
Hint:
The formula for ascorbic acid is C6H8O6. What is its formula weight?
 
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Hint:
The formula weight of ascorbic acid is 176.1 g/mol. Can you use this information to determine the number of moles present in the 10 mg sample?
 
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Hint:
To calculate moles of ascorbic acid, divide the number of grams in our sample by the formula weight, 176.1 g/mol.
 
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Hint:
The number of moles is: 0.010 g / 176.1 g/mol = 5.6786e-5 moles of ascorbic acid.
 
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Part 3:

How many moles of KIO3 are required to react with the calculated number of moles of ascorbic acid in our 10 mg sample?

(Please give your answer to 5 significant figures; for very small numbers, you may use scientific notation i.e. 6.3e-8)
Hint
moles of KIO3
Good Job!
That's not quite right.
Hint:
In part 1 we determined that 1 mole of potassium iodate is required for each 3 moles of ascorbic acid. Knowing this, how many moles of KIO3 will be required?
 
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Hint:
Using the moles of ascorbic acid calculated above, and the ratio from step 1, we find:
(5.6786e-5 mol ascorbic acid) * (1 mol KIO3 consumed / 3 mol C6H8O6 consumed) = 1.8929e-5 mol KIO3.
 
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Last Updated: Wednesday, January 11th, 2017 @ 10:31:25 am