[Hemidol]

From the volume of titrant added, calculate the moles of vitamin C for each titration. Show a sample
calculation for trial 1. From the results this, calculate the average value for the number of moles of vitamin C titrated. Report the final value to the appropriate number of significant figures.


Given these values:
concentration of KIO3 M:  0.002034
weight of tablet: 0.3g

trial #1:
final buret reading: 20mL
initial buret reading: 30mL
volume of KIO3: 10mL
weight of vitamin C tablet: 5g

trial #2:
final buret reading: 12mL
initial buret reading: 20mL
volume of KIO3: 8mL

The key reaction of this experiment was :
IO3- + 5I- + 6 H+ -> 3 I2 + 3 H2O

how can I do this?? This was an experiment involving identifying the compositon of vitamin C

[Hemidol]

Don't mean to double post but I can't edit my message... I have some further questions that I'm interested in answering here.

From the results of question 1, calculate the average value for the number of moles of vitamin C titrated.
Report the final value to the appropriate number of significant figures.

-- To answer this I would just take the mole value above (for trial 1); do the same thing for trial do, add them together and divide by 2--correct?

3. Calculate the % error of the mole values used to calculate the average in question 2.

Not sure how I do this.

Using the average moles of vitamin C titrated, calculate the amount of vitamin C, in mg, that was in the
tablet you analyzed. (Hint: Remember how the tablet was prepared and put into solution before titration).

I believe for this I can write:

Avg moles vitamin C * XXXX grams vitamin C / 1 mole vitamin C * 1000mg/1g * 20 (this is a value given to us)

is that correct technique?

Calculate the % composition of vitamin C in the tablet.

Not sure how to do this..

[Borek]

The key reaction of this experiment was :
IO3- + 5I- + 6 H+ -> 3 I2 + 3 H2O

This is one of two key reactions. The other one is the direct reaction between iodine and ascorbic acid.

[Hemidol]

Yup your 100% right. For the very firstquestion, I believe I can write:

10ml * 0.002034M KIO3 * 3 mole KIO3 (from mole-mole ratio) = XXXX mole vit C


correct releshonship?

[jsmith613]

From the volume of titrant added, calculate the moles of vitamin C for each titration. Show a sample
calculation for trial 1. From the results this, calculate the average value for the number of moles of vitamin C titrated. Report the final value to the appropriate number of significant figures.


Given these values:
concentration of KIO3 M:  0.002034
weight of tablet: 0.3g

trial #1:
final buret reading: 20mL
initial buret reading: 30mL
volume of KIO3: 10mL
weight of vitamin C tablet: 5g

trial #2:
final buret reading: 12mL
initial buret reading: 20mL
volume of KIO3: 8mL

The key reaction of this experiment was :
IO3- + 5I- + 6 H+ -> 3 I2 + 3 H2O

how can I do this?? This was an experiment involving identifying the compositon of vitamin C

personally i would use the formula
moles = mass / RFM

moles = 0.3 / 176 (RFM of C₆H₈O₆

moles = 0.0017045454545

[Hemidol]

From the volume of titrant added, calculate the moles of vitamin C for each titration. Show a sample
calculation for trial 1. From the results this, calculate the average value for the number of moles of vitamin C titrated. Report the final value to the appropriate number of significant figures.


Given these values:
concentration of KIO3 M:  0.002034
weight of tablet: 0.3g

trial #1:
final buret reading: 20mL
initial buret reading: 30mL
volume of KIO3: 10mL
weight of vitamin C tablet: 5g

trial #2:
final buret reading: 12mL
initial buret reading: 20mL
volume of KIO3: 8mL

The key reaction of this experiment was :
IO3- + 5I- + 6 H+ -> 3 I2 + 3 H2O

how can I do this?? This was an experiment involving identifying the compositon of vitamin C

personally i would use the formula
moles = mass / RFM

moles = 0.3 / 176 (RFM of C₆H₈O₆

moles = 0.0017045454545

But its requesting to find it from the volume of titrant added.. so you can't do it that way.

[jsmith613]

But its requesting to find it from the volume of titrant added.. so you can't do it that way.

If we knew the vol of KIO₃ used it would be easier, we already know its concentration as you said before (0.002034) therefore if we knew the vol of KIO₃ used we could work out the volume. What volume of KIO₃ was used?

[Hemidol]

But its requesting to find it from the volume of titrant added.. so you can't do it that way.

If we knew the vol of KIO₃ used it would be easier, we already know its concentration as you said before (0.002034) therefore if we knew the vol of KIO₃ used we could work out the volume. What volume of KIO₃ was used?

lol its right there, 8ml and 10ml (in their respective trials)

[jsmith613]

So moles = concentration * vol dm3
10 ml = 0.01 dm3

moles in KIO3 = 0.002034 * 0.01
moles = 0.00002034

(seems strange so i think someone should check it)
then if 1 mole of KIO3 reacts with 1 mole of vitamin C, moles of vitamin C = 0.00002034
if 1 mole of KIO3 reactions with 2 mole then 0.00002034 * 2
etc...