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Posted

So I have calculated everything and everytime i get an answer I always seem to end up having more Riboflavin in the power of the pill (which weighs less at .9647g) than the full non-crushed version of the pill (.9695g). I have been using the equation of (c (mg/L) = mass (mg)/V (L)) and I am plugging in the C value that I obtained which is about 51 ppm and then the two mass values and the volume of the dilution which is 250mL. Any help on seeing what I am doing wrong or what the variable letters mean as I am also confused on that front will be helpful. Thank you.

Posted
  On 3/30/2015 at 1:15 AM, MrFanatic said:

They represent the weight of the pill when in powder form and the weight of the pill in bulk respectively

So the same pill when crushed was a fraction lighter, is that correct?

Posted

Yes that is correct. The question is asking for the concentration of Riboflavin within both the crushed (slightly less weight to it) and the bulk pill (the heavier weight of the two) in two different sets of answers.

Posted (edited)

PPM would indicate a number of molecules, so would you need to know the molecular weight of Riboflavin?

What is it?

 

You would think the concentration should not be altered by the amount of material (weight). Do you agree?

That could be wrong if the amount of material is dissolved in a set amount of solvent.

 

What does C value mean?

Edited by Robittybob1
Posted

The units of ppm are mg/L. The answer to the question is is mg as units, thus this leads me to believe that there will be small amounts of difference between each Riboflavin amount in the two different weights given. And the C value is the concentration of the unknown contained in each of the experiments flask. Its unit is ppm.

Posted
  On 3/30/2015 at 4:48 AM, Robittybob1 said:

PPM would indicate a number of molecules,

In general, only if you are measuring gases, and even then it's because ppm is typically given in v/v.

Posted
  On 3/30/2015 at 5:36 AM, MrFanatic said:

The units of ppm are mg/L. The answer to the question is is mg as units, thus this leads me to believe that there will be small amounts of difference between each Riboflavin amount in the two different weights given. And the C value is the concentration of the unknown contained in each of the experiments flask. Its unit is ppm.

OK 1 ppm = 1 mg/kg.

So if you found the result being 51 ppm or 51 mg/kg what more do you need? Your pill doesn't weigh a kg so you have to bring that down.

  On 3/30/2015 at 5:56 AM, John Cuthber said:

In general, only if you are measuring gases, and even then it's because ppm is typically given in v/v.

OK

Posted

For this instance the units for the ppm is mg/L. The problem is getting rid of the liter unit in the bottom of the equation as..... so what I am trying to do now is stoichiometrically get the mass value of the pill to finish in a mg form. I am using the first mass (changing it to mg) and multiplying it by the first dilution factor which is going to be .250 L t hen taking that value and multiplying it by the second dilution factor which would be .01L/.001L thus cancelling out the L unit from the .250 and leaving the units to being mg * L which I then use the C concentration which is around 51 ppm thus making the units mg*mg and giving me an answer of around 124 mg^2 per tablet which means I am looking for one more mg mesurement to divide out and make the Riboflavin concentration more applicable to an actual Vitamin pill.


Okay I believe I figured it out. Thank you for helping me talk it through.

Posted

They were relatively close at 3.016998283 mg for the powder and 3.032009781 for the pill in bulk. So like i said barely any difference, but still a difference. When the standard error or standard deviation was calculated it caused them to be the same value in the end, which was probably do to the inconsistency in the data that i obtained, but yeah those were the answers.

Posted
  On 3/30/2015 at 7:05 AM, MrFanatic said:

They were relatively close at 3.016998283 mg for the powder and 3.032009781 for the pill in bulk. So like i said barely any difference, but still a difference. When the standard error or standard deviation was calculated it caused them to be the same value in the end, which was probably do to the inconsistency in the data that i obtained, but yeah those were the answers.

Sounds high to me.

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