[1800chisaki]

So we titrated tablets containing acetylsalicylic acid in lab
Now i need to fill in this table (see attachment below)

Did i calculate mg per tablet or mg in conical flask with my formula?
Also how do i calculate the other one out of these two?

note: its divided by 2 because 1 mol ASA reacts with 2 mol NaOH

maybe i should also mention that we added 10 mL alcohol in the flask so that the tablet could fall apart properly

[chenbeier]

No Information of the mass of tablet and also the aliquote what is used for titration.

[1800chisaki]

the mass of tablet has not been provided by our teacher so i assume its not needed and its titrated with 0,1 M HCl
this was an "online" lab due to covid-19

[chenbeier]

The first row is given below in your picture. But without mass of tablet the other row cannot calculated.

[1800chisaki]

all thats mentioned in my notes is that at a temprature of 25 degrees celsius
the maximum amount of ASA that can be dissolved in 100 mL water is 0,33 grams

[Borek]

You don't need mass of the tablet to calculate amount of ASA that was determined by titration. However, without knowing what the procedure was, whether you titrated ASA from whole tablet, or just part of it (typical procedure often calls fro dissolving tablet, filling up to some volume - like 100 mL, and titrating aliquots - like 20 mL - measured with pipette), there is no way to say what you calculated.

What is f?

[chenbeier]

f is the factor of the NaOH or HCl.  Normal procedure if titration take place. 0,1 M can be higher or smaller according titration factor.

[1800chisaki]

You don't need mass of the tablet to calculate amount of ASA that was determined by titration. However, without knowing what the procedure was, whether you titrated ASA from whole tablet, or just part of it (typical procedure often calls fro dissolving tablet, filling up to some volume - like 100 mL, and titrating aliquots - like 20 mL - measured with pipette), there is no way to say what you calculated.

What is f?

Place one tablet in a conical flask of at least 250 ml. Then carefully add 20.00 mL of 0.1 M NaOH solution. Seal the conical flask and swirl regularly to disintegrate the tablet. After breaking up the tablet, add 10 mL of alcohol and let the mixture stand for 1 h (swirl regularly to dissolve the tablet). As an indicator you use phenolphthalein (2 to 3 drops). Titrate with 0.1 M HCl solution until the mixture just decolorizes. Write down the number of milliliters of HCl you have consumed. Repeat the above operations 3 times.

this is the procedure, first you had to do a blank titration and then this back titration described above

[chenbeier]

You should titrate 3 times, so it means you have to use an aliqout. This is not mentioned.

[1800chisaki]

thats what i think too but then why did our teacher add two separate coloumns //:

[chenbeier]

If you have the aliquot you get a value and calculated to the whole volume you will have the amount in tablet.

[Borek]

Place one tablet in a conical flask of at least 250 ml. Then carefully add 20.00 mL of 0.1 M NaOH solution. Seal the conical flask and swirl regularly to disintegrate the tablet. After breaking up the tablet, add 10 mL of alcohol and let the mixture stand for 1 h (swirl regularly to dissolve the tablet). As an indicator you use phenolphthalein (2 to 3 drops). Titrate with 0.1 M HCl solution until the mixture just decolorizes. Write down the number of milliliters of HCl you have consumed. Repeat the above operations 3 times.

The way I read it you do whole operation - starting with dissolving the whole tablet - three times (so you titrate whole tablets). But the wording could be better.

[1800chisaki]

in total there were three titrations, each with a whole tablet. sorry if my wording is off, english isnt my first language

[1800chisaki]

If you have the aliquot you get a value and calculated to the whole volume you will have the amount in tablet.

what do you mean by aliquot?

[chenbeier]

A aliquot means you made up one sample let say 100 ml. From this you take then 20 ml and do the analysis.
This value would be in the first row. In the second row you have to calculate by 5 to get the whole amount.

But you saying you used 3 tablets and do titration each of them. Then there will be no difference.