[ssssss]

I just had an idea.Sorry if i got stupid.I think few things are not possible by the current theory of masses and quantity.
1.22/7 moles[or PI] moles of a substance cannot exist because if we change this number to Decimals it will be 3.1428...and so on to infinite digits,where as we know we know that one mole has 6.022..x[10]23 so if we see this number we can conclude that atoms cannot be in fraction hence a contradiction.Similar results on 2/3,1/3 and many more rational number moles.Thus that mean atoms are more sepearable,but we certainly cant have a 0.44 of a atom.
2.Moles of certain non rational numbers like square root of 2,3,5 and many others are not possible due to above contradiction.

I think Mass is an integral of its atom mass which further on masses of their neutron,proton and electrons.

[Mitch]

I agree but using the concept doesn't effect calculations. There is only an error of plus or minus 1 in the 24th decimal place. Well within acceptable limits.

Plus any instrument you use to measure the mass is going to have a error that is greater than that theoritical limit.

[ssssss]

To what decimal place can we calculate mass by means of todays modern technology.I guess atmost with the error of 0.00000000001%.

[movies]

My p. chem. book lists the resting mass of a proton at 1.6726231 +/- 0.0000010 x 10^-27 kg.  They somehow have the mass of an electron listed as well with the same number of decimals but 4 orders of magnitude smaller (the error there is only 0.000054 x 10^-31 kg)

That's more exact than I expected.

I assume by the fact that it refers to them as "resting masses" that quantum mechanics changes these numbers when the particles are in motion, so the error is probably much greater in practice.

All of this has absolutely no effect on regular laboratory chemistry however.  The balance in our lab is only accurate to +/- 0.1 mg!

[Mitch]

The balance in my lab is suppose to be +/- 0.1 mg  

[movies]

I would be surprised if our balance is really as accurate as it's supposed to be.  There are a lot of things that can cause it to drift.  I read a short article once that studied the effect of weighing a flask with a magnetic stir bar in it, with the stir bar in different orientations.  The range of masses was like 20 mg.

And we also have a pretty strong air current in our labs, what with all the fume hoods.  The balance has glass doors on each side, but I don't think they work all that well.

[ssssss]

I would be surprised if our balance is really as accurate as it's supposed to be.  There are a lot of things that can cause it to drift.  I read a short article once that studied the effect of weighing a flask with a magnetic stir bar in it, with the stir bar in different orientations.  The range of masses was like 20 mg.

And we also have a pretty strong air current in our labs, what with all the fume hoods.  The balance has glass doors on each side, but I don't think they work all that well.

Dont you peaple use ELECTRONIC BALANCES?I thought its only our worst labs and chemistry boards where we use these manual balances.

The problem with this balances is that they are really time consuming.

[movies]

Dont you peaple use ELECTRONIC BALANCES?I thought its only our worst labs and chemistry boards where we use these manual balances.

Yes, ours is an electronic balance.  I'm sure they make balances that are much more accurate.  It's pretty standard for experimental chemistry labs to have a balance that is accurate to 0.0001 grams (0.1 mg).

[Mitch]

In the end if you measure the difference in masses it really doesn't matter how far the balance has drifted.

[movies]

Yeah, but with the magnetic stir bar thing the orientation of the stir bar made a big difference, so it would only be the same if you had the orientation precisely the same.  The short story: don't weigh the stir bar.