preparation of solutions. - had i got it right ?? (Mar/18/2010 )
i was supposed to dissolve 25g of glucose in 100 ml,
but unfortunately,, i got out of d.H2O ...
when i had already started to dissolve the glucose ...
and i have to wait to the second day to have d.H2O.
so i refrigerated the un-known amount of the solution i have,,
and the second day i added d.H2O to reach 100ml..
- it was somewhat 10 ml - ...
and mixed it verrrry well.
is my preparation REALLY a 25g in 100 ml ???
nightingale on Mar 18 2010, 09:20 PM said:
but unfortunately,, i got out of d.H2O ...
when i had already started to dissolve the glucose ...
and i have to wait to the second day to have d.H2O.
so i refrigerated the un-known amount of the solution i have,,
and the second day i added d.H2O to reach 100ml..
- it was somewhat 10 ml - ...
and mixed it verrrry well.
is my preparation REALLY a 25g in 100 ml ???
hey, I am sorry, but your question is not clear to me.....did the 25g glucose that you took, dissolve in whatever x volume of d.H2O you added the previous day???? even if you made up the volume to 100mL the next day, why are you doubtful about the concentration???
thanx for passing DRN 
sorry for this ... 
am ready for any clarification ...
okay to start answering :-
1- did the glc dissolved ?
yes, it did.
2- mmmm,,, because it was already dissolved in the "X" amount and then i made up the volume to 100 ml.
just a thought ...
nightingale on Mar 18 2010, 09:42 PM said:
sorry for this ...
am ready for any clarification ...
okay to start answering :-
1- did the glc dissolved ?
yes, it did.
2- mmmm,,, because it was already dissolved in the "X" amount and then i made up the volume to 100 ml.
just a thought ...
ok Nightingale, now I get your doubt.....It is ok even if you made up the volume later on.....no problem at all with the concentration....
thanks
i know this comes late but still just adding to it!!!!
it wud be a problem only is u have used up some volume.. then the conc will change... otherwise if its not volatile.. which is not in ur case... even if u adjust the volume after a couple of days it s fine!!!!
But a lesson to learn from here is that be ready with everything before doing the experiment!!!!
i ve faced some serious problems due to this in the regard so taking the liberty!!! 
there is no problem if you were supposed to make 25% w/v glucose (25 gm in 100 ml final volume).
it is a problem if you were supposed to add 25 gm to 100 ml water.
grateful to ur advice Pradeep Iyer
in times i think that no matter how well-prepared you were,,
u have to have such a day ... 
always grateful to you mdfenko, and to your precious notes