7 replies to this topic

[nightingale]

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 ???

[Vini]

nightingale, on Mar 18 2010, 09:20 PM, said:

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 ???

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???

[nightingale]

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 ...

Edited by nightingale, 18 March 2010 - 08:12 AM.

[Vini]

nightingale, on Mar 18 2010, 09:42 PM, said:

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 ...

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....

[nightingale]

thanks

[Prep!]

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!!!  

Edited by Pradeep Iyer, 19 March 2010 - 03:13 AM.

[mdfenko]

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.

[nightingale]

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