Qualification > Sciences
Edexcel CHEMISTRY DOUBTS!!!!
NotAbod:
Why can't aldehyde form hydrogen bond with another aldehyde?
Malak:
--- Quote from: Abod on April 03, 2012, 05:03:19 pm ---Why can't aldehyde form hydrogen bond with another aldehyde?
--- End quote ---
For hydrogen bonding to occur, Hydrogen should be bonded to N, F or O. In aldehydes, there is none of them. There is an oxygen but bonded to Carbon, not hydrogen.
NotAbod:
Oh right. don't know how I forgot about it :(
Thanks ang3l
farhanyen:
Question on recrystallisation
My A2 text book:
-dissolve theimure solid in aminimum of hot solvent
-remove any undissolved impurities by filtering the hot solution through a fluted filter paper using a warmed stemless funnel , into a conical flask.
-allow the solution to cool
-Filter the mixture of the pure solid and the solvent under reduced pressure, using a buchner funnel
Collect the solid on the filter paper and discard the filtrate which contains the soluble impurities
-Wash the solid on the filter paper and leave the solid to dry
-carefully remove the pure solid from the filter paper
Past Paper Question: Organic solids are often purified by recrystallisation.This technique waorks on the basis that...
Answer:the cooled solution is saturated with the desired material but not with the impurities
What i don't understand:My text book says that the desired compound is soluble in the hot solution bot not in the cooled solution . So how can the desired material be saturated in the cool solution?????
Romeesa-Chan:
--- Quote from: farhanyen on April 10, 2012, 02:38:50 pm ---Question on recrystallisation
My A2 text book:
-dissolve theimure solid in aminimum of hot solvent
-remove any undissolved impurities by filtering the hot solution through a fluted filter paper using a warmed stemless funnel , into a conical flask.
-allow the solution to cool
-Filter the mixture of the pure solid and the solvent under reduced pressure, using a buchner funnel
Collect the solid on the filter paper and discard the filtrate which contains the soluble impurities
-Wash the solid on the filter paper and leave the solid to dry
-carefully remove the pure solid from the filter paper
Past Paper Question: Organic solids are often purified by recrystallisation.This technique waorks on the basis that...
Answer:the cooled solution is saturated with the desired material but not with the impurities
What i don't understand:My text book says that the desired compound is soluble in the hot solution bot not in the cooled solution . So how can the desired material be saturated in the cool solution?????
--- End quote ---
Read the 2nd and 3rd point of the textbook again.
-remove any undissolved impurities by filtering the hot solution through a fluted filter paper using a warmed stemless funnel , into a conical flask.
-allow the solution to cool
Hope it's clear now.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version