Edexcel CHEMISTRY DOUBTS!!!!

[MKh]

^Ohhk according to what I know, an acid-base reaction is any reaction between an acid and a base, for example, a neutralisaion reaction in which an acid and a base 'destroy' each other.

To understand a ligand exchange reaction, u will have to understand what a ligand actually is.

[The Golden Girl =D]

Anyone ? ..I got a Quiz on Tuesday so need the answer before it =/

[Romeesa-Chan]

^ I believe it is  violet solution ..according to my chemistry knowledge *poker face*

Ladies and gentlemen can someone clear my doubt , got a test tomorrow -.-

Can someone state what a ligand exchange is and what an acid-base reaction is , what is the difference between them because I'm confused =/


Thanks (:

Ligand exchange reaction - is a reaction in which one ligand in a complex ion is replaced by a different one.

http://www.chemguide.co.uk/inorganic/complexions/ligandexch.html

Acid-Base reaction - is when the acid and base molecules destroy each other when mixed in the right proportions [neutralisation reaction].

[The Golden Girl =D]

Thanks hun

[mandy12]

Can someone give me the revision for unit6b paper? i really don't know how to revise for that..

[MKh]

Can someone give me the revision for unit6b paper? i really don't know how to revise for that..

The Chemistry laboratory skills II exam consists of 3 sections: qualitative analysis (identfying unknown compounds), quantitative analysis (calculations, graphs etc.) and Preparation (explaining the steps in a given experimental procedure for carrying out a preparation) of organic and inorganic compounds.

Check the Practical Assessment section in the Edexcel A2 Chemistry Revision Guide which is available for download in SF.
You will find very helpful information in that section. From the Revison Guide, I quote:

Qualitative analysis
Chemical reactions and tests that may be included in this section include:
- Any of those listed for Unit 3 (therefore you will also have to check the qualilative analysis section the Edexcel AS Chemistry Revision Guide)
- The reactions of the transition metal ions in solution with aqueous sodium hydroxide and with aqueous ammonia both added untl in excess (see pg 81 of guide)
- Ligand exchange reactions in copper (II) complexes (pg 79 of guide)
- The redox chemistry of chromium (pg 78 of guide)

[And the list goes on. It is better if you check the Guide itself]

Quantitative analysis
At least one of the following will be included in this assessment:
- pH titration
- Following the rate of a reaction
- Potassium manganate (VII) titration
- Finding the activation energy of a reaction

Preparation
Laboratory practices needed for preparation:
- Those developed at AS, such as heating under reflux and distillation
- Purification of an impure solid product by recrystallization from hot, saturated solvent
- Melting temperature determination
- Drying solid by filtration under reduced pressure - using a Buchner funnel and flask

Do make sure that you know how to draw labelled diagrams for the apparatus used to carry out distillation, reflux, filtration under reduced pressure and the ones used to determine melting and boiling temperature of a compound

Hope this helps.

[SZM]

Hello guys,

can you tel me what is the difference between IN TERMS OF STRUCTURE AND BONDING in Iron (II) Chloride and Iron (III) chloride???

Please explain me clearly along with diagram...

Thanx in advance.

[SZM]

hello guys, why no reply to my previous post?? Pls i need the answer for that immediately////

[Romeesa-Chan]

Hello guys,

can you tel me what is the difference between IN TERMS OF STRUCTURE AND BONDING in Iron (II) Chloride and Iron (III) chloride???

Please explain me clearly along with diagram...

Thanx in advance.

The question is clear itself.

It asks to differentiate Iron Chloride (II) and Iron Chloride (III) in terms of their bonding and the structure of the molecule.

[SZM]

The question is clear itself.

It asks to differentiate Iron Chloride (II) and Iron Chloride (III) in terms of their bonding and the structure of the molecule.

Sister Romeesa,

I want the answer for the difference between Iron (111) chloride and Iron (11) chloride??? i want the answer// So to explain this answer, pls ur answer shuld be in terms of their structure and bonding....

Hope u got my point. IN SHAA ALLAH.

Waiting 4 ur reply. Wasalaam.

[NotAbod]

Why can't aldehyde form hydrogen bond with another aldehyde?

[Malak]

Why can't aldehyde form hydrogen bond with another aldehyde?

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]

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??

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.