when 2 or more ions are present in the despersion medium then ion common to the colloidal particle is adsorbed.

for eg when ferric hydroxide sol is prepared by the hydrolysis of ferric chloride has a positive charge becoz of the preferential adsorption of Fe ³⁺on the surface of the ferric hydroxide particle.

       Fe(OH)₃  + Fe³⁺ ---------------->Fe(OH)₃.Fe³⁺

dear for a process to be unstable we have to check the G values as H is not the sole criteria to define the spontaneous nature of a reaction.

G must be -ve .

Endothermic reactions are the one in which energy is required.

for them H of the reaction is +ve.

eg.

In body, respiration is a process in which energy is required(ie endothermic) and need is fullfilled by conversion of ATP to ADP.

yes dear u can do it your self.

there r certain things that u have to keep in mind.

1) honesty to wards prepration.

2) u have to be a smart learner, rather than collecting so many books u have to finish one book(per subject) at least 4 times.

3) don't let your moral down becoz at times u'll feel things are goin out of your hand.

4) do a bit of physical excersise so that u'll have a good health and good mind.

5) chatt with yours friend and your family so that u'll nt feel stressed.

 

there r lot of egs of students that got good rank in iit without any coaching.

Devendra Kumar shukla

M.sc chemistry delhi university.

This chapter is  new this year bt in metallurgy chemistry ellingham diagram is  important stuff (normally asked in graduation papers) so this is a must thing to do...n u'll surely c this question in this years board paper.

we knw that in case of metals, valence electrons are losely held , it revolves around the core or kernel ( for eg Na⁺ in case of Na) that revolving electron also attracts the adjacent core or kernel by this electron gets sandwiched b/w 2 cores which is nothing bt a mettalic bond.

                                                      

                                               

                                                     

                                                       Na⁺

                                                        :

                                                       Na⁺

 

U can distinguish then frm iodoform test. iodoform test is given by those aldehyde and ketones which contain  methyl ketonic group.

here in your question ethanal contain  methyl ketonic group thats y u'll get yellow ppt of CH₃I(iodoform) bt in propanal u'll not get yellow ppt of iodoform becoz it does not contain  methyl ketonic group.

note:THIS TEST IS ALSO GIVEN BY ALCHOLS ON THE SAME FUNDAMENTAL.

Ur not supposed to remember all the structures...those structures which are gvn in boxes are nt in course.....n if u haven't done any of the structure till now then leave them as that chapter is not of much marks...js do all the ncert questions thats suffice..

Devendra Shukla

M.Sc Chemistry

Delhi University

 

i m giving u the exact reaction that u can also refer from page 406 of arihant.

2CH3CHO + NaOH-------->CH3CH(OH)CH2COH (ALDOL)-----LiAlH4------>CH3CH(OH)CH2CH2(OH)

 

Any other problem sir...

hello,

fst of all make aldol of acetone then go for reduction u w'll get the product as 1,3 butanediol

ha ha ha ha ha fst of all i haven't heard of IF72- the compound is IF7 n its hybridization state is Sp3d3...u can check in jd lee and inorganic chemistry by satya prakash.

n the hybridization state of Cr in dichromate is Sp3 itmeans shape is tetrahedral. that u can check in jdlee page no 788.