IIT JEE , AIEEE Forum - Chemistry , Physical Chemistry

priyesh

1) Why are substances like Platinium & palladium used for carrying out out electrolysis of aqueous solns?

2) Why is it necessary to remove CO when ammonia is being manufactured by habers process

3) Why is ester hydrolysis slow in the beginning and becomes faster after sometime

4) What modification can u suggest in the hardy Schulze rule

5) Why is it essential to wash the precipitate with water before estimating it quantitatively

Plz answer as fast as u can

kasirajan.1990

i guess the modification might b these :

(i) the ions carrying the charge opposite to that of sol particles are effective in causing coagulation.

(ii) coagulation power of an electrolyte is direclty proportional to the 4th power of the valency of the active ions.

bt instead of usin the 2nd-rule we hv to use the gold num method...
where gold num meanz ts the num of milligrams of gold sol added jus to prevent the coagulation of 10 ml of of 0.1 % NaCl soln.
so as to find the coagulatin power of an electrolyte efficiently.

kasirajan.1990

Pt n Pd are inert electrodes...hence...they r used in electrolysis of aqn soln.

kasirajan.1990

CO is taken out in habers process...as it mite poison the catalyst.

varshavallig

1)they rpovide lage surface area for the reaction to take place and for the movement of electrons.
2)it will poison the catalyst.
!!!!!!!!!!!!!

varshavallig

in the beginning H+ from water catalyses the rxn.but as the rxn proceeds an acid is formed which will also generate H+ ions .so it bcomes faster after sometime.
!!!!!!!!!!

kasirajan.1990

when the conc of the products increases the rxn tends to ..
flow in reverse direction...thts y rate of rxn increases after sumtym.

varshavallig

4) gold no. shud b used and not coagulation no.
5)ppt shud b washed to remove any dust that got adsorbed .if it is not washed ,the weight v measure will b wrong.if washed it will b the correct wt of the ppt.
hope this helps
!!!!!!!!!!!!!!!!!!!!!

neeraj_agarwal_1990

can u explain 4) in detail??

wats this "gold no."??

ramkumar_november

Gold Number of a protective colloid is the minimum amount of in milligrams which must be added to standard red gold sol so that no coagulation takes place when 1 ml of 10%NaCl solution is rapidly added to it...........

lower the gold number , more protective is the colloid.......

modification in hardy schulze law is this ::
" When oppositely charged sols are mixed in proper proportions to neutralize the charge on each other , coagulation of both the sols occur " .......

priyesh

Thanks to all

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