Why this equilibrium doesn't work? (1 Viewer)

[lepton_index]

Question: the equilibrium is: OCl- (aq) + H2O (l) <---> HOCl(aq) + OH-(aq).
Which reaction condition(s) would favour the formation of HOCl?

Options:
A. Adding H2O
B. Adding HCl
C. Both A and B


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The answer is: adding Cl- but NOT adding water (i.e.: B). I'm wondering why? The net ionic equation for this reaction is: H2O(l) <---> H+ (aq) + OH- (aq). Adding HCl means adding more H+ (aq), thus would move the equilibrium the other way --> should NOT favour the formation of HOCl!

And also, why adding water does NOT affect the equilibrium?

Please help. Thanks.

 

[~*HSC 4 life*~]

Question: the equilibrium is: OCl- (aq) + H2O (l) <---> HOCl(aq) + OH-(aq).
Which reaction condition(s) would favour the formation of HOCl?

Options:
A. Adding H2O
B. Adding HCl
C. Both A and B


-----------------------------------------------
The answer is: adding Cl- but NOT adding water (i.e.: B). I'm wondering why? The net ionic equation for this reaction is: H2O(l) <---> H+ (aq) + OH- (aq). Adding HCl means adding more H+ (aq), thus would move the equilibrium the other way --> should NOT favour the formation of HOCl!

And also, why adding water does NOT affect the equilibrium?

Please help. Thanks.

eh? adding h+ to the system, like you said WOULD favour the formation of HOCl, it would cause the equil to shift the the RHS, because you have OH- to consume it, remember Le Chat principle states that the equil would shift to a side to counteract any burden placed on its system. the addition of h+ would cause it to move and produce more OH- to counteract it, hope it makes more sense :/

 

[mystify]

Question: the equilibrium is: OCl- (aq) + H2O (l) <---> HOCl

And also, why adding water does NOT affect the equilibrium?

Please help. Thanks.

I asked my teacher the same thing a while ago.....he said its because water just makes it aqueous and also because it is a neutral substance (contains equal conc. of hydrogen and hydroxide ions) and hence does not affect the overall concentration. Hope that helps

 

[xiao1985]

why addition of H+ ions will affect the eqlbm hsc4life has already explained...

as for water, i believe it WILL affect the eqlbm... and i believe it WILL push the eqlm to the right...

since the position of eqlbm is dependent on the K value, and K = [hocl] x [oh-] / [ocl-]

addition of water will lower all conc.... that is the ratio wll be lower than the K value, so more ocl- will be pushed to produce hocl and oh...

but then agian, i maybe thinkin too much, this q should be only practicin ur knowledge how addition of water will NOT influced [h2o], since h2o is usually neglected when calculating K value....

 

[~*HSC 4 life*~]

don't freak out lepton, coz the 'k' stuff isn't in the syllabus but it does add to the explanation why, i would've thought the answer was (C) but yeah

 

[xiao1985]

don't freak out lepton, coz the 'k' stuff isn't in the syllabus but it does add to the explanation why, i would've thought the answer was (C) but yeah

uh huh,,.. i say the answer is C too... =S

 

[Xayma]

Well adding HCl as there is water there will cause OH^- ions to be removed (from the reactions with the now dissociated HCl) and form water anyway.

 

[googleplex]

thats a q from a catholic trial

water is in excess in the swimming pool, it will NOT effect equilibrium

 

[Li0n]

This was in our half yearly, as people have said water wouldnt affect the equilibrium.
Answer IS Cl-

 

[xiao1985]

well, maybe i am thinkin too much... but the q is yet arguable as to if adding water will influence the concentration of reactants and hence influence the eqlbm...

but then again... if this is not in industrial, u don't need to think that much into the problem... just note that in calculation of eqlbm position, concentration of water is not considered...

 

[eth]

well, maybe i am thinkin too much... but the q is yet arguable as to if adding water will influence the concentration of reactants and hence influence the eqlbm...

but then again... if this is not in industrial, u don't need to think that much into the problem... just note that in calculation of eqlbm position, concentration of water is not considered...

Now, I may be wrong, but I though water was only excluded if there was excessive amounts, like in a swimming pool. I'm pretty sure you count it if it's like a cup of saturated NaCl sol'n, cos more dissolved if you add more water.

 

[sub]

hey dont u ignore any liquid and solid state substances in equilibrium equations? cos thats what we wer taught...only consider the aqueous and gas state stuff...cos their concentrations can change...or sum such explanation.

 

[helper]

As someone said, it is actually activities not concentrations that are important. Adding water will change the concentrations on both sides but not the relative activities.