Indicator Question (1 Viewer)

Talia95

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How did you explain why it would work as an indicator?
 
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How did you explain why it would work as an indicator?
pH indicators need to accommodate proton transfers and provide a distinguishable colour change. I put down it would work primarily for weak acids as their equivalence point is somewhere in the 3-7 range. Any thoughts on this?
 

Frie

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Isn't it HInd + H2O <-> Ind- + H3O+

In acid, equilibrium shift to left, so colour would be same as HInd (red i think?)
In acid, use up H3O+, shift to right, Ind- colour (green?)

Neutral in middle, forgot what red + green = tho.

Is this explanation ok?
 

superSAIyan2

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^ thats what i wrote. but didnt talk about neutral since you dont know where the equilibrium position lies normally.

You should mention that its an appropriate indicator since it gives two distinct colours in acidic and basic solutions, thus allowing us to identify them as acids or bases.
 

Locus

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^ thats what i wrote. but didnt talk about neutral since you dont know where the equilibrium position lies normally.

You should mention that its an appropriate indicator since it gives two distinct colours in acidic and basic solutions, thus allowing us to identify them as acids or bases.
sai did u get overestimation or udnerestimatiom
 

nifkeh

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^ thats what i wrote. but didnt talk about neutral since you dont know where the equilibrium position lies normally.

You should mention that its an appropriate indicator since it gives two distinct colours in acidic and basic solutions, thus allowing us to identify them as acids or bases.
I wrote this too because I was thinking of buffers
 

superSAIyan2

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sai did u get overestimation or udnerestimatiom
im quite sure that you overestimate HCl. the actual number of moles of sodium carbonate in the conical flask is less than what you calculate (since you incorrectly rinsed and filled the pipette). hence a lower volume of HCl will be used in the titration and you will get a higher concentration
 

Locus

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im quite sure that you overestimate HCl. the actual number of moles of sodium carbonate in the conical flask is less than what you calculate (since you incorrectly rinsed and filled the pipette). hence a lower volume of HCl will be used in the titration and you will get a higher concentration
Awesome ... changed it to overestimtion after reading it again
 

superSAIyan2

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lol i was stuck on that question so long cos i wasnt bothered to read the steps. I thought the picture of the pipette was the burette for a long time
 

vtx

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Then you talk about Le Chatelier's principle and how colour of solution changes as concentration of hydronium and hydroxide change etc.
It can be used as an indicator since colour change is distinct.
 

Menomaths

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Aaaaaaaaaaaaaaaaaand I just wrote 'he will get a titration calculation error' because blah blah :(
 

superSAIyan2

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Then you talk about Le Chatelier's principle and how colour of solution changes as concentration of hydronium and hydroxide change etc.
It can be used as an indicator since colour change is distinct.
damn should have mentioned LCP. i just said, in acidic solution the Hydronium conc increases, so the equilibrium shifts left to decrease H30+ conc. this increases the concentration of HINd, giving a red colour. Similar thing for basic solutions
 

Queenroot

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Aaaaaaaaaaaaaaaaaand I just wrote 'he will get a titration calculation error' because blah blah :(
Oh yes that question, I wasn't sure how to improve the validity. I thought he should just start again...
 

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