# Indicator Question (1 Viewer)

#### DiValdez

##### Well-Known Member
lol. it was a basic equation..? ind+h <---> Hind

#### kimjuliana

##### Member
what if you didn't write a double arrow? How many marks would I lose??

#### Locus

##### Member
what if you didn't write a double arrow? How many marks would I lose??
1

#### Talia95

##### New Member
How did you explain why it would work as an indicator?

#### drunkenmonkee37

##### Member
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

##### Wannabe Inventor
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

##### Member
^ 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

##### Member
^ 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

##### Member
^ 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

##### Member
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

##### Member
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

#### Makematics

##### hwpo13
Oops fkd this Q up

#### superSAIyan2

##### Member
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

#### Queenroot

##### I complete the Squar3
Oh fuck didn't draw equilibrium arrows noooo

#### vtx

##### Member
$\bg_white HInd_{(aq)} + H_{2}O_{(l)} \rightleftharpoons Ind^{-}_{(aq)} + H^{3}O^{+}_{(aq)}$

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

##### Exaı̸̸̸̸̸̸̸̸lted Member
Aaaaaaaaaaaaaaaaaand I just wrote 'he will get a titration calculation error' because blah blah

#### superSAIyan2

##### Member
$\bg_white HInd_{(aq)} + H_{2}O_{(l)} \rightleftharpoons Ind^{-}_{(aq)} + H^{3}O^{+}_{(aq)}$

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

#### leesh95

##### Member
FML wrote the equation the other way around crap

#### Queenroot

##### I complete the Squar3
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...