Indicator Question (1 Viewer)

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I wrote that when an acid is present, it will react with the indicator, according to the equation: , and when a base is present, it will react with the indicator, according to the equation: ? Would this be acceptable?
 
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leesh95

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I wrote that when an acid is present, it will react with the indicator, according to the equation: , and when a base is present, it will react with the indicator, according to the equation: ? Would this be acceptable?
This is exactly what I did. Do you get any marks for this
 

superSAIyan2

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that looks good as well. the equation vtx gave is probably best though since its more concisse
 

AnimeX

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Would i get anything if I didnt do equilibrium arrows but I did two seperate equations?
 

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I wrote that when an acid is present, it will react with the indicator, according to the equation: , and when a base is present, it will react with the indicator, according to the equation: ? Would this be acceptable?
Same equation as me for the second one. I didn't write the first.
And i said when an acid is added, it removes OH- ions favouring backwards (turning indicator red) and when base is added, OH- increase and therefore favouring forwards, turning green.
 

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Did anyone write that because it shows different colours in different pH levels then it is suitable to act as an indicator? I didn't and I think that was probably worth 1 mark...
 

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Did anyone write that because it shows different colours in different pH levels then it is suitable to act as an indicator? I didn't and I think that was probably worth 1 mark...
A lot of people would've written that lol
 

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i answered it with what would happen if acid/base would be added and how it would affect the equilibrium due to LCP and how a colour change would occur. Hoping for full marks for that section.
 

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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?
Depends on the indicator.
 

someth1ng

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You need to realise that all indicators have a specific pH range.

General Formula:
HInd+H2O⇌Ind-+H3O+

Indicators work because HInd and Ind- are different colours. Within the pH range of the indicator, both exist in significant quantities and hence, both have colour effects that can be seen - that's why, within a pH range, the colour appears to be a mixture of both. When outside the pH range of the indicator, equilibrium is such that either form of the indicator is significantly more dominant. Typically, a clear colour appears when one form of the indicator is approximately 10 times more concentrated than the other.
 
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RealiseNothing

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Same equation as me for the second one. I didn't write the first.
And i said when an acid is added, it removes OH- ions favouring backwards (turning indicator red) and when base is added, OH- increase and therefore favouring forwards, turning green.
I had exactly this.
 

Makematics

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I did Ind- + H2O <> HInd + OH-

meh
i did the exact same thing :O
how many marks do you reckon we can get? i said that acids would turn the indicator red, and bases would turn it green, and explained why using LCP.
 
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RealiseNothing

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i did the exact same thing :O
how many marks do you reckon we can get? i said that acids would turn the indicator red, and bases would turn it green, and explained why using LCP.
The question said to "write an equation that involves HInd and Ind-"

We could still be right?
 

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