Equilibrium and indicator equation

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SUMMARY

The equilibrium equation for the indicator is represented as HIn ⇌ H+ + In-. When an alkali, such as NaOH, is introduced, the equilibrium shifts to the right, favoring the formation of H+ ions and In- (the conjugate base). This occurs because the added OH- ions react with H+ ions, reducing their concentration and prompting the equilibrium to adjust in order to restore balance. The coursebook's assertion that the equilibrium moves to the right is correct, as it aligns with Le Chatelier's principle, which states that a system at equilibrium will adjust to counteract changes imposed on it.

PREREQUISITES
  • Understanding of chemical equilibrium concepts
  • Familiarity with Le Chatelier's principle
  • Knowledge of acid-base reactions, specifically the role of conjugate acids and bases
  • Basic chemistry knowledge regarding indicators and their behavior in solutions
NEXT STEPS
  • Study Le Chatelier's principle in detail to understand equilibrium shifts
  • Learn about the behavior of indicators in different pH environments
  • Explore the dissociation constants of weak acids and their conjugate bases
  • Investigate the effects of adding strong bases like NaOH on acid-base equilibria
USEFUL FOR

Chemistry students, educators, and anyone interested in understanding acid-base equilibria and the behavior of indicators in chemical reactions.

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The equation for indicator is:
HIn ⇌H+ + In-
Which reaction (forward or reverse) will be preferred when I increase the Alkali.
According to me, The reverse reaction should be preferred as the reaction will try to minimize the effect of the change. Hence In- (i.e the conjugate base) will be increased as it will react with H+ to form HIn.
But the coursebook says that the position of the equilibrium will move to the right. Kindly explain why is that so?
 

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How would the reverse reaction minimise the effect of the change?
How is [In-] increased by reacting with H+?
 
Not enough information to answer. Alkali what? Alkali salt? Alkali base?
 
haha0p1 said:
The equation for indicator is:
HIn ⇌H+ + In-
Which reaction (forward or reverse) will be preferred when I increase the Alkali.
According to me, The reverse reaction should be preferred as the reaction will try to minimize the effect of the change. Hence In- (i.e the conjugate base) will be increased as it will react with H+ to form HIn.
But the coursebook says that the position of the equilibrium will move to the right. Kindly explain why is that so?
The question should be in the homework section. I think it is a good question, deserving some attention by chemistry teachers. I think when I first met this subject at school I felt confused, the reason being what I saw as ambiguous expressions like "the equilibrium will move to the right" I was thinking of equilibrium as weights on a lever… but never mind.

Help yourself by writing out the equation for the equilibrium constant relating [HIn] to the dissociation products molarities [H+] and [In-]. "Adding alkali" means adding something like NaOH, I.e. essentially adding OH- to the solution, which will react with H+ there, and directly or indirectly with HIn (it matters not which) to do - what? So think again through what will happen – you have got it wrong.

I think it is better to work out your own way of thinking and talking about these things (which you are likely to meet again again) rather than someone else's way of expressing it.
 
I came.across a headline and read some of the article, so I was curious. Scientists discover that gold is a 'reactive metal' by accidentally creating a new material in the lab https://www.earth.com/news/discovery-that-gold-is-reactive-metal-by-creating-gold-hydride-in-lab-experiment/ From SLAC - A SLAC team unexpectedly formed gold hydride in an experiment that could pave the way for studying materials under extreme conditions like those found inside certain planets and stars undergoing...

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