HIn pKa 3.00 7.00% In^- color change pH

HIn pKa 3.00 7.00% In^- color change pH

 

 

어떤 지시약 HIn의 pKa = 3.00

색깔 변화는 지시약의 7.00%가 In^-로 변할 때 나타난다.

색깔 변화가 나타날 때 pH는?

 

 

A certain indicator HIn has a pKa of 3.00

and a color change becomes visible

when 7.00% of the indicator has been converted to In^-.

At what pH is this color change visible?

 

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HA(aq) ⇌ H^+(aq) + A^-(aq)

 

HIn(aq) ⇌ H^+(aq) + In^-(aq)

 

 

 

Henderson-Hasselbalch 일반식

pH = pKa + log([짝염기]/[약산])

pH = pKa + log([A^-] / [HA])

( 참고 https://ywpop.tistory.com/1926 )

 

pH = pKa + log([In^-] / [HIn])

= 3.00 + log(7 / 93)

= 1.8766

 

 

 

답: pH = 1.88