# chemistry

The ionization constant Ka of an indicator HIn is 1.0x10^-6. The color of the nonionized form is red and that of the ionized form is yellow. What is the color of this indicator in a solution whose pH is 4.00?

Thanks!

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1. KHIn = (H^+)(In^-)/(HIn) = 1E-6

Solve for (In^-)/(HIn) = Ka/(H^+) =
1E-6/1E-4 = 1E-2 = 0.01
(HIn)(red) = 100(In^-)(yellow)
So what color is it?
Check my thinking.

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2. would it be orange?

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3. Is it because it is more acidic?

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4. in my text book it says that if the calculated value is less than or equal to 0.1 then the color of the conjugate base (In- in this case) predominates. does this mean that the solution will be yellow then?

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5. Covered under later listings.

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