the ionization constant, Ka, for and indicator, HIn, is 1.0x10^-8. The color of the unionized form is red and the color of the ionized form is yellow. What is the color of the indicator in a solution whose pH is 4.6? (Hint: the color of an indicator can be estimated by considering the ratio of [HIn]/[In]. If the ratio is equal to or greater than 10, the color will bet hat of the unionized form. If the ratio is equal to or smaller than 0.1, the color will be that of the ionized form.

Question

the ionization constant, Ka, for and indicator, HIn, is 1.0x10^-8.  The color of the unionized form is red and the color of the ionized form is yellow.  What is the color of the indicator in a solution whose pH is 4.6? (Hint: the color of an indicator can be estimated by considering the ratio of [HIn]/[In].  If the ratio is equal to or greater than 10, the color will bet hat of the unionized form.  If the ratio is equal to or smaller than 0.1, the color will be that of the ionized form.

anonymous · Answer

Ka=[H+][A-]/[HA]
substitute for pH and find the value of A-/HA.

anonymous · Answer

so it'd just be 1x10^-8 divided by 4.6?

anonymous · Answer

pH=4.6
-log H+=4.6
H+=antilog(-4.6)

anonymous · Answer

okay then what?

anonymous · Answer

So you know H+ concentration then find A-/HA and follow whats written in the hint

anonymous · Answer

okay so .0004 is the ratio so it's yellow

anonymous · Answer

Yeah.

anonymous · Answer

awesome thank you so much!