Question

An acid-base indicator is blue at a ph above 8 and yellow at a ph below 6.1. which form of the indicator would be in greater amount if the solution were blue?

a. cannot be determined from the information given
b. [in-]
c. h[in-]
d. h2o

Answer 1

b. If the indicator is in a basic solution (pH 8) then there are fewer indicator molecules with hydrogens on them

Answer 2

The right answer is B.

The basic medium is a medium poor in H + and rich in OH-, so once the color indicator is put in this medium, it will lose its hydrogen to compensate for the deficit of H + in the medium, so the indicator will take the form In- .

HIn + OH- ==> H +, OH- + In-