Chemistry Practice Problems Acid Base Indicators Practice Problems Solution: Consider the acid-base indicator, HIn, featured be...

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Solution: Consider the acid-base indicator, HIn, featured below: Hln (aq) +   H2O (l) ⇌ In– (aq) + H3O+ (aq)         K a = 1.0 x 10–4 (yellow)                         (red) Which of the following statements regarding this indicator is FALSE? (a) The indicator gradually changes color over a pH range of ~ 3-5. (b) The predominant color of the indicator in its acid range is yellow. (c) At its end point, the indicator will appear orange. (d) When placed in a neutral solution (at 25°C), the indicator will appear red. (e) This indicator is suitable to use in a titration involving a weak acid with a strong base.  

Problem

Consider the acid-base indicator, HIn, featured below:

Hln (aq) +   H2O (l) ⇌ In– (aq) + H3O(aq)         K a = 1.0 x 10–4
(yellow)                         (red)

Which of the following statements regarding this indicator is FALSE?

(a) The indicator gradually changes color over a pH range of ~ 3-5.

(b) The predominant color of the indicator in its acid range is yellow.

(c) At its end point, the indicator will appear orange.

(d) When placed in a neutral solution (at 25°C), the indicator will appear red.

(e) This indicator is suitable to use in a titration involving a weak acid with a strong base.