wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

Phenolphthalein indicator is used in the pH range


A

3.2-4.4

No worries! We‘ve got your back. Try BYJU‘S free classes today!
B

4.8-6.0

No worries! We‘ve got your back. Try BYJU‘S free classes today!
C

6.8-8.4

No worries! We‘ve got your back. Try BYJU‘S free classes today!
D

8.2-10.0

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
Open in App
Solution

The correct option is D

8.2-10.0


Explanation of the correct option:

Option (D): 8.2-10.0

  • Phenolphthalein is an organic compound with a chemical formula C20H14O4
  • It is used as an indicator to distinguish between acidic and basic mediums.
  • It works only in a basic medium because in the acidic medium it remains colorless.
  • It Changes its color to pink in a basic solution of pH greater than 8.5
  • As the pH increases more than 9 the color of the solution changes from pink to deep red.
  • At room temperature (25°C) the range of pH for phenolphthalein is 8-10.
  • As temperature increases the pH range of phenolphthalein decreases because pKin decreases with an increase in temperature.
  • In an acidic solution, it remains colorless so we cannot use it in the acid test.
  • From the given option only option D has the pH range of the basic medium.

The explanation for the incorrect options:

Option(A): 3.2-4.4

The given pH range is of the acidic medium in which phenolphthalein remains colorless

Option (B): 4.8-6.0

The given pH range is of the acidic medium in which phenolphthalein remains colorless

Option(C): 6.8-8.4

  • The given pH range is not entirely basic as the pH from 6.8 to 7 will be acidic so phenolphthalein will remain colorless in this range.
  • And the change of color in the basic medium can only be observed at a pH greater than 8.5

So, Option (D) is correct.


flag
Suggest Corrections
thumbs-up
2
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Solutions
CHEMISTRY
Watch in App
Join BYJU'S Learning Program
CrossIcon