Solve the following riddles :
(a) I turned red in acidic solution and blue in a basic solution. Who am I?
(b) I turn red in acidic solution and yellow in basic solution. Who am I?
(c) I turn colourless in acidic solution and pink in basic solution. Who am I?
(d) I am found at home and turn bright red when I come in contact with soap. Who am i?
Answers
Answer:
The correct options are
A Phenolphthalein:
Colour in acidic solution: Colourless
Colour in basic solution: Pink
D
Methyl orange:
Colour in acidic solution: Red
Colour in basic solution: Yellow
Theory :
Titration : pH indicator is an auxiliary substance added for physical detection of completion of a titration at its equivalence point. It generally shows colour change on the completion of the titration.
Indicators : Indicators are substances which indicate the end-point of a titration by changing their colour.
Indicators are either weak organic acids or weak organic bases having characteristically different colours in ionised and unionised forms.
Phenolphthalein and Methyl orange both show distinct colours in acidic and basic solutions.
Indicator
color change(acidic to basic solution)
Methyl Orange
(
colorless to pink
)
Phenolphthalein
(
Red to Yellow
)
Phenol Red
(
Yellow to Red )
Bromothymol
(
Orange to Blue
)