Abhishek was working in his chemistry lab. He had three test tubes containing three different solutions P, Q and R. When he added few drops of solution R to the test tube containing solution P, solution P turned pink from colorless. After this he added few drops of solution Q to the test tube containing solution P, it then became colorless again. Explain the observations and identify P, Q and R. [5 MARKS]
Abhishek was working in his chemistry lab. He had three test tubes containing three different solutions P, Q and R. When he added few drops of solution R to the test tube containing solution P, solution P turned pink from colorless. After this he added few drops of solution Q to the test tube containing solution P, it then became colorless again. Explain the observations and identify P, Q and R. [5 MARKS]
Each point: 1 Mark
1. Since the color of solution P changed on adding different solutions to it, it must be an indicator.
2. When solution R was added to solution P, its color changed from colorless to pink this implies that solution P is phenolphthalein and solution R is a basic solution as phenolphthalein becomes pink in basic medium. Since on adding solution Q to solution P, P became colorless again, Q must be an acid, as phenolphthalein remains colorless in acidic medium.
3. So, P=Phenolphthalein
4. Q=Acid
5. R=Base
Each point: 1 Mark
1. Since the color of solution P changed on adding different solutions to it, it must be an indicator.
2. When solution R was added to solution P, its color changed from colorless to pink this implies that solution P is phenolphthalein and solution R is a basic solution as phenolphthalein becomes pink in basic medium. Since on adding solution Q to solution P, P became colorless again, Q must be an acid, as phenolphthalein remains colorless in acidic medium.
3. So, P=Phenolphthalein
4. Q=Acid
5. R=Base
