Ammonia Fountain    

   Step 1       Step 2       Step 3          

        

Step 1:  Boil [500 mL tap water + 10 mL phenolphthalein indicator solution]  in a Florence flask with a long glass tube (as shown).   Steam should be coming out the top.

Step 2:  Invert flask, inserting tube into graduated cylinder or  beaker of [700 mL tap water  +  10 mL concentrated NH4OH]   (csolution 2).

Step 3:  The pressure in the flask will be lower than the air pressure:  water will be pushed into the flask.

The color change is noted as the phenolphthalein changes from acidic (colorless) to basic (purple). 

 

 Boil Water    Invert Flask    Ammonia Fountain    Ammonia Fountain   Ammonia Fountain    Ammonia Fountain

 

TEACHER NOTES

aSTOCK    phenolphthalein STOCK Solution:  750 mL distilled water  +  0.5 g phenolphthalein
                                                                               (add 6M concentrated HCl dropwise until clear)

bSOLUTION 1    500 mL tap water + 10 mL phenolphthalein STOCK solution

cSOLUTION 2    700 mL tap water  +  10 mL concentrated NH4OH