“Ammonia fountain” experiment

How to make a chemical fountain at home

In this amaz­ing ex­per­i­ment, you’ll see how the sol­u­bil­i­ty of am­mo­nia and the pow­er of at­mo­spher­ic pres­sure can be used to make a minia­ture chem­i­cal foun­tain.

Safe­ty pre­cau­tions

Wear a pro­tec­tive mask, gloves and glass­es. The ex­per­i­ment must be car­ried out in a well-ven­ti­lat­ed room. When con­duct­ing ex­per­i­ments with a large amount of am­mo­nia, use a round-bot­tomed flask.

Warn­ing! Only un­der adults su­per­vi­sion.

A sim­i­lar ex­per­i­ment is in­clud­ed in the MEL Chem­istry sub­scrip­tion

Reagents and equip­ment:

  • sodi­um hy­drox­ide (10 g);
  • 25% am­mo­nia so­lu­tion (20 ml);
  • con­ic flask;
  • round-bot­tomed flask;
  • cork with glass pipe;
  • 1% so­lu­tion of thy­molph­thalein;
  • crys­tal­liz­er;
  • wa­ter.

Step-by-step in­struc­tions

Sprin­kle sodi­um hy­drox­ide into the con­ic flask and add the am­mo­nia so­lu­tion. Col­lect the am­mo­nia that forms in the round-bot­tomed flask, turn­ing it up­side down. Seal with the cork with the glass pipe. Keep the flask up­side down. In the crys­tal­liz­er with wa­ter, add drops of the thy­molph­thalein so­lu­tion and stir. Im­merse the end of the glass pipe in the crys­tal­liz­er so a lit­tle wa­ter gets into it.

Close the hole with your fin­ger and turn the flask the right way up. The liq­uid that re­mains in the pipe must get into the flask. You can do this ei­ther by shak­ing it vig­or­ous­ly (but you may ac­ci­den­tal­ly break the flask), or by open­ing the hole a lit­tle. As soon as the drop gets in­side the flask, sink the pipe into the wa­ter and ob­serve the liq­uid turn blue and rise up the pipe.

Pro­cess­es de­scrip­tion

In the re­ac­tion of sodi­um hy­drox­ide with the am­mo­nia so­lu­tion, am­mo­nia gas is re­leased. It is lighter than air, so the flask must be held up­side down to make it fill the flask. It is im­por­tant that the flask is com­plete­ly dry, as am­mo­nia has high sol­u­bil­i­ty in wa­ter. The am­mo­nia dis­solves in the drop of wa­ter that we left there, so the liq­uid is quick­ly sucked in­side. The pres­sure in­side the flask drops and the liq­uid is forced up­wards from the force of at­mos­phere pres­sure.