4D50.42 - Cloud Formation

Code Number:
Demo Title:
Cloud Formation
Atmospheric Scattering/Condensation
Area of Study:
Plexiglas Box with Hinged Lid, Test Tube and Stopper, 50 ml Beaker with watch glass cover, HCl (Hydrochloric Acid), NH4OH (Ammonium Hydroxide), Black Backstop.

 See also 8A70.45 in Astronomy.

Fill the beaker about 1/2 full of hydrochloric acid and cover with the watch glass.  Fill the test tube 1/2 full of ammonium hydroxide and lightly stopper.  Place the two vessels into the Plexiglas box on opposite sides.  Leave the box open until ready to demonstrate.  Place the TV camera so that it is looking through the box at the black backstop.  When ready to demonstrate uncover the HCl and un-stopper the NH4OH and close the box.  Cloud formation will be observed almost immediately and cloud density will increase with time.  After about 5 to 10 minutes the cloud will be dense enough to completely obscure the backstop.  Products of the reaction are NH4Cl (Ammonium Chloride) and H2O (Water) Spills of both the chemicals should be treated by flushing with water.

  • Elder F. Tubbs, "Demonstration of Gaseous Diffusion", AJP, Vol. 35, # 11, Nov. 1967, p. 1026.
  • Richard J. Fitzgerald, "Derecho Looming", Physics Today, Aug. 2012, p. 72.
  • David Kutliroff, "Gaseous Diffusion and Mobility Dependence on Mass", 101 Classroom Demonstrations and Experiments for Teaching Physics, p. 144.
  • Alex Hutchinson, "Haboob", Popular Mechanics, April 2013, p. 16. 
  • Janice VanCleave, "Determine How the Rate of Diffusion of a Material is Affected by the Shape of the Container It's In", Super Science Challenges, p. 65.

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