SCIENCE PHOTO LIBRARY SCIENCE PHOTO LIBRARY
End of an endothermic reaction. Solid barium hydroxide and solid ammonium chloride have been mixed in a flask that is sitting on a damp piece of wood. As the two chemicals are mixed an endothermic, or heat-absorbing, reaction takes place and the temperature inside the beaker drops dramatically. The digital thermometer shows the temperature in the flask to be minus 23 degrees Celsius. The experiment started at 21 degrees Celsius. The drop in temperature freezes the water between the flask and wooden block, sticking the two together.
Model release not required. Property release not required.