Thermodynamics- Evaporation as an Endothermic Process

Evaporation as an Endothermic Process

Description: A flask containing acetone is hooked to an aspirator. As the pressure inside the  flask is lowered, the acetone boils and its temperature drops.

Source: Shakhashiri, B.Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry

Year: 1989 Vol: 3  Page: 5

Keywords: Evaporation, Endothermic, Acetone, Boiling, Reduced pressure

Rating:

Hazard: Medium

  • Flammability hazard
  • Eye irritation hazard
  • Central nervous system toxicity hazard
  • Implosion hazard
  • Electric shock hazard

Effectiveness: Average

  • Secondary observations
  • Mild effects are seen by audience
  • Results are observable with guidance
  • Good connection from demo to course material
  • Contrast between systems is noticeable
  • Moderate failure  rate
  • Time to results is medium

Difficulty: Medium

  • Use of toxic substances
  • Demos at non-standard conditions
  • Handling of organic chemicals
  • Experiments where data, recording, or display are necessary
  • Some intermediate steps to results

Safety Precautions:

  • Eye protection required
  • Gloves required
  • Absorbent material on hand
  • Perform in a well-ventilated area
  • ABC fire extinguisher on hand
  • Boiling beads required in flask
  • Use of UL approved three-prong plug and outlet

 

Class: Physical Properties

Division: General, Physical Chemistry