2B40.60 • Density and Buoyancy: Hydrometers in Salt vs. Fresh Water

Photos Show the Demonstration Used by the University of Texas at Austin.

Instructions / Notes:

• One graduated cylinder has 250 ml of normal water.
• The other (designated) graduated cylinder has 250 ml of Saline Solution.
• Hydrometers should be lowered in and allowed to settle.
• Dry hydrometers with paper towel once removed and place back into foam slits immediately.

Concepts Conveyed:

• This demonstration shows the difference of buoyancy in the solutions displayed by the varying resting depths of the hydrometers.

Demo Staff Notes:

• Fill cylinders prior to class (one from tap water, other from solution container).
• Provide paper towel for drying off hydrometers to the professor.
• After class dump out water in tap cylinder, pour saline solution back into container and

  WASH OUT CYLINDER THAT CONTAINED SOLUTION. Dry out both if possible.

• Ensure hydrometers are DRY and safely snug in foam slits.

Instructions for making saline solution:

• Pour 1 Liter of tap water into container.
• On a scale: zero to weight of "baby" beaker (provided in box): 30.6 grams.
• Measure 50 grams of salt (80.6 grams of total weight).
• Pour salt into container.
• Stir until solution is clear.

Last updated on January 23, 2025