DRAFT: This module has unpublished changes.

Equipment:

  • Beaker, glass, 400-mL
  • Beaker, glass, 250-mL
  • Watch Glass, 100-mm
  • Graduated Cylinder
  • Thermometer, Mercury
  • Ring Stand
  • Buret Stand
  • Clay Triangle
  • Bunsen Burner
  • Hot Plate
  • Mesh Pad
  • Crucible with lid
  • Tongs
  • Hot Plate
  • Dropper
  • Ashless Filter Paper
  • Funnel
  • Wash bottle filled with Deionized Water
  • Unknown Alkali Sulfate
  • 0.5 M Barium Nitrate
  • 0.1 Silver Nitrate
  • 6 M Hydrochloric Acid

 

Methods:

  • Obtained equipment. Measured mass of the unknown substance by difference: 0.518g
  • Added 50 mL of deionized water, then stirred. Added 5 mL of the 6 M hydrochloric acid to the solution. Covered beaker with watch glass.
  • Assembled Buret stand, buret clamp, and thermometer. Set hot plate beneath stand. Placed beaker containing solution on the hot plate, and removed watch glass. Adjusted height of clamp so that the thermometer was suspended within the solution without touching the surfaces of the beaker. Heated the solution until it reached 90º C. Added 0.5 M barium nitrate, one drop at a time. Ensured that it was added in excess, so that all sulfate would be precipitated. Waited, before testing for completeness, by adding more barium nitrate.
  • Heated the solution for 1 hour, removed from hot plate, placed on mesh pad, and allowed the solution to cool to room temperature. Returned beaker to heat, and heated for another hour at 90º C.
  • Poured solution through funnel and ashless filter paper to separate the precipitate from the solution. The solution was drained into a 250-mL glass beaker. Washed the precipitate in the filter paper with deionized water, to wash away any remaining solution. Disposed of the solution and wash within the appropriate container.
  • Assembled Bunsen Burner, ring stand, and clay triangle. Inspected crucible and lid for any defects (henceforth, assume that crucible and lid are together, unless stated otherwise). Measured mass of crucible and lid: 39.21g
  • Heated crucible and lid with Bunsen Burner until glowing. Using tongs, placed crucible on mesh pad, and allowed to cool to room temperature, before measuring mass again: 39.09g
  • Reheated, and re-cooled the crucible, before measuring its mass a third time: 39.09g
  • Placed ashless filter paper (with precipitate) into crucible, before heating it for 30 minutes, with the lid removed. After the filter paper was incinerated, continued heating for 10 more minutes, before placing the crucible on the mesh pad, and allowing it to return to room temperature. Measured the mass of the crucible, lid, and precipitate: 39.95g
  • Disposed of precipitate within the appropriate container. Cleaned crucible and lid, and set them aside to dry. Returned all equipment to its point of origin.

DRAFT: This module has unpublished changes.