MHS Chemistry
Characterization of Sea Water

Purpose

  1. To determine the % mass of suspended material in a sea water sample.
  2. To determine the density of the sea water sample.
  3. To determine the boiling point of the sea water sample.
  4. To determine the % mass of dissolved material in a sea water sample.
Materials
sea water thermometer
organic glassware kit 50.0 mL pycnometer
filter paper & funnel balance
evaporating dish clay triangle
ring stand Bunsen burner

Procedure
        Parts 3 and 4 may be performed simultaneously to save time.
        Goggles must be worn.

Part 1 - % Mass of Suspended Particles

  1. Record the mass of a clean dry beaker.  Obtain approximately 100 to 150 mL of sea water.  Record the exact mass of the sea water in the beaker.
  2. Write your names on a piece of clean dry filter paper, and record it's mass.
  3. Filter the sea water.  Allow the paper to dry overnight.  Collect the filtrate for parts 2-4.
  4. Record the mass of the filter paper with dried residue.
  5. Determine the mass of suspended matter, and % mass of this in sea water.
Part 2 - Density of Sea Water
  1. Determine the mass of a 50.0 mL pycnometer to the nearest milligram.
  2. Determine the mass of your 50.0 mL pycnometer filled with sea water, to the nearest milligram.  The extra seawater should be saved for part 4.
  3. Determine the density of your sample of sea water.  Use this sea water for part 3.
Part 3 - % Dissolved Matter In Sea Water
  1. Record the mass of a clean dry evaporating dish.
  2. Record the mass of a clean dry watch glass.
  3. Fill the evaporating dish 1/2 full with sea water from your density measurements.  Weigh the evaporating dish with the sea water.
  4. Heat your sample over a Bunsen burner until it is almost gone.  Lower the heat and cover it with the watch glass until completely dry.  When it cools, record the mass of your dry sample in the evaporating dish.  Repeat this step until the mass is constant.
  5. Determine the mass of material remaining in the evaporating dish.  This material used to be dissolved in the sea water.
  6. Determine the mass % of dissolved material in your sample.
Part 4 - Boiling Point of Sea Water
  1. Assemble the reflux apparatus as demonstrated.
  2. Heat the leftover seawater from step 2 to boiling, and continue until the temperature remains constant.  Record this constant temperature.
Part 5 - Clean Up
  1. Clean everything up and leave your bench ready for the next class.
  2. The solids collected may be thrown in the trash.


[Analysis of Sea Water score sheet][MHS Chem page]