As snow melts on mountain peaks, the cold mountain water drips, then trickles, then washes
the sides of the mountain, eroding the stone over which it runs. Some of the eroded stone
in the water and some of it gets broken up, by collision and abrasion, into such small pieces that
become suspended and wash along with the flow of the water.
Today we are going to use the process of filtration and
evaporation to separate first the suspended
particles, then the dissolved solids. We will
record our observations.
Clamp the ring with the holder provided onto a ring stand. Fold the circular piece of filter
it fits into the funnel. Wet the piece of filter paper so that it sticks to the funnel. Place the 150
beaker under the funnel. Examine your sample of river water and write down what you see in the
OBSERVATIONS section below. Shake up your sample of river water and
pour it quickly all at
once into the funnel. Observe what happens to the sample as you filter it. Write your
OBSERVATIONS below in section B) Filtration. When all of the river water
has drained through
the funnel, remove the beaker and place it on a hot plate. Allow all the water to boil away. Again
examine the solid left in the beaker. Write your observations below in the section C) Evaporation.
Analysis: Using the wash bottle, add a small amount of distilled water to
the beaker holding the
residue from evaporation. Swirl the beaker to dissolve the solid material. Using the wash bottle
again, wash the test tube that originally held the river water, several times, until all river water and
residue has been removed. Pour one-third of the water in the beaker into the test tube.
1) Carry out a test for the presence of chloride (use one drop of the silver
A white precipitate indicates the presence of chloride.
2) Pour out the solution in the test tube and wash the test tube with distilled water. Pour
third of the solution in the beaker into the test tube. Carry out a test for sulfate
(use one drop of the
Barium Chloride solution.
A silky white precipitate indicates the presence of sulfate.
A) River water
C) Evaporation (boiling)
The components of river water which I found are:
Each student will need one of each of the following:
50 mL Erlenmeyer flask with about 10 mL of "river water."
150 mL beaker
piece of #1 Whatman filter paper to fit the funnel
small ring to support the funnel
connector piece for ring and ring stand
Each row of lab desks will need one of each of the following:
Hot plate capable of holding 5-150 mL beakers
2 - Wash bottles filled with distilled water
Alconox solution and brush large enough to be able quickly to scrub out a 150 mL beaker.
One set for instructor only:
The following spot test reagents:
Bottles with droppers containing
0.1 M BaCl2
0.1 M AgNO3
Must add carbonate and phosphate tests at some future time.
NOTES for getting started:
Important skills a chemist must learn
Today: separation and analysis
Writing reports: Purpose, procedure, observations, calculations, conclusion.
Today: Purpose, observations, conclusion.