Introduction

As snow melts on mountain peaks, the cold mountain water drips, then trickles, then washes down the sides of the mountain, eroding the stone over which it runs. Some of the eroded stone dissolves in the water and some of it gets broken up, by collision and abrasion, into such small pieces that they 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.

Procedure

Clamp the ring with the holder provided onto a ring stand. Fold the circular piece of filter paper so it fits into the funnel. Wet the piece of filter paper so that it sticks to the funnel. Place the 150 mL 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 nitrate solution).

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 another 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.

Report Sheet

PURPOSE:

OBSERVATIONS

A) River water

B) Filtration

C) Evaporation (boiling)

CONCLUSION:

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

plastic funnel

piece of #1 Whatman filter paper to fit the funnel

ring stand

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

6M HNO₃

0.5M (NH₄)₂MoO₄

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

Separation

Analysis

Qualitative

Quantitative

Synthesis

Today: separation and analysis

Writing reports: Purpose, procedure, observations, calculations, conclusion.

Today: Purpose, observations, conclusion.