* To download the lab as a file, click here (PDF file); or here (doc file).

Introduction

The ACME Laboratory now would like for your team to test for the total dissolved solids (TDS) in the water source used in the TSS experiment. To insure that the suspended solids are removed from the water source, the team must design a filtering system to remove small particles found in the water.

Discuss among the team members the size and number of samples to be tested. The size and number of samples tested will determine the amount of the water source needed to conduct the experiment.

Before beginning this experiment read the questions in the last section to help determine what is being asked of the lab.

Procedure:

Filter Design: Obtain filter paper, charcoal, sand, funnel, vacuum filtration apparatus, and 250 to 400 mL beaker. Clean all glassware prior to testing with distilled water. This cleaning process is to prevent any contamination from tap water. In designing this filtration system, keep in mind that a combination of the materials can be used. Record any observations on the clarity of the water for each filtration system used in the experiment.

Testing for TDS: Materials needed for this portion of the experiment. The team must decide the sample size to be tested. A combination of sample sizes will work, or the same sample sizes for all the tests conducted will be sufficient. After determining the sample size(s), obtain four beakers that will hold the filtered samples during the test. Be sure to clean the glassware thoroughly with distilled water before conducting the test. Record the initial mass of each beaker prior to conducting the experiment. With a graduated cylinder, measure the sample and place in a beaker. Repeat procedure three times. There should be four samples tested. Then turn the hot plate on and set the four beakers on it. Do not allow the water to boil over. This will result in the loss of dissolved solids. Boil off all the water from the samples. Allow the beakers to cool before measuring the final mass. The results should be in mg/L in your report.

Questions

1. Was there a combination of materials used in the construction of the filter? Why or why not.

2. How was the filter design constructed? Draw a diagram of the filter.

3. Did this design work? How was this conclusion determined?

4. Did water source have a greater TSS or TDS? Is the result what you expected?

5. What do you think were the main contributing ions in the TDS? Would the water samples tested in this experiment be considered hard water? What would be a way to determine that conclusion?