Water Project Report

Water Project Report

Purpose

To determine how ion concentration differs between several east coast rivers sources. Samples were taken from Severn, Magothy and Schuylkill Rivers.

Procedure

EDTA Titrations

EDTA stock solution of approximately 0.01 M concentration was prepared using 0.930 grams of EDTA sodium salt (FW: 372.244 g/mol) and diluting to the 250 mL mark in a volumetric flask. This gave an actual concentration of 0.00999 mol EDTA/L.

A buret was rinsed with the solution and filled to the zero mark. Then 20.00 mL of water from the Severn River was placed in a beaker and treated with five drops of Eriochrome Black T indicator and 10.00 mL pH 10 buffer solution. A stirbar was added to the water sample, and the beaker was placed on a hotplate stirrer, which was switched on before beginning the titration.

The EDTA solution was slowly added to the sample until a color change (from pale magenta to light gray-blue) was observed. The volume of titrant required to achieve the color change was recorded.

The titration procedure was repeated for each water source until there was internal agreement in the results. A total of three trials were performed for the Severn River sample, two for the Magothy River sample, and four for the Schuylkill River. For the latter three trials using Schuylkill River water, the sample size was adjusted to 40.00 mL to allow for greater accuracy and precision in titration.

Conductivity Tests

A conductivity probe was connected to a computer running LoggerPro. The probe was set to the 0-2000 scale and then calibrated using a “sea water” standard NaCl solution. Units were changed to parts per million. Deionized water was also tested for conductivity. Then about 20 mL of each sample was placed in a separate beaker. The conductivity probe, which was rinsed with D-I water between each test, was submerged in each sample. The reading was allowed to stabilize before being recorded for each sample.

Flame Tests

A Bunsen burner...