Lab 3 – Complex Formation – Determination of Chloride Essay

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Bradley Cadet 3/3/14 Lab 3 – Complex Formation – Determination Of Chloride Introduction: Experimental Procedure: Apparatus: * One 250 mL beaker * Three 150 mL beakers * Paper towels * Three stirrer bars * Weighing balance * 25mL and 10mL pipettes * 50mL graduated cylinder * Magnetic Stirrir Reagents: * NaCl * AgNO3 * K2CrO4 (0.1M) indicator * Unknown chloride salt (labeled) * Deionized Water * Sodium Chloride Hazards: Procedure: For the first part of the procedure, we had to weigh 4.25 grams of silver nitrate (AgNO3) and dissolve it into 250 mL of deionized water. This was done in a cleaned 250mL beaker. Afterwards, we were given an amount of sodium chloride to extract three samples of 0.1000 grams of pure sodium chloride into 3 different cleaned 150 mL beakers. To each beaker that contained the samples of pure sodium chloride, we added 25 mL of deionized water. To dissolve the sodium chloride in the deionized water, we placed a magnetic stirrer into each beaker and placed it on the electric stirrer. Right before titration for each beaker containing the dissolving sodium chloride, we added the indicator - K2CrO4. Afterwards, the titrant was added in dropwise amounts. During titration, the solution changed colors from yellow to white. As the titrant was being added into the solution, there was a noticeable red spot at the point of impact between the solution and the titrant drop. This color, but in a light texture, would be what we needed to watch out for, as we neared the endpoint. The endpoint has been reached the second the solution turns and keeps a stable light-reddish color. A pronounced red color would mean that the solution has been over-titrated. This process would then be repeated for the remaining two samples. Trial | Mass of NaCl (g) | Volume of AgNO3 solution added

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