Titrations with Sodium Thiosulfate

Titrations with Sodium Thiosulfate - Titrations with Sodium...

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Titrations with Sodium Thiosulfate Chem 210 3/17/2011 Kimberly Hargraves
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Hargraves 2 Abstract: Sodium Thiosulfate is a titrant that was used to determine the percentage of copper in pennies. The solution of Sodium Thiosulfate was reacted with Iodide and was reduced, which resulted in a reaction with Copper during titration. The Copper samples were dissolved using 6 M HNO 3 . The average grams of the pure Copper wire samples were divided by grams of the pennies and multiplied to get an average percent. The average amount of copper in each penny is 8.6327%. Introduction: In this lab, a pure sample of Copper was used as a primary standard for sodium thiosulfate. Standardization of Sodium Thiosulfate allows the percentage of Copper to be calculated. This Standardization method can be used to determine the amount of copper in brass samples. Iodimetry was also performed in this lab. Iodimetry is the process of using iodine as the oxidizing agent. Iodine was titrated with sodium thiosulfate solution because an addition of excess iodide ion to the oxidizing agent analyte is produced. 2I - →I 2 + 2e - shows the reducing properties of iodide ion. I 2 +2S 2 O 3 2- →S 4 O 6 2- shows the reaction of iodine reacting with thiosulfate. 2 Cu 2+ + 4 I - ↔ 2 CuI (s) + I 2 and I 2 + 2 S 2 O 3 -2 ↔ 2 I - + S 4 O 6 -2 shows that the ratio is 1:1 since 2 moles of copper requires 2 moles of thiosulfate. 1
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Titrations with Sodium Thiosulfate - Titrations with Sodium...

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