ensures that the appropriate amount of titrant was added After boiling the

Ensures that the appropriate amount of titrant was

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ensures that the appropriate amount of titrant was added. After boiling, the solution is further titrated to completion. [1] For the sample, 0.1g of soda ash is used and 50ml of boiled distilled water, all of these are added to Erlenmeyer flasks for three trials. Phenolphthalein is added then the solutions are titrated. After the titration of phenolphthalein is complete, Methyl Orange is used and titrated. It is stopped midway similar to what was done earlier. RESULTS AND DISCUSSION A. Standardization of HCl The exact concentration of stored titrant may not be completely accurate. It is necessary to know the exact concentration of the titrant to know the exact concentration of the analyte. A primary standard of Na 2 CO 3 of known 99.9% purity is used. The reaction is as follows. Na 2 CO 3 + 2HCl <-> 2NaCl + H 2 CO 3 A solution with Methyl Orange indicator changes color when all CO 3 2- has been converted to H 2 CO 3 . In the reaction, every two moles of HCl corresponds to a mole of Na 2 CO 3 . Using the known mass of the primary standard, it formula mass, the stoichiometric ratio of HCl and Na 2 CO 3 and the volume of the titrant. The concentration of the titrant can be determined. B. Analysis of Soda Ash The main component in this experiment is Na 2 CO 3 . There are two equations involved in this scenario.
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CO 3 2- + H 2 O <-> HCO 3 - + OH - HCO 3 - + H 2 O <-> H 2 CO 3 + OH - When the solution is titrated with HCl, CO 3 2- is used up and transformed into HCO 3 - , when all that remains is HCO 3 - , the pOH is given by pKb 1 + pKb 2 . Its pH given by 14- pOH is 8.33 which is approximately the point when a solution with drops of phenolphthalein indicator changes from colorless to pink and vice versa. This
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  • Fall '17
  • Sir Jaden Smith

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