Titration Lab Report

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Lab Report 2 – Titration CHEM1903 – Chemistry 1A (SSP) Michael West (305159240) 1. Experiment 2.2 – Titrimetric determination of the molecular mass of an organic acid Method An unknown organic acid was supplied in solid form. The acid was known to be diprotic and had the reference number 19. Using an analytical balance, 1.5397 g of the acid were weighed out, and made up with deionised water into 250 mL of solution. 25 mL of the acid solution was added to a conical flask with phenolphthalein indicator and titrated against standardized 0.0983 M NaOH solution. Three titrations were performed and the results averaged. The molar mass of the acid was then calculated and compared to a list of given possibilities. Results and Calculations The three titres were 26.30 mL, 26.50 mL and 26.30 mL. The mean titre volume was hence 26.37 mL. The number of moles of NaOH was thus moles. Because the acid was diprotic, reaction stoichiometry dictates that there was one mole of acid for every two moles of NaOH. Accordingly, in 25 mL of the acid solution, there were moles of acid. The molar mass of the acid is then g⋅mol-1. This matches most closely with succinic acid, for which the given molar mass was 118.1 g⋅mol-1. Although this represents a 0.6% discrepancy, the error is small enough to identify the acid as succinic acid with a high degree of certainty, given the possibilities listed. 2. Experiment 2.3 – Determination of the carbon dioxide and hydrogencarbonate contents of soda water by indirect titration Method A known excess of standardised sodium hydroxide was added to a known amount of chilled soda water. The remaining sodium hydroxide after reaction with the soda water was determined by titration against standardised HCl, to two separate endpoints. A fuller description of the method is available in the lab book. Results Define titre A as the volume of HCl added in
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