Molarity Lab Report

The goal of this experiment was to: create a dilute NaCl solution and calculate molarity, molality, and parts per million, experimentally determine the molarity of the same dilute NaCl solution through Mohr chloride precipitation technique, then, evaluate the accuracy by comparing the actual value to the experimental one. The actual molarity was calculated using the average density of three trials, mass of NaCl in solution, and molarity formula to be 0.0140 mol/L, the molality was calculated to be 0.0143, and the PPM was calculated to be 833. The experimental value for molarity, obtained through titration using AgNO3 as a titrant with Ag2CrO4 as an indicator, was averaged over three trials to be .01523 mol/L. Comparing experimental and actual values gave an estimated standard deviation of 0.00032 M with a confidence interval of +0.00079 at 95% and +0.0018 at 99%. The percent error for molarity was 8.8%. The experimentally determined molarity was functionally close to the actual molarity, however, some significant error in accuracy was observed. The amount of precision achieved with reasonable accuracy suggests this experiment could be used in testing salinity of separate bodies of water for comparison. The high % error inaccuracy, however, also suggests this should not be used in comparing minute changes in salinity in a single body of water.

The Mohr chloride titration method determines the chloride content in a solution in order determine molarity.

As the titrant, silver nitrate, is added to the analyte, sodium chloride solution, the Cl- ions bond with Ag+ to form the precipitant silver