A possible source of error could have occurred during the dilution of both HCl acid and NaOH base from a concentration of 1.
0 M to 0.1M. As only the dilution formula was used to determine the amount of water needed for the dilution, the concentrations may not have been exact. This lead to a systematic error because the same concentration was used for all experimental trials causing all values to be off in the same direction (either too high or too low). This area could have been improved by purchasing a known 0.1 M concentration of each substance or using a pH probe to obtain a more accurate concentration. Another systematic error could have occurred during the transfer of substances from one piece of apparatus to another.
For example, when transferring the crushed antacid tablet from the mortar and pestle to the weighing boat to the Erlenmeyer flask, some of the residue did not participate in the reaction as the power was still stuck to the equipment. However, as a systematic error this problem was constant for all trials, varying all the results. This area could have been improved by limiting the amount of transfers and using one piece of apparatus to carry out most of the experiment. A possible random error is that associated with judging when a titration has reached its endpoint. There is a great amount of difficulty involved in determining when the solution has turned the correct shade of pink. This error is significant because extra amounts of the NaOH base could have been added while allowing the solution to remain pink and ultimately changing results.
This variation in judgement could have been reduced by taking an average of the trials or using a pH probe to determine when the equivalence point has been reached. Each antacid was only given two minutes to react with the HCl acid before it was titrated against NaOH. However, since all the antacids have varying neutralizing capacities, dissolving rates etc., not all of them would have had the opportunity to react completely and thus the titration could have taken place before the maximum amount of HCl acid was neutralized. This is another random error and could have been minimized by mixing the antacid and HCl acid solution thoroughly for about 15 minutes before titrating.