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Calculations performed on the changes in mass revealed that the experimental mass of the NaCl was 1.464 g. The -1.942% error between the two results was attributed to experimental errors arising from the improper use of the pipets during the transfer of the solution to the evaporating dish for heating.
The results obtained showed that the difference in the masses between the expected and experimental results to be small (-0.029 g), resulting in a relatively small % error of -1.942%. The % error was caused by systematic errors resulting from improper use of the pipet during the transfer on the 25 mL NaCl solution to the evaporating dish. Minute air bubbles might have been sucked together with the NaCl solution, resulting in a reduced amount of NaCl being heated at the end, thus lowering the final mass. The pipet used in the experiment has a precision of uncertainty of ±0.01 mL. therefore the 25 mL taken from the volumetric flask was between 24.99 mL – 25.01 mL. This uncertainty is relatively low, making the pipet’s readings relatively precise, thus reducing the chances of random errors resulting from observational mistakes during the filling up of the pipet.
a. Filling the 100 mL volumetric flask beyond the mark would lead to a lower actual (experimental) molarity. This is because adding more water will make the solution more dilute, thus lowering the molarity.
b. The density of the solution would decrease if the volumetric flask was topped beyond the mark because the density if governed by the formula Density = Mass / Volume1. Therefore, increasing the volume would lead to a subsequent decrease in the density.
a. Having the liquid level in the pipet being below the line would lead to a reduction of the mass of the NaCl obtained after the subsequent heating because the amount of NaCl pipet is less than the required amount.
c. Using the pipet to deliver the NaCl solution to