Question

In titration experiment, you diluted the HCl given to you and then titrated the samples. What are the possible sources of error in titration of the HCl samples?

Answer 1

1.) The indicator does not change at exactly the equivalence point, which will result in a higher number of moles of the solution in your buret than in your flask. This change will increase your molarity the darker your indicator gets (the farther past the equivalence point). For phenolphthalein, it is a good rule of thumb to have the pink hold for about thirty seconds and then be clear.

2.) Drops could get stuck to the side of the beaker, thus decreasing the number of moles that reach the solution, artificially increasing molarity

3.) Actual molarity of the standardized solution. Especially with one or two sig figs, this could dramatically increase or decrease the molarity depending on actual molarity (ex using .09501M solution as .1M)

Also, human error or equiptment failure are never an acceptable sources of error in the science world, no matter how much you screw up a lab.