The total volume required to reach the endpoint of a titration required more than the 50 mL total volume of the buret. An initia
l volume of 49.16±0.06 mL was delivered, the buret was refilled, and an additional 1.69±0.04 mL was delivered before the endpoint was reached. The titration of a blank solution without the analyte required 0.33±0.04 mL . Calculate the endpoint volume corrected for the blank and its absolute uncertainty. Note: Significant figures are graded for this problem. To avoid rounding errors, do not round your answers until the very end of your calculations.
In a titration always is necessary to subtract the blank volume to the titrant volume to obtain the real volume of the titrant. Thus in this case, the total endpoint volume is the sum of the initial volume delivered and the second volume delivered, minus the blank volume:
V = (49.16±0.06 mL) + (1.69±0.04 mL) - (0.33±0.04 mL)
V = (49.16 + 1.69 - 0.33) ± (0.06+0.04+0.04) mL
V = 50.52 ± 0.14 mL
It is necessary to consider the sum of the errors too.
