Question

For this experiment, you will design part of the procedure yourself. While the instructions for the titration are provided, volumes and masses are not. In your data section, copy over what you figure out here for the procedure (see formatting guidelines). Be sure to show your work for these calculations! 4. The vinegar samples that are provided in this experiment are close to 0.1 M in acetic acid. You will measure out samples with a volumetric pipet. a. What volume will the volumetric pipet dispense? (Remember your significant figures!) b. If you need to do three trials, what total volume of your vinegar sample do you need to have at your bench? c. In order to pipet solutions, you must be certain there is enough so that the pipet is not shoved against the bottom of the beaker, so you will need extra vinegar to be sure you can pipet your three samples. Knowing this, approximately what volume of vinegar should you obtain for use at your bench? d. What size beaker would be appropriate to obtain this sample? (look at your glassware inventory list in the Lab Intro section of the manual for options)

Answer 1

a. Typical class A volumetric pipettes are 10.00 mL or 25.00 mL in volume and can dispense the said volumes of liquids in titrimetric analyses. For most practical purposes, a typical volume of 10.00 mL of the analyte is used in the experiment.

b. A total of three titrations are to be performed using 10.00 mL of vinegar in each trial. Hence, the total volume of vinegar required for the three analyses is (3*10.00) mL = 30.00 mL.

c. It is always recommended to have excess analyte solution so that the bottom of the pipette doesn’t shove against the bottom of the beaker. However, a large excess of the analyte must never be used, since the analyte cannot be returned back to the source due to contamination and hence, a balance must be exercised when taking excess of the analyte. In this case, approx.. 40.00 mL of 0.1 M acetic acid solution should be taken in the beaker and 10.00 mL of the solution must be pipetted out thrice.

d. Since approx. 40.00 mL of acetic acid solution will be used for the three analyses, hence, a 50-mL beaker will suffice to store the solution.