Question

In the experiment, you are striving to determine the answer both accurately and precisely. Which of the following types of glassware can record the volume to two decimal places ( that is, are precise to 0.01 mL)

a. beaker

b. erlenmeyer flask

c. buret

d. mohr pipet

e. dropper

f. volumeric pipet

g. volumeric flask

Answer 1

Answer for the above question is buret, the various reasons are discussed below,

When the buret is clean and bubble-free, drain the liquid until the meniscus (the bottom of the curved surface of the liquid) is at or slightly below the 0.00-mL mark. It is not necessary to align the meniscus exactly at the 0.00-mL mark since the difference between the initial and final volumes is the desired measurement. If there is a drop of liquid clinging to the buret tip, remove it by gently touching the tip to a glass surface, such as the edge of the waste beaker or wiping with a Kimwipe. The volume of a drop is about 0.1 mL, the same volume as the buret's graduations.Find the bottom of the meniscus, and read the liquid level in the buret to the nearest 0.01 mL at that point. This will take a little practice. Remember, you are reading from the top down. Record this value as the initial volume. Although it is tricky to "read between the lines," remember that the last digit of a measurement is expected to have some uncertainty! One-fifth (1/5) of a division (0.02 mL) can be reproducibly estimated if the meniscus is between calibration marks, after a little practice.Now dispense the liquid you need. If you are using the buret to measure a set amount of liquid, determine what the final reading should be to obtain that amount. Dispense the liquid slowly into the receiving vessel. Remember, in a clean buret, water will coat the interior walls and drain slowly. After closing the stopcock catch any hanging droplet in the receiving vessel. It is part of the measurement at this point, so do not catch it in the waste container. Wait a few seconds for the meniscus to stabilize, then read and record the final volume to the nearest 0.01 mL. The difference between the initial and final readings is the volume you dispensed. When using a buret, it is easier to work with the exact volume dispensed than to try to dispense an exact volume. Plan your work with this in mind.Although burets are sometimes used as dispensers, they are far more frequently used in procedures called titrations. In a titration, one attempts to determine an equivalence point as exactly as possible. This usually involves the first persistent color change of an indicator. With a little practice, one can dispense fractions of drops (less than 0.1 mL) into the titration vessel, and reproduce results within 0.10 mL or less.