Video Transcript
Why should a buret not be clamped
too tightly?
A buret is an important piece of
equipment in a titration experiment. A titration is a quantitative
analysis technique in which a solution with a known concentration is used to
determine the concentration of a second solution. One type of titration experiment
that chemistry students often carry out is an acid–base titration. The procedure of a titration
experiment can be pretty complex and involve many different pieces of scientific
equipment.
The diagram shows some of the
essential equipment used in a titration experiment. A conical or Erlenmeyer flask is
typically used to hold a specific volume of the solution we want to determine the
concentration of, which is known as the analyte. An indicator is added to the
analyte solution to help keep track of the chemical reaction during the
experiment. In an acid–base titration with
strong acids and bases, chemists often use the indicator phenolphthalein.
The buret above the conical flask
is held in place with a buret clamp. Chemists adjust the stopcock of the
buret so the solution of known concentration, called the titrant, can flow from the
buret into the conical flask. The solution in the buret should
continue to be added into the conical flask until the end point of the titration is
reached.
We know we have reached the
endpoint when the indicator has just changed color and does not revert back. If phenolphthalein is used, the
solution will turn faint pink. We can then read the markings on
the buret at eye level to determine how much solution was used to reach the end
point. This measurement is then used to
calculate the concentration of the analyte in the conical flask.
We can see that a buret is an
essential piece of equipment in a titration experiment. The buret clamp and retort stand
ensure that the buret does not move too much during the experiment and make it
easier to read the volume accurately. However, a buret clamp should not
be too tight. Burets are made of glass. And if too much pressure is applied
to the buret, it could crack or break, creating a potentially dangerous situation,
and the results of the experiment could be lost.
Based on our discussion, we now
know that the reason a buret should not be clamped too tightly is to prevent the
glass from cracking or breaking.
