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Monday, March 31, 2014
Wednesday, March 12, 2014
Lab 31: Titration Homework
HOMEWORK Lab 31:
Performing Titration to Find the Concentration of an Unknown Basic Solution
Titration
is one of the oldest techniques in chemistry, dating back to the late 1700’s
when French scientists designed the first biuret. A modern day biuret is like a longer, more
accurate graduated cylinder with a rotating valve on the end. This allows us to measure the volume of a liquid
accurately up to 1/10th of a milliliter while we slowly mix it with
another solution one drop at a time. We
will perform an acid-base titration. Mixing acids and bases together creates a
neutralization reaction, as long as the amount of acid is equal to the amount
of base we should end up with a neutral solution of water and salt. In acid-base titration you mix your two
solutions together until the pH = 7.
This is the endpoint (or equivalence point) of the neutralization
reaction. With an accurate tool to
measure the volume of our solution we can tell the concentration of an unknown
solution of acid or base. In this lab
you will know the molarity of your acid and you will have to use titration to
figure out the concentration of an unknown base.
HW Night 1: Due Friday
Work
through or watch the following online resources on titration and answer the
corresponding questions.
VIDEO 1:
How
do you know when the neutralization reaction has reached endpoint?
What
do you notice about the solution as it gets closer to and eventually reaches
the endpoint?
In
our titration, we will have weak base in our flask and weak acid in our
biuret. We will use phenolphthalein as
our pH indicator. Why is phenolphthalein
a good choice to find the endpoint of this titration?
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