Chem Lab: Acid/Base Titration

This video details how to do the Titration lab.

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Closed Caption:

so you go into the chemical storeroom
and you grab a stock bottle of sodium
hydroxide and you notice there's no
concentration listed on it
oh my goodness what are we going to do
when you run an experiment you kind of
need to know what the concentration of
your uh solution is so what you need to
do is figure out a way to determine what
the concentration of this naoh is now
fortunately it is naoh which makes it a
base so how do you figure out the
concentration of the bases well
neutralize it with an acid his
concentration you know this . 1000 molar
HCl hydrochloric acid
I know because I made it myself it's
good stuff really
so we're going to do is we're going to
neutralize the acid in the base going to
figure out how much basis it take to
neutralize a certain volume of the acid
rain is titration equation number of a
chismosa equal number of all ages mobile
now hydrochloric acid has 1h in the
formula sodium hydroxide has 10 h in the
formula so that's easy enough and we
know the molarity of the acid ma that's
. 100 molar we don't know love though
that's what we're trying to find out
trying to figure out mud so we do is we
find out the volume of acid Bob and
behind the bass club and then just
simply solve for mud we're gonna do this
with a process called titration you see
what happens is when you react acid with
base the hydrogen ion for the acid and
the hydroxide ion from the base combined
form a molecule what
meanwhile the other ions combined form
substance known as assault if number of
moles of hydrogen ions the number of
moles of hydroxide ions are equal
solution is going to neutralize itself
to a nice neutral ph of so this
particular lab trying to find out what
the molarity of the basis to figure that
out
divide both sides by the other stuff
number
no ages love number of wages look since
number of hydrogen's and hydroxides with
the same and just simply cancel out we
don't have to worry about
we know the molarity the acid . 100
molar so all you gotta do is find out
the volume of the acid and falling with
the base that's going to take to
neutralize that acid once you got that
information you just can plug it in and
i'll tell you the molarity of the base
nice and simple except in this lab you
guys are going to do for trials you run
the experiment four times and then
average the full results that will give
us our most accurate results the
equipment you need to make this lab work
or two beakers one labeled a for acid
the other labeled be four base to
acid-base beurettes one of them labeled
a for asset the other one labeled be
four base two funnels one of them
labeled a for acid the other one labeled
be four base a 125 milliliters
erlenmeyer flask a white piece of paper
to improve contrast when you put on the
ring stand and a black piece of paper to
help improve contrast when you read the
numbers off of the burette without the
black piece of paper with the black
piece of paper
look at that incredible difference first
step
measure out 60 milliliters of the acid
and the base making sure to cast the
container after you measure it out make
sure that both valves on your pure ettes
are in the closed position and then
place the burette assembly on the ground
lift the funnel up and then pour in the
acid and base in their respective
beurettes until the level is between
zero and the top
between 0 and the top perfect
the first thing you need to do is get
the air bubbles out of the tips tapout
the air bubbles and continue draining
until the level of the base is at zero
milliliters drain out the acid until you
have exactly 10 milliliters of acid and
now add three drops of phenol failing to
your acid place a white piece of paper
underneath the base BR a place the
acidflask underneath and start adding
your base and then we don't like mixing
stuff right here waiting for it to be
there for 10 seconds now there's still a
higher concentration of acid than base
which is why the thing color disappears
but as you add more bass and the ph
rises closer to neutral the pink color
hangs out a little longer so you had a
little less each time
if you add too much bass you can go back
and clear it up with a drop of acid and
then when you go back to add base again
just use shorter skills maneuvers wait
start it now that you've got it cleared
back up again put it back underneath the
base and just add less base perfect
that was one drama now that you've got
the correct color you know your solution
has been neutralized
so now you're going to use the black
piece of paper and you're going to hold
it up so that you can more easily read
the level of the liquid in the burette
and then record your data for trial one
and this is the perfect shade think that
you should get after titrating now
remember feeling feeling doesn't start
turning color until the ph of 8.2 so
what you have in here is not a neutral
solution but the difference in volume
between a ph of a point to and a pH of 7
is so tiny that it works now that you've
finished your first trial you can take
the flask dump it in the sink then give
it a good rinsing
your final volume of trial
comes the initial volume of trial two
and then you will repeat the process
putting in another fresh 10 milliliters
of acid into the flask so your final
volume was ten points of 10 milliliters
will drain it out until it reads 20 . 10
milliliters and then repeat the process
until you have data for four trials and
the data gradually builds up you'll find
that as you do it more and more your
technique will continue to improve once
you forward the results of your last
trial down the drain
given everything good washing your first
step is to remove the funnels from the
top of the burette and wash it out
next take the beurettes and tilt it down
into the sink to drain it out
opening up the other side to let it flow
more freely then close the valve turn it
right side up open event once more and
add distilled water to the top as you
rotate the burette to clean out all
sides eventually enough pressure will
build up but the water will rinse out
the tip this is especially important
with the base as the base when the water
evaporates will heal will precipitate
out and could seal the tip of the
burette and now we'll do is close the
valve closed the valve and then turn it
upside down and upside down and dump out
the distilled water repeat the process
with the other beurette reinsert the
funnels once both your rights have been
cleaned and then place all equipment
back along the side of the room where
you found
activity like perfect