What volume of "base" is required to exactly neutralize
a small volume (10.0 - 15.0 mL) of "acid"?
Hints & Notes
- The reaction is HCl(aq) + NaOH(aq)
--> NaCl(aq) + HOH(l)
- Use a couple of drops of phenolphthalein indicator to
see when the reaction is complete. Aim for the lightest pink that you
are sure is pink.
- Before starting, develop a data table to record all of
- Examine the burets used to dispense the acid and the base.
Burets are labeled to measure volume dispensed, so when they
are full, they read "0.0" (because they haven't dispensed anything).
Be sure to record data from these properly.
- After determining the answer to the "assignment question,"
use the given concentration of base to determine the concentration of acid
for each trial.
- Determine the average concentration of the acid for your group's trials.
- Determine the average deviation of your results. Average Deviation
is the average of how different each meaurement is from the average.
Don't use negative numbers in this calculation. Also, re-read the previous
two sentences many times until they make sense: it's not a difficult calculation.
What To Pass In
One lab report, amazingly perfect, for each group. The report
must be on one piece of paper (front and back is OK).
If it's on two sheets of paper it's a "rough draft" and will be returned
- Title stuff (the usual).
- Purpose. Hint: it's NOT the assignment question.
- Data/Results Table. Each trial gets it's own column,
decimals lined up, proper sig figs, labels, names -- all the good stuff from
any data table. For ease of reading, you may include the concentration
of acid (result) as the last line in the data table.
- Sample Calculation. Clear and complete calculation for the first
- Overall Results: Clearly show the average concentration of the acid from
all of your group's trials. Also, calculate the average deviation
and report that.
- TEN points for the group whose average concentration is
closest to the average concentration obtained from all groups in all chem
- FIVE points for the group in each class whose average is
closest to the class average. This can't be the same group as gets the
ten point bonus, and no bonuspoints will be awarded for second place.
- FIVE points for the group with the smallest average deviation
of all classes.
- THREE points for the group in each class with the smallest
average deviation, except the group that gets the second five point bonus.
Although it is wonderful news that you can work together as groups
to pass this lab in, you can be sure that there will be a short and fairly straightforward
quiz about this lab. Yes, it will be open notes, but remember: you need
to understand what you write, take credit for, and read, in order to be successful
(and not just in chemistry).
[Titration Contest Score Sheet][MHS