Acid/Base Titration Lab Procedure/Data Table
AP Chemistry/Langellier
Name
Procedure: Use the members of your lab group to split up the work, if you want to get
done in a timely fashion!
1. Determine the amount of 19M NaOH solution that is needed to make 250 mL of
approximately 0.1M NaOH (This was done as a prelab exercise!). Obtain this
volume of the concentrated NaOH and dilute to 250mL in a 500-mL flask by
adding 250 mL of deionized (DI) water. Mix well by swirling. 19M NaOH is very
concentrated and very caustic. Keep off your skin, clothes, etc. Goggles and
apron are a necessity! This becomes your group’s entire supply of NaOH for the
lab—Do not waste it, dump it, or randomly add water to this flask!
2. Obtain a buret and set up a ringstand with a buret clamp. Using the prepared
NaOH solution, rinse the buret with 3 small (~5mL) portions of NaOH, running
each portion out through the tip of the buret. Carefully fill the buret to just above
the 0.00 mL mark. Discharge a ‘blast’ of NaOH into a waste beaker in order to
remove any air bubble from the tip of the buret. Record the initial volume of
NaOH in your data table.
3. Determine the mass of KHP needed to react with 25 mL of 0.1M NaOH. (Also
done in prelab) Mass out approximately this amount of KHP (±0.1 g), recording
the exact mass in your data table. Using approximately 25 mL of deionized water,
dissolve the KHP in a 250-mL Erlenmeyer flask. Be patient as there will be some
back-up in the line; we only have 2 analytical balances. Be gentle and kind to the
balance!
4. Add 2 drops of phenolphthalein indicator to the flask, and titrate it to a pale pink
endpoint. Record the volume of NaOH in your data table. Record value even if
you feel you’ve ‘overshot’ the endpoint. Your eye alone cannot determine the
goodness of a titration. Record final value and do the math first!
5. Refill the buret, read and record the new initial volume, and repeat steps 3 and 4
with a second KHP sample.
6. Each group member a sample of KHP of unknown mass from Mr. Langellier.
Record the number of the unknown in your data table. Pick the order in which
you’ll do the titration of your unknowns, and take turns titrating your samples,
recording data for your own unknown.
7. All group members should assist each other to get ready for their unknown
titration (refill buret with NaOH, obtain needed DI water, etc.). When all
members have completed their unknown titration, the group may perform a third
standardization titration if desired. Once all titrations are complete, clean up:
Excess NaOH can be poured into the NaOH collection beaker, all titrated
solutions can be poured into the sink. Use soap/a brush to wash your glassware.
The buret can be emptied, rinsed (x2) with tap water, then given a final rinse with
DI water. Leave to drain in buret clamp, upside down with stopcock open.
Standardization
Trial 1
Standardization
Trial 2
Mass KHP (g)
Unknown number
Volume final (mL)
Volume initial (mL)
Volume NaOH used
Notes:
Unknown
Trial
XXXXXXXXX
XXXXXXXXX
XXXXXXXXX