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Unformatted text preview: mine the molar mass
of the acid from this step.
KHP is a monoprotic acid, so the reaction can be simplified as
KHP (aq) + NaOH (aq) à KNaP (aq) + H2 O (l)
Using standard stoichiometric techniques, calculate the molarity of NaOH for each run. Take the
average and determine the standard deviation.
The acid is monoprotic, so again, we can write
HA (aq) + NaOH (aq) à NaA (aq) + H2 O (l)
Use standard stoichiometric techniques to calculate the moles of acid for each run, then, for each
run, divide the mass of the acid by the moles of the acid to determine the molecular mass. Take
the average and determine the standard deviation. Dakota State University page 1 52 of 232 Experiment 13: Molecular Mass of an Acid General Chemistry I and II Lab Manual Observations:
Run Mass KHP Initial
base molarity 1
Average molarit y:
Observations: Dakota State University page 1 53 of 232 Experiment 13: Molecular Mass of an Acid General Chemistry I and II Lab Manual Molecular Mass Determination: Run Mass acid Initial
base moles of
Average molecular mass:
Observations: Dakota State University page 1 54 of 232 Experiment 13: Molecular Mass of an Acid General Chemistry I and II Lab Manual Pre-Lab Questions:
1. What is the primary standard we are using?
2. How closely should runs agree to avoid the fourth run?
3. Why do you have to be particularly careful of the tip of the buret in a titration? Dakota State University page 1 55 of 232 Experiment 13: Molecular Mass of an Acid General Chemistry I and II Lab Manual Post-Lab Questions:
1. What are the major sources of error in this experiment?
2. Do you have a guess as to what the acid might be?
3. (Answer this question if you plotted the titration curve) What is the pKa of the acid? Does
this jive with your guess from question 2? Dakota State University page 1 56 of 232 Experiment 14: Titration of Antacids General Chemistry I and II Lab Manual Experiment 14: Titration of Antacids
Purpose: To understand antacid neutralization power.
Purple: Favorite color of the artist originally known as Prince but then known as the artist
formerly known as “Prince” but currently known as “Prince” once again. Background:
See “Using the Pasco System” and “Basic Laboratory Procedures”; pipettes, burets, balance
There have been a lot of wild claims regarding antacids by the manufacturers; now you
will have your opportunity to test these claims. The goal of today’s experiment is to determine
how much 0.1 M HCl (roughly the molarity of HCl in stomach acid) will be neutralized per gram
of antacid, per dose of antacid, and per dollar of antacid.
Choose three antacids; at least one liquid, at least one solid, and at least one with a
mixture of active ingredients. Be sure to record the name of the antacid, the price, the number of
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