Lab 26
Date:
Titration of HCl
Purpose
Determine the molarity of HCl using standardized NaOH
Background
HCl (aq) + NaOH (aq)  NaCl (aq) + H2O (l)
?? M
0.1M
10.0 mL
Titrate (dictionary) – to ascertain the quantity of a given constituent by
adding a liquid reagent of known strength and measuring the volume
necessary to convert the constituent through a given reaction.
Titrate (our version) – to determine the concentration of solution by
using a solution with a known concentration.
Experiment 1. Clean a buret with soap and water and then ‘prep’
the buret with about 5 mL of 0.10 M NaOH.
2. Using a funnel, fill the buret to the 0.00 mL mark
with 0.10 M NaOH.
3. Pipet 10.0 mL of the HCl solution into a clean
Erlenmeyer flask. Add 2 drops of phenolphthalein.
4. Titrate the HCl slowly until the pink endpoint.
Record the final volume of NaOH used.
5. Repeat the titration 2 more times.
Analysis
1. Which solution was more concentrated? Explain
how you know.
2. Which solution was the standard in this lab?
3. Calculate the average volume of NaOH that was
used to titrate the HCl; convert this to liters.
4. Calculate the molarity of the HCl
5. Why should the first titration trial be performed
slower than the 2nd or 3rd trials.
Results -
Questions 1. What is the formula for molarity?
2. One liter of 0.1M NaOH contains how many moles?
3. How many liters of 0.1M HCl are required to
neutralize 1 L of 0.1M NaOH?
4. How many mL of 0.1M NaOH are required to
neutralize 100 mL of 0.5M HCl?
5. If 10.0 mL of NaOH reacts with 10.0 mL of HCl,
what can be assumed about their concentrations?