Kyle Sang, Reuben Everhart
Acid-Base Titration Lab
Purpose: To determine the concentration of 3 different hydrochloric acids (HCl) by performing a
titration
Observations and Predictions:
● Predicted that solutions would take relatively similar amount of times to change color
● Stir bar stirred much faster than expected
● Color was clearly different and was easy to identify when color change took place
● Large difference between amount of solution needed before color change
Materials and Equipment:
● 1 Buret with 50 mL
● 1 Stopcock
● 1 Beaker
● 1 Hot plate
● 20 mL of solutions A, B, C
● Few drops of indicator
● Titrant (.1 M NaOH)
● 1 Stir Bar
Experimental Procedure:
1. Clamp buret to buret clamp
2. Add titrant to buret until it is between 5 and 0 mL
3. Pour 20 mL of sample solution into a beaker and place stir bar inside
4. Set hot plate to stirring mode and stir using stir bar
5. Add a few drops of indicator while the stir bar stirs
6. Place buret over the solution
7. Let titrant drip into the solution until the analyte turns permanently pink
8. Measure the volume of titrant left in the buret
9. Record results of the experiment
10. Repeat steps 1-9 for each solution (A, B, C)
Data:
Sample of Hydrochloric Acid
Starting volume of .1 M
Sodium Hydroxide (mL)
Final Volume of .1 M Sodium
Hydroxide at Equivalence
Point (mL)
A
8.5
48.8
B
28
49
C
31
48.5
Data Analysis:
1. NCl + NaOH => NaCl + H2O
Nitrogen Chloride + Sodium Oxide => Sodium Chloride + Water
2. Solution A: 48.8mL - 8.5mL = 40.3mL
Solution B: 49mL - 28mL = 21mL
Solution C: 48.5mL - 31mL = 17.5mL
3. Solution A: Ma x 20 mL = 0.1 M x 40.3 mL = 0.2015 M
Solution B: Ma x 20 mL = 0.1 M x 21 mL = 0.105 M
Solution C: Ma x 20 mL = 0.1 M x 17.5 mL = 0.0875 M
Error Analysis:
Sample
Our Values(M)
True Values(M)
Percent Error(%)
A
.2015
.2
.75
B
.099
.1
1
C
.05
.05
0
Our errors were caused by natural margin of error, as well as the setup of the lab and
human error. The setup of the lab required us to stop the solution being dripped once we saw
color, however do to the nature of the lab and human error it made it impossible to have an
exact stopping point. We got lucky with Sample C, but that error mostly accounts for the other
small differences.
Conclusion:
We determined our values for each sample by finding how much needed to be dripped
into each solution before it could get a color change. For solution A we got .2015 M, for solution
B we got .105 M, and for Solution C we got .0875 M. These were all very close to the true
values, with solution C’s even being exactly correct. The percent errors were .75% for A, 1% for
B, and perfect for C. These can be explained by simple human error, the fact that it relied on us
to stop the experiment at the exact correct time.