Amounts of reactants and products in a reaction are commonly investigated in two ways in the lab, gravimetrically (by mass), and volumetrically (by volume and concentration). Titration is the name we give to the process used to determine the volume of a given solution needed to react with a given mass or volume of a sample. We will use the quantitatively study a neutralization reaction, in a neutralization reaction an acid and base are combined to produce a salt water. Phenolphthalein will be used as the indicator in this experiment. This indicator is clear in the acidic solution, dark purple or pink in the basic solution and light pink in the solution that has reached its equivalence point. This is the point when the number of moles of acid equal the number of moles of base.
1.Obtain two burettes. Clean and rinse both with distilled water. Each burette is labeled acid or base. Rinse the burette labeled acid with a few ml of HCl and allow to drain into the sink with ample water. Now fill the burette with about 40ml of the HCl. Repeat the rinsing and filling procedure with the base using the NaOH of unknown molarity in the burette labeled base.
2.Record the volume in each burette by reading the bottom of each meniscus to the nearest .01ml.
3.Add 15ml of acid to a 250ml Erlenmeyer flask, then add 3 drops of phenolphthalein to the flask.
4.Holding the neck of the Erlenmeyer flask with one hand and manipulating the burette with the other add some base and gently swirl the flask so the solution will mix. Continue adding base until the first faint pink color develops. If the pink disappears upon mixing the solution add more base drop by drop until pink color persists for at least 10 seconds.
5.Once the equivalence point has been reached record the volume in each burette again by reading the bottom of each materials.
6.Rinse the contents of the Erlenmeyer flask down the drain and rinse the flask with distilled water. Refill the burettes with the proper solutios.
8.After completing all three trials and collecting the necessary data clean up the lab as directed by your instructor.
Trial #3 22.8ml33.7ml15ml
A. #1= (.20)(.0113)= Molarity 2.26
B. #2 =(.20)(.0105)=Molarity 2.1
C.#3=(.20)(.0109)= Molarity 2.18
15-11.3x 100 = 24% Error
15-10.5 x 100 = 30% Error
15-10.9 x 100 = 27% Error
Balanced Chemical Equation
HCl + NaOH ? H2O + NaCl
When pouring the last amount of base right before it turned pink accidentally a lot was poured so it might have had too much. The base also over flowed and poured out all over the place. The bottom part of the meniscus fell out so the results might have been a little off.
There wasn’t a lot of error compared to how many problems occurred. The acid and based diluted causing neutralization. Because of the neutralization a color change occurred. The results of the titration were similar, meaning that the experiment conducted was correct all three times. The molarity found in the observation were around the same also. Therefore the experiment worked as planned and the titration of the acid and bases became neutralized.