Acids and Bases

The last day of actual class at La Junta High School, and we did probably one of the most educational labs I have ever done.  In order to effectively understand Acids and Bases before the year ended, five of us, with the help of Mr. Ludwig, completed the Acid-Base Titration Lab.

Each solution is either determined as an acid or a base depending on it's pH level. If a solution has a pH level of 0-7 it's an acid. If it has a pH level of 7-14 it's a base. If the pH level remains at 7, it's neutral. An example of this would be water. There is a turning point in which the acid turns immediately to a base, and visa versa.
Looking at the difference between acids and bases:

Acids                                                              Neutral                                           Base
low pH                                                             water                                         high pH
bad?                                                                                                                   good?
H+                                                                                                                     OH-

The determining factor between acids and bases is not only dependent on the pH level but also on the amount of hydrogen and hydroxide in the solution. If there is more hydrogen in the solution the solution is an acid, whereas if there is more hydroxide it is a base.

The Experiment:

Our goal for this experiment was to get our solution to the turning point(equivalency point) where it turns from an acid to a base. We were attempting to graph this point on LoggerPro.

Steps:

1. We placed 10 mL of the HCL solution into the beaker along with 50 mL of water.

2. We placed a stirrer in the beaker and placed it on the magnetic stirrer so that it could stir the entire duration of the experiment.
3. We suspended a pH sensor that was connected to LoggerPro into the water in order to track our results. Also, in order to track the pH levels, Mr. Ludwig dropped in a few drops of pH indicator. We did this so that when the acid turned into a base, we would be able to tell immediately because the indicator would scream pink.

4. Using a 50mL buret filled with 0.1 M NaOH, we careful placed the NaOH solution into the distilled water and HCL solution, tracking the amount and pH level every 2 mL.

(because NaOH is a base and HCL is an acid, the solution in the beaker began as an acid. As we slowly poured NaOH into the solution, it was changing into a base.)

Once the solution turned pink, we knew it was fully transformed into a base.

Graph:

As determined by the graph, our experiment went very well as we did accomplish the "S graph" look. As the points on the graph climb, the acid slowly begins turning into a base as the pH level rises. The few dots on the graph that rise so abruptly are the equivalency points where the acid turns into a base, then slowly levels out as a base.

Through the graph and data we collected we were able to determine the concentration of NaOH in the beginning, an the volume of NaOH moles of NaOH, Moles of HCl, and the Concentration of HCL all at the equivalency point.
Concentration of NaOH at beginning: 0.1 M
Volume of NaOH at equivalency point: 15.51 mL or .01551 L
Moles of NaOH at equivalency point: .001551 mol
Moles of HCl at equivalency point: .001551 mol   (the moles of NaOH and the moles of HCl must be equal at the equivalency point.)
Concentration of HCl at equivalency point: .1551 mol/L (to calculate this, we divided the moles of HCl by .01)



In this lab I learned how easy it is for an acid to turn into a base, especially in this case. It only took a drop for the acid to turn pink(into a base). It was a lot of fun working as a class for this last lab. Each of us had a job to do and in this way we accomplished the lab to Mr. Ludwig's expectations. Success!! (: