Hypothesis: I believe that Na+ will definitely be present in the unknown sample because many solutions contain a concentration of Na+ whether it is in a large quantity or a small quantity. However, the presence of Ba2+ and Ca2+ may or may not be present in the unknown sample, depending on which type of sample we obtained.
Planning B
Variables:
- An unknown sample
- A centrifuge machine
- Two small test tubes
- A Nichrome wire
- A Bunsen burner
- A stirring rod
- The following chemicals in drop bottles:
-
6 M HC2H3O2
-
1 M K2CrO4
- 12 M HCl
-
6 M H2SO4
- 6 M HCl
- 0.2 M NaCl
-
15 M NH3
- a notebook to write down observations
Procedure:
In order to test for the presence of Ba1+, Ca1+ and Na1+ take a few grams of the unknown and place it into a test tube, placing eight drops of 6 M acetic acid and a drop of 1 M K2CrO4 so that the anions can be separated to identify if there is any concentration of barium. Stir well with a stirring rod and if any yellow precipitate forms, then barium is present. However, if barium is not present, centrifuge the solution and save the decantate into a separate test tube. Using 15 M NH3, bring the decantate into blue litmus, using litmus paper. If precipitate forms, centrifuge the solution, decant and pour enough 6 M HCl so that the precipitate is dissolved. In order to perform a flame test, use a clean Nichrome wire, dip the wire into the solution, and place the wire into the flames of a Bunsen burner. If a red-orange color appears when first placed in the flames and reappears as a red color, then calcium is present in the solution. If neither barium nor calcium appears to be present in solution, then a test for sodium is to be conducted. Pour out a few grams of the unknown into a new test tube and dissolve it with distilled water. Take a clean Nichrome wire once more and conduct a flame test. If a yellow color appears in the flames, the sodium presence is positive.
Data Collection and Analysis
Conclusion and Evaluation
My hypothesis was partially correct in the fact that there was sodium present in the unknown sample. Sodium is found in usually almost every solution whether they are in large quantities or small quantities. After conducting the experiment and obtaining the data, barium is not present in the unknown, but calcium was. The written molecular equations of each the three cations also indicated whether or not precipitate was going to form. The flame tests were an even better confirmation for the presence of these cations since some cations have the characteristics dependent on color when in flames.
