To observe in chemical reactions and indicate chemical properties of different chemical reactions when subjected to different series of chemical reactions and use the data to suggest the ions present in the unknown sample.
Procedure:
Testing the unknown sample.
Twenty-one different known chemicals were provided together with one unknown sample. The sample we labeled using number one up to twenty-one. Small portions of different 21 one solutions with different concentration was used to fill halfway twenty-one well in the well plate, where each sample was put in the well designated to its number. One drop was added to each of 21 well containing known solution. Color change, cloudiness in was recoded in each well after addition of unknown sample.
One different sample at a time was reacted with other twenty different samples to help in identifying name and formula for the unknown compound. The unknown sample was also passed through the flame test. Small amount of unknown sample was burned using the propane torch and the color of the flame was indicated.
Conductivity of all 21 known and the unknown solution was tested where crocodile clip connected using connecting wire to a box with two bulbs one weak and the other strong bulb was used. Electrodes were rinsed thoroughly using distilled water before dipping them to the next sample. Conductivity of the sample was recorded depending on the bulb brightness.
Observations and results
After addition of unknown solution to 21 different sample the observation on color or precipitate formed was recorded as in the table below.
| Number given to each compound | Compound formula or name | Observations |
| 1 | 0.1M Bal(as) | No color |
| 2 | 1.0M CH3COOH (as) | No color |
| 3 | 0.1M Cu(NO3)2 (as) | No color |
| 4 | 0.1M CuSO4 (as) | No color |
| 5 | 0.5M H2SO4 (as) | No color |
| 6 | 1.0M HCl(as) | No color |
| 7 | 1.0M K2CO3(aq) | Cloudy |
| 8 | 0.1M K2SO4(aq) | No color |
| 9 | 0.1M KI (aq) | No color |
| 10 | 1M NH4OH (aq) | No color |
| 11 | 1.0M Na2CO3(aq) | No color |
| 12 | 0.1M Na2SO4 (aq) | No color |
| 13 | 0.1M NaI (aq) | No color |
| 14 | 0.1M NaOH (aq) | No color |
| 15 | 0.1M Ni(NO3)2(aq) | No color |
| 16 | 0.1M NiSO4 (aq) | No color |
| 17 | 0.1M Zn(NO3)2(aq) | No color |
| 18 | 0.1M ZnCl2 (aq) | No color |
| 19 | 0.1M ZnSO4 (aq) | No color |
| 20 | 1% litmus solution (aq) | Light brown |
| 21 | 0.1% phenolphthalein solution (aq) | No color |
| Flame test | Unknown | Orange greenish |
| Conductivity | Unknown | Weak electrolyte |
Conclusion:
From the lab experiment, we found that our unknown sample reacted with sample seven, which is potassium carbonate, and sample 20, which was litmus solution. The reaction between potassium carbonate and unknown sample resulted to cloudy sample showing the presence of either barium ion or lead ions at low concentration in the unknown sample. The flame test resulted to orange greenish color, which is because of presence of barium ions. Therefore the unknown compound was identified as barium nitrate Ba(NO3)2(aq).
Questions:
1. From the results obtained, we found that solutions that contained higher number of ions to be 1M HCL, 1M K2CO3 and 1M Na2CO3 solutions. We noticed through their conductivity where the bulb light was bright. Therefore, this show that there are many number of free ions presents. In addition, we found that 1% litmus solution, 0.1% phenolphthalein contained no ions since, and the bulb did not light up at all. Therefore, this is an indication of no free electron since these are organic compounds.
2. From the result we obtained, copper sulfate and copper nitrate are two of the strong electrolyte while zinc chloride and barium chloride are two of the weak electrolyte.
3. The following are ionic equation for the copper electrolyte
2CuSO4 (aq)+ H2O (l) → 2Cu (s) + 2H2SO4(aq) +O2(g)
Cathode CU2+(aq) +2e-→Cu(s)
Anode 4OH-(aq) →2H2O(l) +O2(g) + 4e-
4. The following are molecular, ionic and net ionic equation for unknown sample.
Ba(NO3)2(aq)
Ba2+ (aq)+ 2e- →Ba(s)
2NO3-(aq)→2H20 (l) + 2e-
Ba2+(aq)+2NO3-(aq) →Ba(NO3)2(s)