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Transcript of SCIENCE!
The conductivity of 0.01 g/ml of unknown substance was 1401 μS/cm.
Unknown Compound 401R
We conducted several tests to determine some of the characteristics the unknown exhibited
The flame appeared to be orange at first
We came to the conclusion that our cation was Calcium or Sodium due to the orange red flame given off.
We based this off of the research we did online
The results of the pH test determined that the unknown compound was neutral, as indicated by a yellow color on pH paper
Upon test, the compound MgCl2 was also found to be neutral, with a pH of approximately 7
Although the pH probe indicates the unknown compound and MgCl2 as being slightly basic, there may have been a complication with the calibration of the probe. The pH values are nearly identical however, as were the interpreted values of pH paper results, and this is the important aspect.
Mixed unknown compound with Silver Nitrate, Barium Chloride, and HCl to see if there was a reaction.
If there was a reaction with
-white solid forms indicates Cl anion
-pale yellow solid forms indicates Br anion
-yellow solid forms indicates I anion
Barium Chloride: Sulfate anion
HCl: Carbonate anion
How can it be predicated which anion the unknown substance contains by reacting it with Silver Nitrate, Barium Chloride, and HCl?
Reacted the Unknown with the compounds
-Results: precipitate formed with Silver Nitrate (indication of Cl anion); no reaction with HCl and Barium Chloride
The pH probe determined the pH of the solution to be around 9.5, which indicated that the solution was slightly basic
We tested other substances with the Flame test that was in 10 mL of water
KCl - Periwinkle
CaCl2 - Orange Red
NaCl - Orange Yellow
MgCl2 - Colorless
We found that our cation was Mg.
The conductivity test results for the unknown yielded a value that differed greatly from the value of MgCl2.
The unknown salt completely dissolved a clear substance in water.
Our known salt, Magnesium Chloride, completely dissolved in water as a colorless solution.
Flame Test Cont.
The color of flame was identical to our previous flame tests
Day 3: Anion Test
The unknown compound was determined to be MgCl2 through data gathered from other tests, and its pH was found to be around 8.
Because of this, we tested the pH of our unknown once again, only to find the pH to also be around 8
White precipitate formed with synthesized Magnesium Chloride
Unknown pH Probe Data
Average pH: 8.536
MgCl2 pH Probe Data
Average pH: 8.554
Q: Why do cations produce different colors?
Our data then resembles a variety of pH values between the data of the probe, and the interpretation of the pH paper, what might be the reason behind this?
A: This due to the movement of elections. When its heated, the electrons gain energy. Each of these jumps in energy levels involves a certain amount of energy that is released as light energy and this relates to a particular color.
It doesn't matter! Both values indicate each compound as being strong electrolytes!
To avoid the complications of the pH probe, we tested the pH of the newly synthesized compound (dissolved in water) using the pH strip.
The strip indicated the MgCl2 solution to be neutral, which matches the pH interpretations for the stock and unknown compounds
We were able to dissolve our salt completely in water
Day 3 - Synthesis of MgCl2
Percent Yield: 94%
-complications with pH probe
-product lost when "cleaning" Mg solid for faster reaction
Mg(s) +2HCl(aq) => MgCl2(aq) + H2(g)