Lab08 - Dr.O PDF

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Chancey Turner CHEM 1315-038 Lab 08: Disappearing/Reappearing Salts Observations: For this experiment, we tested the reactions between several different solutions. We placed a few drops of each solution in a well plate and then added a few drops of another solution to record the reaction or lack of. BaCl2 BaCl2 Na2CO3

Na2CO3 X

BaCO3 (s)

H2SO4

NaCl

MgSO4

X

X

X

X

X

X

X

X

X

X

X

X

X

Precipitate was formed instantly, Cloudy white in color.

H2SO4

BaSO4 (s) Formed a cloudy

H2O(l)+CO2 (g) X

white precipitate, took a few seconds to form.

NaCl

No Reaction

No Reaction

MgSO4

X BaSO4 (s)

X MgCO3 (s)

Even smaller

Formed a large

Very small amount

amount of white

amount of

of white precipitate

precipitate

precipitate, opaquer

instantly formed.

formed instantly.

white. White precipitate

No Reaction

H2O (l)

NaOH

instantly formed,

X

No Reaction X

No Reaction

No Reaction

X

X

No Reaction X

Mg(OH)2 (s) Small Amount

looked like white

of white

paint in water.

precipitate formed.

Table 1. This table represents the solutions used and mixed for this experiment. The data for each reaction is recorded. The (X) means there was no reaction, or it was not tested. After we completed the first part of the experiment, we put 2.5 mL of BaCl2 in a test tube with 2.5mL of Na2CO3. We repeated this for a total of four test tubes. We also did the same thing with MgSO4 and NaOH. With a total of eight test tubes, one of each compound was put in a beaker of water on a hot plate and heated, the remaining six test tubes were diluted with D.I. water, H2SO4, and NaOH. For each test the reactions were as follows. Heating

Dilution with D.I. Water

Dilution with H2SO4

Dilution with NaOH

BaCl2 + Na2CO3 The precipitate gathered in

MgSO4 + NaOH Less precipitate was formed

the middle of the solution.

but still gathered in the

The precipitate settled in the

middle of the solution. The precipitate was mostly at

bottom of the test tube.

the bottom but still floating

5 pipettes were added, and

throughout. 5 pipettes were added, and

the precipitant settled at the

the precipitant was mostly at

bottom.

the bottom but was

5 pipettes were added, and

throughout as well. 5 pipettes were added, and

the precipitant settled at the

the precipitant was mostly at

bottom.

the bottom but was throughout as well.

Table 1.1 This table shows the dilution of each compound.

Data Analysis: 1. The precipitates were very similar to one another. Most were instantly formed, and all were white. The biggest difference was the opacity of each precipitate. 2. a. The combinations of ions that resulted in a formation of precipitate was barium carbonate, barium sulfate, magnesium carbonate, and magnesium hydroxide. b. Yes, oxide was present. c. The combinations that did not produce a precipitate was water. d. BaCO3, BaSO4, MgCO3, and Mg(OH)2

Discussion: 1. Na2CO3 + BaCl2 BaCO3 + 2NaCl H2SO4 + BaCl2 BaSO4 + 2HCl MgSO4 + Na2CO3 MgCO3 + Na2SO4 NaOH+ MgSO4  Mg(OH)2 + NaSO4 2. While heating the precipitate in the solution, there was no phase changes. All that really happened was the precipitate gathered in the middle of the solution in the test tube. 3. Diluting the precipitate, didn’t have a huge effect on the precipitate beyond making it less solid. It became more jelly like in the solution. 4. For our experiment, the precipitates broke up a little bit and was floating around the test tube, but most of the precipitate had settled at the bottom of the test tube. We probably could’ve added more of a different solution to try and dissolve the precipitates completely, but we didn’t. 5. I am able to tell if these will be soluble by using NAG SAG, PMS and Castro Bear acronyms. a. Will be soluble in water b. Will be soluble in water c. Will be soluble in water References: 1. Shannon, M. A.; et al. Science and technology for water purification in the coming decades. Nature. 2007, 42, 301-310. 2. Hendricks, D. W. Water Treatment Unit Processes: Physical and Chemical; Taylor & Francis Group, LLC: Boca Raton, FL, 2006, pp 1067-1079. 3. American Chemical Society. Why Does Water Dissolve Salt? http://www.middleschoolchemistry.com/multimedia/chapter5/lesson3 (accessed Jan 21, 2016). 4. Feng, D.; Aldrich, C.; Tan, H. Treatment of acid mine water by use of heavy metal precipitation and ion exchange. Miner. Eng. 2000, 13, 6, 623-642....