Reactions Lab

1. Introduction/Background: In this lab we investigated 6 different reactions and determined what types of reactions they were. The different reaction types are
1. Combustion - A rapid combination with oxygen that releases a lot of heat as well as CO2 and water.
2. Synthesis - The combining of two smaller elements or compounds to make larger compounds.
3. Decomposition - The breaking down of larger compounds into smaller elements or compounds.
4. Single Displacement - The replacement of one or more atoms of the same type in a compound with an atom or atoms of a different.
5. Double Displacement - Two compounds exchange an atom or atoms of equal charge, usually metals. (i.e. Ba(NO3)2 and CuSO4 exchanging Cu and Ba)
2. Procedure
1. We obtained three small test tubes.
2. We placed a piece of zinc and about 1/2 ml of CuSO4 solution.
3. In the second test tube we added about 1/2 Ba(NO3)2 solution to about 1/2 of CuSO4 solution.
4. In the third test tube we placed a small piece of magnesium ribbon along with about 1/2 ml of HCl solution.
   
5. Then we lighted a bunsen burner and observed the flame.
6. We then rinsed out the first test tube and put some H2O2 into it. We then heated and observed what happened.
7. After this we added a pinch of MnO2 as a catalyst to the H2)2 solution. We heated it and observed the reaction that followed.
3. Data:

   Reactants	Reactions
   Zinc and Copper Sulfate	The Zinc turns brown as it exchanges places with the copper in the copper sulfate compound. Heat is given off as this single displacement reaction occurs.
   Barium Nitrate and Copper Sulfate	Mixture fizzes up and drops in temperature. Double displacement reaction.
   Magnesium and Hydrochloric acid	Fizzes, turns white, and releases heat and energy. Precipitates sink to the bottom of the test tube. Single displacement.
   Bunsen Burner	Hot and blue flame with occasional orange flames. Combustion reaction
   Hydrogen Peroxide Heated	Boils violently and releases a large amount of oxygen. The mixture remaining is water. Decomposition reaction.
   Hydrogen Peroxide and Manganese Oxide	Boils even more readily and mixture turns black. Double displacement.

4. Data Analysis:
1. Zinc and CuSO4 Zn + CuSO4 --> Cu + ZnCuSO4
2. Barium Nitrate and Copper Sulfate CuSO4 + Ba(NO3)2 --> BaSo4 + Cu(NO3)2
3. Magnesium and HCl Mg + 2HCl --> H2 + MgCl2
4. Propane burning C3H8 + 5O2 --> 4H2O + 3CO2
5. H2O2 heated 2H2O2 --> 2H2O + O2
6. MnO2 and H2O2 MnO2 + 2H2O2 --> MnO2 + 2H2O + O2
5. Results:In doing these experiments and examining the formulas we determined the reaction types
1. Zinc+Copper Sulfate-single displacement
2. Barium Nitrate+Copper Sulfate-double displacement
3. Magnesium+Hydrochloric Acid-single displacement
4. Propane Burning-combustion
5. Hydrogen Peroxide Heated-decomposition
6. Manganese Oxide+Hydrogen Peroxide-decomposition
6. Discussion:
1. In the first reaction zinc replaces copper in copper sulfate because zinc is higher than copper on the activity series.
2. Similarly in the second reaction barium is higher than copper on the activity series.
3. In this reaction magnesium replaces hydrogen which is not a metal but behave similarly to one.
4. Any reaction in which a hydrocarbon rapidly combines with oxygen to produce carbon dioxide and water is a combustion reaction which is how you can identify this.
5. The bonds between the oxygen and hydrogen in hydrogen peroxide is relatively weak which is why when heated it turns to water.
6. This reaction is similar to number 5 but manganese oxide acts as a catalysts and is not changed in the reaction but speeds it up.
7. Conclusion:
1. We concluded that you can determine the type of a reaction not only by observing it but by observing the formula.
2. We also determined the type of reactions. (see results)
   

Model lab

Chemistry

Mitchell and Ben
Period 6, 2/19/10


I. Title: Polarity and Molecular Shape Lab

II. Statement of the Problem:

a. How shape affects polarity.

b. How elements combine to form molecules.

III. Hypothesis:

a. We hypothesize that based on the shape of a molecule we can determine whether or not the
molecule is polar.

IV. Materials:

a. Ball and stick model sets, pencils, paper, molecular shape chart (see fig. 1), and a camera.






fig. 1








V. Procedure:

a. We drew a Lewis structure based on the chemical formula.

b. Using the shape chart we determined the actual molecular shape.

c. We then made a model based on the actual molecular shape and the Lewis structure that we made.

d. Then we proceeded to determine if the molecule could be polar based on the shape of the molecule.

e. We then drew the model and took several pictures of the models.

VI. Results:

a. We took the following pictures.


Water: H2O

(Polar)





C2H4








C3 H8








BF3






SO3-2


(Resonance Structure)




VII. Conclusions:

a. We determined that it is not only the difference in electronegativity difference of the atoms in a compound that makes a compound polar, it is also the shape as is the case with H2O

b. A compound must have two distinctive halves so that one can be positive and the other can be negative.

c. We also determined the angle's between bonding groups and the shapes of all the molecules.

d. We learned that fluorine can cause molecule to have weird shapes due to it's high
electronegativity.

Chemistry

Mitchell

Period 6, 2/4/10

Ben

I. Title: The Paper Chromatography Lab

II. Statement of the Problem:

a. Which solvent would have the best retention time and separate the ink into pigments the best

b. The polarity of the solvents will have a significant effect on the retention time.

III. Hypothesis:

a. We hypothesize that the water will work better than the hexane, isopropyl alcohol, and methanol because water is polar and a smaller molecule than the others.

IV. Materials:

a. H₂O, CH₃OH, C₃H₇OH, and C₆H₁₄

b. In this experiment there are several dangerous chemical so goggles and aprons should be used. Also when using a fume hood one should keep their head away from the chemical and not put their head under the fume hood.

V. Procedure:

a. We filled one well of a 24 well plate with each of the four different solvents all with a similar amount.

b. We then took pieces of paper approx. 8 cm long and bent the paper at a 90 degree angle approx. 1 cm from the end.

c. We put four dots of black ink at the crease and did this with 4 different pieces of paper.

d. Then we put one piece of paper in each of the four well plates and observed as the solvent absorbed through the paper and separated the ink into the different pigments.

e. We then repeated the process only using one solvent (H₂O) and five different colored inks. These colors were orange, yellow, black, red, and green.

f. Again we observed the results.

VI. Results:

a. In the first part of the experiment we observed that water had the best retention time because it carried the colors the farthest.

b. The other solvents ranked as follows

2. CH₃OH

3. C₆H₁₄

4. C₂H₇OH

c. In the second part of the experiment we observed that while black, red, and green separated into different pigments orange and yellow did not. (see fig. 1)

fig. 1

VII. Conclusions:

a. Our hypothesis was supported by this experiment

b. This experiment supported our hypothesis because water carried the ink the farthest and separated it into pigments.

c. Water was the best with methanol being second best and hexane doing only slightly better than the isopropyl alcohol.

d. We also concluded that black, red, and green ink is a mixture of pigments while yellow and orange consisted of only one pigment.

e. This experiment demonstrates how the polarity of the elements compare to one another.

f. A possible error is that we didn’t get the exact same amount of solvent in each well. We also didn’t accurately measure the retention time.