Tuesday, May 18, 2010

The Magical Transformation of Aluminum to Copper... Just use Blue Water (Simplified)




Indroduction:


Chemical reactions are so much fun to experiment with. Especially watching the results that occur. The type of reaction that I would like to talk about is a single displacement reaction. This is where one element takes the place of another element in a compound. Ex AB+C --> AC+B. In our Experiment we used the equation Cu(SO4) (copper sulfate)+Al (aluminum --> Al(SO4) (aluminum sulfate)+Cu (Copper). So basically we mixed the Aluminum metal with a diluted Copper sulfate. And when we strained it. It ended up as a diluted Aluminum Sulfate and Copper metal. It was so cool. It was like BOOM... Copper out of Aluminum. Kind of like Jesus turned water into Wine but less epic.

3CuSO4 + 2Al --> Al2(SO4)3 + 3Cu

But this experiment is more than just fancy chemical reactions and all that jazz. We also did this for a learning experience, (though some people probably didn't actually learn that much most likely).

When the Aluminum is mixed with the diluted Copper Sulfate, the Aluminum takes the place of the Copper in the Copper Sulfate, making Aluminum Sulfate. This is because the Aluminum has a higher reactivity than the Copper, allowing the Aluminum to be like "Hey, I'm bigger than you. Get out of the way!!! (seductive voice) Hey Sulfate, hows it going. *wink wink*."




Purpose:

To determine the number of grams of copper that will be produced from an oxidation reduction reaction when you know the mass of Aluminum that reacted with a known amount of Copper(II) Sulfate Pentahydrate and to compare this to the actual yield of copper.

Materials:
  • Safety gear (apron and goggles)

  • 75-100 mL beaker

  • 0.4-0.7 g Aluminum
  • 7-10 g Copper(II) Sulfate Pentahydrate
  • Bunsen burner

  • stirring rod

  • Erlenmeyer flask

  • filter paper

  • glass funnel
















NOOOOOOOOO!!!!!
NOOOOOOOOOOO!!!!!!
NO NO!!!! GOD NO!!!!!
STOOOOOOOPPPPPPPPPPP!!!!!!!!!!

Before you do anything.... you need your safety materials.
Goggles and an Apron
Or else something bad might happen and you could DIE!!!!
Ok... maybe you won't die... but it can still be dangerous.
SO BEWARE!!!! and Be Safe!!!



Now... when you get your Safety Materials... You can Continue.

*Sigh of Relief*













Copper Sulfate




Procedure:

  1. Obtain a medium sized beaker
  2. Add 75-100 mL of water to beaker; set-up apparatus to heat your mixture over a Bunsen burner to begin heating.
  3. Measure out about 15 g of Copper(II) Sulfate Pentahydrate (CuSO4 . 5H2O) and record the mass in the data table. Then slowly add the crystals to the heating water.
  4. With a glass stirring-rod, stir the solution until the Copper(II) Sulfate Pentahydrate is dissolved.
  5. While the copper sulfate crystals are dissolving one member of the group can go and get the foil. Carefully weigh out a piece of aluminum foil that weighs between 0.7 and 1.0 grams. Record the mass exactly into the data table (hundredths place).
  6. Tear the foil into small pieces and carefully add it to the hot solution with continuous stirring until all the foil is placed into the beaker.
  7. St irring frequently, allow the reaction to occur until you can't see any more sliver foil pieces. This will take 15 to 20 minutes, so be patient. Once you can't see anymore foil pieces, no matter how small, heat an additional 3 to 4 minutes. Then remove from heat.
  8. Write your names around the outside edge of a filter paper (so you can claim it later), weigh and record the mass in the data table.
  9. Use the filter paper and your funnel to filter the residue in the beaker, catching the filtrate into the Erlenmeyer flask provided.
  10. Rinse out your beaker with a small (amount just covering the bottom of the beaker) of water to be sure you obtained all the product/residue
  11. Remove the filter paper from the funnel and spread it out on a paper towel to dry ove rnight.
  12. Clean and dry the glassware. Be sure the propane is turned off and Bunsen burner disconnected and put away. Straighten up your area.
  13. Upon returning the next day, weigh the filter paper and dry the residue and record the mass in the data table, Throw the paper and residue away.
  14. . Straining Process


Conclusion

When we finished our experiment, we weighed the amount of copper that we had, and it ended up weighing .41g. Here is a table showing masses of the stuff

Here is the Reaction that occurred again... just in case you are confuzzled and do not feel like scrolling back up to the reaction toward the top of the page

3CuSO4 + 2Al --> Al2(SO4)3 + 3Cu

Thursday, March 18, 2010

Lab: Types of Chemical Reactions


TYPES of CHEMICAL REACTIONS

In this lab we performed various chemical reactions in the lab. We recorded our observations and identified the type of reaction that took place, eventually writing a balanced chemical equation. The purpose of this lab was to become more familiar with the five types of chemical reactions: synthesis, decomposition, single-displacement, double-displacement, and combustion.


Introduction/Background:

Here are some descriptions of the different types of reactions:

Synthesis - when there is a combination of 2 or more substances and a compound results; A+B->AB.


Decomposition - opposite of synthesis. when a compound is broken down into simpler substances, usually through electrolysis; AB -> A + B


Single-Displacement - A metal replaces a metal, or a nonmetal replaces a nonmetal; A + BC -> AC + B

Double-Displacement - A metal replaces a metal, and a nonmetal replaces a nonmetal; AB + XY -> AY + XB
Combustion - when all substances in a compound are combined with oxygen which then produces carbon dioxide (CO2) and water (H2O).


Combustion is commonly called burning because it is an exothermic reaction (heat is produced); CxHy + O2 -> CO2 + H2O




MATERIALS:
  • Safety Gear (goggles and apron)
  • 3 test tubes
  • test tube rack
  • Bunsen burner
  • copper sulfate (CuSO4)
  • Zinc Metal (Zn)
  • Barium Nitrate (Ba(NO3)2)
  • Hydrochloric Acid (HCl)
  • Hydrogen Peroxide (H2O2)
  • Magnesium Oxide (MnO2)
  • Splints

PROCEDURE: Obtain 3 small test tubes after putting safety gear on.
  1. In the 1st test tube, place a piece of zinc and about 1/2 mL of CuSO4 solution. Record observations.
  2. In the 2nd test tube, add about 1/2 mL Ba(NO3)2 solution to about 1/2 mL of CuSO4 solution. Record observations.
  3. In the 3rd test tube, place a piece of magnesium ribbon. Add about 1/2 mL of HCl solution. Record observations.
  4. Light a bunsen burner (burning propane gas, C3H8). Record observations of the flame.
  5. Rinse out the first test tube. Add about 2 mL H2O2 solution. Lightly heat it. Record observations.
  6. Add a pinch of MnO2 (catalyst) to the H2O2 solution. Lightly heat it. Record observations.

DATA / ANALYSIS

In performing these chemical reactions, we have learned of the possible types and different products that can result from the many combinations of solutions. For instance, there are many different combinations that a solid(s), gas(g), or liquid(aq) can result in the other.


BALANCED EQUATIONS

1. Zn + CuSO4 --> ZnSO4 + Cu Single-Displacement Reaction

2. Ba(NO3)2 + CuSO4 --> BaSO4 + Cu(NO3)2 Double-Displacement Reaction

3. Mg + 2HCl --> MgCl2 + H2
Single-Displacement Reaction

4. C3H8 + 5O2 --> 3CO2 + 4H2O
Combustion Reaction

5. 2H2O2 --> 2H2O + O2
Decomposition Reaction





Observations/ Conclusions:

  • Some form of noticeable change occurred in each of the reactions (dur du dur)
  • In reactions releasing oxygen or hydrogen (bubbles) created a reaction from the lit splint (relighting of flame or spark/pop)
  • Zinc has a higher reactivity than copper
  • In the Barium Nitrate + Copper Sulfate Reaction, there was a distinct change in color and the powder that formed sunk to the bottom (picture to the right)

Friday, February 19, 2010

Lewis Structures and Molecular Shape

Shapes and Lewis Structures of Molecules

Background Information:

Everything is made out of different kinds of molecules. These molecules are made out of different combinations of atoms that are brought together by different kinds of bonds. We did this lab to better understand how these bonds are formed and what kind of molecules are made from these different bonds. These bonds occur when the electrons of an atom share themselves with those of another.

The best way to do this is to first make a lewis structure of the molecule you are inquiring. Lewis structures are diagrams that show the bonding between different atoms of a molecule, and the lone pairs of electrons that may exist in the molecule. It can be drawn for any covalently-bonded molecule. It was named after Gilbert N. Lewis, who introduced it in his 1916 article The Atom and the Molecule.

Reasoning For Experiment:

We did this experiment to better understand the way different molecules bond to one another and the shape they attain in the process. Analyzing the structure, you are able to obtain more information about its changes in properties and the polarity of the molecule.

Materials:

Here are is a picture of what we used to make our models for this lab



Procedure:

  1. Build a model for each of the molecules listed on the data table on the back of this page.(Remember that some atoms can form multiple bonds.)
  2. Draw the three-dimensional structure of each molecule in Table 1. (make a copy of Table 1 on your own paper) Use solid lines to represent bonds in the plane of the paper, and wedged lines for bonds that point of from the plane of the paper toward the viewer.
  3. Note that the shape of each molecule in the third column of Table 1, the bond angles in column 4, whether or not they will be polar in column 5, and whether or not they exhibit resonance structure in column 6.

Results:


Here is a data table of 6 different molecules we decided to post. Included is the name of the Molecule, the Lewis Structure of it, the ball stick model, the shape, and the polarity of each. For the N2 molecule, we put in an incorrect structure in as an example. It should have a triple bond instead of a single bond. The SO3-2 Molecule was the only resonance structure included in this experiment. This means that it can have multiple ways of bonding and still result in to the same molecule and shape.


Click on Table for better clarity



Analysis Questions:

Explain how water's shape causes it to be polar.

Water is polar due to the fact that the hydrogen atoms only have their proton on the outside, where the electrons are bonded to the oxygen and the extra negative atoms of the oxygen are on the other side, making the molecule polar


Describe how water's properties would be different if the molecules were linear instead of bent.

If water was linear, there is a chance that the water would become non-polar, changing the way it reacts with other atoms and molecules.

Thursday, February 4, 2010

Paper Chromatography Lab

Paper Chromatography Lab

Chromatography Lab


Before we start, let us tell you a little bit more about what chromatography actually is and why it is used.


About Chromatography:


Chromatography is a procedure that is used to separate mixtures. This involves passing a mixture through a stationary phase, also known as a "mobile phase". As the mixture goes through the mobile phase, subtle differences in concentrations of each part of the mixture. It was first used in the mid 19th century primarily to separate plant pigments, most likely chlorophyll. It is attributed to Russian botanist Mikhail Semynovich Tsvet who used columns of calcium carbonate for seperating plant pigments during the first decade of the 20th century during his research of chlorophyll.



Reasoning for Experiment:

This experiment is to help us learn more about the bonds of different mixtures and compounds


Problem Statement:

Compare different solvents' polarity and ability to separate a mixture into its pure components.

Hypothesis:

Due to its attractive force that would allow the solution to move up the paper, we believe water will extract the solvent, moving the ink up the chromatography paper.

Materials:

Solvents - H2O (water), CH3OH (methanol), C3H7OH (propanol), and C6H14 (hexane)

Mixtures - Water-soluble overhead pens (black, red, green, blue, and yellow)


24-well plate

Chromatography paper strips (1 cm x 8 cm)

Safety materials (apron and goggles)


Procedure:
PART 1

Before you start the lab, put on safety apron and goggles to prevent injury to hazardous material. Be careful, some of the mixtures are dangerous and should be used under a fume hood. First of all, cut chromatography paper into 1 cm x 8 cm strips. Fold the strip about 1.5 cm from one end. Put a pencil line near the crease and dot black marker across the pencil line. Be sure to allow the ink to dry. Label each strip on the opposite end with a pencil. Then, fill 4 separate wells on the 24-well plate approximately half full of the following solvents.

H2O, CH3OH, C3H7OH, and C6H14. (Beware, some of these fumes can be dangerous)

Next, place the chromatography paper strips into the solvent, not allowing the marker dots to be inserted into the solvent. Last of all, record your observations as you let the solvent to wick up the paper for 1/2 hour.

PART 2

Choose the solvent that best separated the ink's pigment from PART 1 and test its ability to separate different colors. Obtain 4-5 strips of chromatography paper, depending on how many colors you have, repeating the steps for labeling and adjusting the strips. Next, fill that many separate wells of the 24-well plate with a single solvent 1/2 full. Place the strips into the solvent, not allowing the marker spots to enter the liquid. Again, allow the solvent to wick up the paper for 1/2 hour. Record observations, sketching the results as shown for water.












Results:

As you can see in the photo above, red and green ink seem to have a variety of pigments compared to blue and yellow, which consist of only its own color.


Conclusion:

After experimenting with the solvents and inks, we conclude that our hypothesis is correct. Water transferred the ink up the chromatography paper the most effectively out of all the solvents.

Listed from best to worst solvents: H2O, CH3OH, C3H7OH, and C6H14

From doing this lab, we learned about chromatography paper and its ability to reveal information about certain solvents.

Anomalies

This Experiment could have been more interesting and a learning experiment if we had a wider range of colors and chemicals to work with.