Tuesday, November 30, 2010

Pennies, Pennies, PENNIES!

INTRODUCTION
The Pennium Lab will investigate the concept of atomic mass and how it was derived. You will be given a bag of pennies, you will discover how many different pennuim isotopes are in the bag. You will then determine the average atomic mass of pennium using the following equation: (average mass of isotope 1)(percent abundance of isotope1) + (average mass of Isotopes 2)(percent abundance of isotope 2)

 MATERIALS
-Pennies!
-Dimes!
-Nickels!
-and Quarters!
-Triple Beam Balance scale!


PROCEDURE PART 1
Step 1: Obtain a packet of pennies.
Step 2: Sort the pennies into two groups: pre 1982 and 1982 and newer.
Step 3: Measure the mass (in grams) of each stack of pennies. Record the mass (in grams) of each penny stack in a data table. Count the number of pennies in each stack.
Step 4: Measure the mass in grams of a half dollar, quarter, nickel, and dime. Record these values in a data table.
Step 5: Answer the questions below and then continue with Part 2


RESULTS OF PROCEDURE 1

 

Pre
Posts
Nickels
Dimes
Quarters

Mass
2.5
3.04
5
2.3
5.7
#
11
14
1
1
1
Average Mass
.5g
.61g
1g
.46g
1.14g








Questions:
1. Does each penny have the same mass? No
2. Can you identify two "penny isotopes" bases on masses of the pennies? Pre penny Isotopes and Post penny Isotopes.
3. What does you data tell you about the relationship between mass of a penny and date of a penny. Make a generalization.  Pre 1982 weighs more than Post 1982 pennies.

PROCEDURE PART 2
1. Determine the average mass of Pre-1982 pennies. (Record Average) 3.03g
2. Determine the average mass of post- 1982 pennies. (Record average) 2.59g
3. Determine the percentage of your pennies that is pre-1982 and the percentage that is post- 1982. These percents should add up to 100%. What you have calculated is the percent abundance of each group of pennies(penny isotopes). Post is 44% and Pre is 56%
4. Lets say that the mass of a nickel is one CMU (coin mass unit). Use the mass of a nickel to calculate the mass of a half dollar, quarter, dime, pre-82 pennies, post 82 pennies. Again, Show all calculations, and record all data in a data table like shown.
5. Determine the average mass of Pennium in CMU's using the percent abundance of each pennium isotope (pre- 82 and post- 82) and the mass of each pennium isotope in CMU's.
(3.03 times .56) + (2.5 times .44) = 2.8 CMU

CONCLUSION
The post pennies have a bigger mass than the pre pennies. We derived the unit CMU by finding the mass of the nickel and used the Formula. The we used the Atomic mass average based to help find all of the elements in Atomic Mass.  So our conclusion is that the post pennies do have a bigger mass than the pre pennies. 







Monday, November 29, 2010

CANDY CANDY CANDY!

PURPOSE/ INTRODUCTION: 
      Use a "Candium" model to explain the concept of atomic mass also, analyze the isotopes of Candium and calculate its atomic mass. Atomic Mass is the average mass of atoms of an element, calculated using the relative abundance of isotopes in a naturally-occuring element. This lab should give us a relative idea of what atomic mass (atomic weight) is and how to find it. 
                                                      

MATERIALS:
  • Sample of candy (You could use sixlets, reese's candy, and skittles) 
  • Balance
  • A Smile!


PROCEDURE: 
  1. Obtain sample of Candium
  2. Separate it into its 3 isotopes. (Definition under the discussion/conclusion) 
  3. Determine the total mass of each isotope. 
  4. Count the numbers of each isotope. 
  5. Record the data and calculations in a data table.
  6. Create a data table that has each of the following:
      • Average mass of each isotope.
      • Percent abundance of each isotope. 
      • Relative abundance of each isotope. 
      • Relative mass of each isotope. 
      • Average mass of each isotope. 


OUR DATA TABLE:


                                         Gobstopper       Sixlets       M&M's       Skittles
Average Mass:                           1.815 g          .888g        .936g       1.01g
% Abundance:                        11.1%           27.7%       24.1%       37.1%
Relative Abundance:                 6                 15            13             20
Relative Mass:                      2.044g            1g           1.05g       1.14g
Average Mass of all:               .567g            .567g       .567g        .567g


DISCUSSION/CONCLUSION: 
During this lab, we calculated the atomic mass of each candy and used the triple-beam-balance to do so. 


Isotope: any of two or more species of atoms of a chemical element with the same atomic number and nearly identical chemical behavior but with differing atomic mass or mass number and different physical properties


Now, to explain the difference between percent abundance and relative abundance:
Percent Abundancethe percentage of each type of isotope that exists in a given sample of an element. 
Relative Abundance: the number of candy in each isotope. 


Comparing the total values of average mass between relative mass:
Average Mass: the weight of each individual piece of candy. (Weigh all of them and divide by how many there are) 
Relative Mass: the comparison to the smallest mass there is, for example, divide the average mass of the  Gobstopper by the average mass of the Sixlets because they have the smallest mass. 
So, the relative mass of each candy is different because it compares each candy to a Sixlet. And each group will have different relative masses because they have different variables: the type of candy, the number of candy in each group, and even how they read the scale. 


In order to get exact results on this activity, be sure to round correctly and read your scale right. Also, if you measure your candy in a cup or a bag be sure to subtract the weight of the container from what the triple-beam-balance says, or else all your calculations will be off from the beginning. This activity is a model for calculating atomic masses of real elements because it gives everyone the opportunity to practice and calculate data. Each real element has its own identity and using certain information, a person can calculate the atomic mass. 

Monday, November 8, 2010

Aluminum ions, Copper metal, Hydrogen gas... OH MY!

INTRODUCTION
The purpose of this Chemical Lab is to become familiar with the terms: qualitative, quantitative and make observations about chemical and physical changes. This lab gives us an introduction to the laboratory and makes us follow directions and respond to questions as we go along.


HYPOTHESIS:
Predicted that the aluminum foil would change color or completely disintegrate in the mixture.

MATERIALS NEEDED:
  • Beaker (150 or 250 mL)
  • Copper(II) Sulfate Pentahydrate - CAUTION: Toxic Substance
  • Sodium Chloride
  • Scoopula
  • 100 mL graduated cylinder
  • Stirring Rod
  • Thermometer
  • Small square of aluminum foil
  • Apron
  • Goggles


PROCEDURE:
First, make sure your not alone and form a group of two or more. Take all appropriate safety precautions, where appropriate clothing and safety goggles and safety apron. 
Get a beaker(150 or 250 ml), a 100 ml graduated cylinder, a scoopula, a thermometer, some aluminum foil, and a container holding some cupric sulfate pentahydrate. Go to the appropriate source and add some water in your beaker. The exact amount is not important, although it should be between 75 and 100 ml.
Now using your scoopula, obtain some of the copper (II) sulfate pentahydrate. Again the exact amount is unimportant, but your scoopula should be about one quarter filled with the solid. Place the CuSO4 5H2O in the beaker, and stir with the stirring rod until all the solid has dissolved.
Obtain the aluminum foil sample in front of you and crumple it into a loose ball. Place the aluminum ball into the copper (II) sulfate solution, and stir gently for about 15 sec. Write down detailed observation. 
Make sure your scoopula is clean (rinse with tap water and dry with a paper towel) and obtain a large scoop of sodium chloride from the labeled container. Add the NaCl to the beaker containing the copper(H) sulfate- aluminum mixture. Stir until all of the sodium chloride is dissolved and make detailed observations. 
After approximately 10 minutes, take your beaker over to the large funnel and beaker and slowly decant (pour) your mixture into the beaker. Then clean your beaker thoroughly with soap and tap water, and then a final rinse with distilled water. Make sure your lab station is clean, return everything to the proper place.

QUESTIONS TO ASK YOURSELF WHILE YOU PERFORM THIS EXPERIMENT:
After step 1: Make a qualitive and quantative observation of a physical property of the water. 
After step 2: The mixture you just made was CUSO4 in water. Is this mixture heterogenous or  
                      homogenous? Explain. 
After step 3: Once you added the aluminum foil, what observations can you make? What happened to 
                      the foil?
After step 4: Once you added the sodium chloride to the mixture, what happened to the foil? 

  • Did you see a physical or chemical change? 
  • How many states of matter do you observe? Describe, from all your observations, what they are. Which do you see in your beaker now?
  • Any idea what the red solid is that has dropped to the bottom of your beaker?          
DISCUSSION/CONCLUSION: 
We just observed a chemical reaction between copper ion and aluminum, which produced copper metal, hydrogen gas, and aluminum ions. During the course of the reaction we made several different observations that were all indicators of a chemical change. Some indicators of chemical change would be: Production of bubbles with no added heat, an increase in temperature, a change in color, and a percipitate-which in this case, was copper. 

After we begun our experiment, we made a qualitative and two quantitative observations of the physical property of the water in our beaker. Qualitative: It was clear, pure water. Quantitative: There was 90 mL of water in the beaker and it had a temperature of 20.8 Degrees Celsius. 

After we added the copper(II) sulfate, we noticed we had a homogenous mixture of clear, blue, liquid. HINT: If you want the copper(II) sulfate to dissolve quicker, use hot water. 

Once we added the aluminum foil ball to the copper(II) sulfate/water mixture... absolutely nothing happened. But the temperature had gone up by about 2 Degrees Celsius. 

However; after the addition of sodium chloride, the aluminum foil changed color from silver to a reddish-black color. It also developed bubbles on the outer surface even when no heat had been added. We also saw both a physical and chemical change; Physical: The color changed. Chemical: An element had formed on the outside and had fallen to the bottom of the beaker. We also noticed all states of matter, a solid (the foil), a liquid (the blue water mixture), and gas (bubbles), and we concluded that copper was the red solid that had formed and fallen in the beaker.

INDICATORS OF A CHEMICAL CHANGE:
  1. Formation of a Percipitate 
  2. Color Change
  3. Bubbles (without added heat)
  4. Increase in Temperature
CLEAN-UP:
  1. Clean your beaker well with soap and water, rinsing it last with distilled water. 
  2. Make sure your lab station is clean. 
  3. Return all safety equipment to its proper location.