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Tuesday, May 29

  1. file Recording.wav uploaded
    6:48 am
  2. page Ant Trail Pheremone edited ... Lab Revisited: We revisited the electroplating portion of the lab and conducted 5 additional …
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    Lab Revisited:
    We revisited the electroplating portion of the lab and conducted 5 additional trials using various voltages. Our additional trials supported the conclusion that copper was successfully plated out of solution. The 5 additional trials also refined our methodology for doing so.
    //TODO MethodologyProject Topic:
    Refining of Ores by Electrowinning (Reduction of Oxides)
    Chemistry Concept:
    Most ores are either oxides or sulfides. Sulfides can be easily converted into oxides by heating in the presence of oxygen, so our lab will focus on the oxides. To recover the pure metal, the compound has to transfer its oxygen to another atom or atoms. There are three main methods of doing so: pyrometallurgy, which uses heat to break the metal-oxygen bond, electrometallurgy, which uses electric current to electroplate a pure metal cathode, and hydrometallurgy, which uses aqueous chemistry to reduce the metal. The metal used will be copper. We will use pyrometallurgy to create a solid, somewhat pure sample, which will be further refined with electrometallurgy. We will investigate the relationship between current and rate of plating.
    Hypothesis:
    A high current will be directly proportional to rapid plating. Pyrometallurgic methods of purification will result in less pure copper than electrometallurgy.
    .
    Journal Articles:
    Pyrometallurgy: http://tinyurl.com/7jdu7xo
    Electrometallurgy: http://tinyurl.com/893nfph
    Lab Procedure:
    Pyro:
    Mass out ~10 g of copper oxide, record
    Acquire two sections of glass tubing each about ~9-10 inches in length. Using a bunsen burner bend one into a L shape and one into a Z shape.
    Attach both sections of tubing to a double holed stopper. The Z shaped tube will be a gas flare; make sure it is as far away as possible from the L shaped gas input.
    Place copper oxide powder in test tube (mass test tube) and and secure tube to ring stand horizontally. Place stopper with tubing into test tube and attach L shaped glass tube to methane input (using length or rubber tubing.) Before moving to step 4, make sure copper oxide is spread along the wall of the test tube not clumped in the end.
    Open the valve to allow methane to flow into the test tube and light gas flare at end of Z shaped tube.
    Use a Bunsen burner to heat copper oxide until it changes color (from black to light pink.)
    Once all the copper oxide has visibly reacted, turn off the Bunsen burner. DO NOT TURN OFF THE GAS FLOWING THROUGH THE TEST TUBE! THIS WILL CAUSE THE COPPER TO OXIDIZE.
    Wait until the test tube and its contents have cooled to room temperature, then stop the flow of gas through the test tube and remove stopper. DO NOT OPEN THE TEST TUBE NEAR AN OPEN FLAME, ALLOW EXCESS METHANE TO DISPERSE SAFELY.
    Re mass the test tube and record the new mass. Calculate percent yield.
    Electro:
    Fill a 500mL flask with 100 mL 1.0 M sulfuric acid
    Mass out 4.0 g of copper sulfate, and add to the beaker
    Acquire a section of copper wire, (twist into a spiral pattern to maximize surface area in sulfuric acid solution.) Mass and record
    Create anode
    For graphite, bind together 10 sticks of pencil lead with a copper wire. Mass and record.
    For direct contact, clamp a nickel coin in a pair of tweezers, and wrap wire around the middle to keep the tweezers closed.
    If using a graphite anode, mass the nickel.
    Attach the copper wire to the black wire (negative), and the anode to the red (positive) terminal of the current source, and place stopper in beaker. MAKE SURE ANODE AND CATHODE ARE NOT TOUCHING. For a graphite anode, place the nickel underneath the anode.
    Set the current source to a predetermined voltage. In both cases allow the solution to sit, with current on,
    for electroplating45 minutes.
    Every 5 minutes, and at
    the second time.start of the experiment, record both voltage and current from the power source.
    After 45 minutes, remove electrodes, and mass anode, cathode, and nickel.
    Apparatus and Chemicals Needed:
    Substrates:
    Copper(II) oxide
    Pyro:
    Bunsen Burner
    Ring Stand
    Clamp
    Test tube
    Glass tubing
    Rubber tubing
    2xMethane sources
    Double Hole Stopper
    Electro:
    Copper sulfate
    Copper wire
    Tweezers
    1.0 M Sulfuric acid
    Current source
    U.S. nickel (pre-1945)
    Other:
    Digital scale, plexiglass shield
    Safety Information:
    Do not inhale, ingest or touch the copper (II) oxide or copper sulfate.
    Be wary of hot glassware and fire hazard when using methane to reduce copper (II) oxide. Place plexiglass shield between observer and apparatus.
    Do not inhale, ingest or touch sulfuric acid. Handle with care and dispose of properly.
    Use fume hood for electrolysis.
    Do not touch electric leads during electrolysis.
    Material Safety Data Sheets:
    Copper(II) oxide
    Copper(II) sulfate
    Methane

    Data Collected:
    Initial Conditions TableTable 1: Masses of Compounds During Smelting
    Mass
    Empty test tube
    18.42 g
    Copper oxide
    2.5 g
    Test Tube and copper
    20.57 g
    Table 2: Initial conditions for Electroplating

    Trial 1
    Trial 2
    ...
    96.0 mL
    100.0 mL
    Current andTable 3: Voltage Tableand Current Measurements for Electroplating
    Trial 1
    Trial 2
    ...
    4.4 V
    3.04 A
    Final Conditions TableTable 4: Final conditions for Electroplating
    Trial 1
    Trial 2
    ...
    N / A
    N / A
    Table 5: Mass Changes in Components
    Trial 1
    Trial 2
    Trial 3
    Control 1
    Control 2
    Change in Cathode
    0.99 g
    0.127 g
    1.414 g
    6.413 g
    4.176 g
    Change in Anode
    0.047 g
    4.458 g
    4.05 g
    N / A
    N / A
    Change in Nickel
    0.049 g
    4.629 g
    4.385 g
    N / A
    N / A
    Change in Anode + Nickel
    0.096 g
    9.087 g
    8.435 g
    2.72 g
    2.275 g
    Table 6: Total Charge Transferred

    Current to Charge Table
    Trial 1
    (view changes)
    6:37 am

Saturday, May 26

  1. page Mpemba Effect edited ... MPEMBA EFFECT. Maddeline Graham and Laura Dahl. The purpose of this lab was to attempt to recr…
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    MPEMBA EFFECT. Maddeline Graham and Laura Dahl. The purpose of this lab was to attempt to recreate the Mpemba effect and isolate some of the factors involved. The Mpemba effect occurs when two equal volumes of water, one hotter than the other, are placed in a subzero environment and the relatively hotter quantity freezes first. The variables tested were container material (conductive metal v. insulating plastic), open versus closed system and, in a separate part of the experiment, volume. It was concluded that the Mpemba effect was not achieved in any of the trials, that container material did not significantly affect the freezing rate of the water, and that whether the system was open or closed had a negligible effect of the freezing rate. The variables were chosen based on the principles surrounding the Mpemba effect including thermodynamics, thermochemistry, and properties of freezing water such as supercooling and the difference between reaching the freezing temperature and actually freezing the water completely. In addition, the open versus closed trials of the experiment was designed to isolate the effect of evaporative cooling, cooling in which relatively fast-moving, hot water molecules on the surface leave, removing heat energy from the body of water. This experiment examined the rates of cooling to 0°C of the various volumes of water with one of two initial temperatures, 21°C or 100°C. Despite the predicted outcome, a successful reproduction of the Mpemba Effect, the initially 21°C water consistently reached 0°C before the initially 100°C water. The Mpemba effect could be effectively applied to any operation which requires the rapid freezing of water or in planning the infrastructure of buildings so as to prevent pipes from bursting in cold weather.Keywords: supercooling, Mpemba effect, thermodynamics, evaporative cooling, thermochemistry, freezing point
    {figure_of_apparatus.jpg} Figure 1: Freezer, LoggerPro, laptop, open plastic and metal containers, temperature probe setup
    {freezer2.JPG}
    Figure
    Figure 2: Phase Two Walk-In Freezer Set Up
    Figure 3:
    Summary Graph
    {Graph1.JPG}
    Figure 3:4: Summary Figure
    {graph2.JPG}
    Mpemba Recording:
    Mpemba Effect.wav
    Works Cited
    Brownridge, J. D.(2011). When does hot water freeze faster then cold water? A search for the Mpemba effect. American Journal Of Physics, 79(1), 78-84. doi:10.1119/1.3490015
    Monwhea, J. (2006). The Mpemba effect: When can hot water freeze faster than cold?. American Journal Of Physics, 74(6), 514-522. doi:10.1119/1.2186331
    (view changes)
    5:55 am
  2. page Mpemba Effect edited ... MPEMBA EFFECT. Maddeline Graham and Laura Dahl. The purpose of this lab was to attempt to recr…
    ...
    MPEMBA EFFECT. Maddeline Graham and Laura Dahl. The purpose of this lab was to attempt to recreate the Mpemba effect and isolate some of the factors involved. The Mpemba effect occurs when two equal volumes of water, one hotter than the other, are placed in a subzero environment and the relatively hotter quantity freezes first. The variables tested were container material (conductive metal v. insulating plastic), open versus closed system and, in a separate part of the experiment, volume. It was concluded that the Mpemba effect was not achieved in any of the trials, that container material did not significantly affect the freezing rate of the water, and that whether the system was open or closed had a negligible effect of the freezing rate. The variables were chosen based on the principles surrounding the Mpemba effect including thermodynamics, thermochemistry, and properties of freezing water such as supercooling and the difference between reaching the freezing temperature and actually freezing the water completely. In addition, the open versus closed trials of the experiment was designed to isolate the effect of evaporative cooling, cooling in which relatively fast-moving, hot water molecules on the surface leave, removing heat energy from the body of water. This experiment examined the rates of cooling to 0°C of the various volumes of water with one of two initial temperatures, 21°C or 100°C. Despite the predicted outcome, a successful reproduction of the Mpemba Effect, the initially 21°C water consistently reached 0°C before the initially 100°C water. The Mpemba effect could be effectively applied to any operation which requires the rapid freezing of water or in planning the infrastructure of buildings so as to prevent pipes from bursting in cold weather.Keywords: supercooling, Mpemba effect, thermodynamics, evaporative cooling, thermochemistry, freezing point
    {figure_of_apparatus.jpg} Figure 1: Freezer, LoggerPro, laptop, open plastic and metal containers, temperature probe setup
    {freezer2.JPG}
    Figure 2: Summary Graph of Freezing Times: by Container Type
    {Graph1.JPG}
    (view changes)
    5:53 am
  3. file freezer2.JPG uploaded
    5:52 am
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    5:51 am
  5. file Graph1.JPG uploaded
    5:50 am

Friday, May 25

  1. page Dilatant Solutions edited Abstract: IMPACT IMPACTS OF VOLUME ... FOR DILATANT COLLOIDS. COLLOIDS AND OF SOLVENT POLARI…
    Abstract:
    IMPACTIMPACTS OF VOLUME
    ...
    FOR DILATANT COLLOIDS.COLLOIDS AND OF SOLVENT POLARITY ON DILATANCY. Sam Wood
    ...
    cornstarch and water.water and to determine the influence of the polarity of the solvent on the dilatancy of cornstarch-based mixtures. In the
    ...
    cornstarch and water were prepared,water, with volume
    ...
    2:1, and 11:5.11:5, and three mixtures of cornstarch and heptane (C7H16), with volume fractions 1:1, 2:1, and 3:1, were prepared. The force
    ...
    cause the cornstarch and water mixtures to
    ...
    varying mass. Force data were also collected for solid ice, liquid water, and a gel-like mixture of water and gelatin to establish a point of reference for the behavior exhibited by the cornstarch and water colloids. The data collected for the cornstarch and water colloids support the
    ...
    force decreases. TheAs expected, the critical shear
    ...
    dilatant materials. However, they doObservations of the cornstarch and heptane mixtures, which did not distinguish betweendemonstrate dilatant behavior, suggest that the electrostatic-attraction andmodel may be more viable than the polymer-tangling modelsmodel for jamming within colloids of cornstarchcornstarch-based colloids. However, due to the large size differences between water and water.heptane, the results do not necessarily distinguish between the two models. Unexpectedly, theythe results of the experiment suggest that
    ...
    distinguish between these twothe electrostatic-attraction and the polymer-tangling models and
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    is a gradual range rather
    ...
    exact value.
    Keywords:
    Keywords: dilatancy, colloid,
    ...
    hydrocluster, volume fraction.fraction, heptane.
    Lab Apparatus:
    {lab_apparatus.jpg}{lab_apparatus.png}
    Summary Graphic:
    3:2 Volume Fraction
    100 g Weight
    200 g Weight
    Average Force Exerted
    Without Colloid:
    With Colloid:
    Without Colloid:
    With Colloid:
    19.0 N
    9.0 N
    44.0 N
    35.0 N
    2:1 Volume Fraction
    50 g Weight
    100 g Weight
    Average Force Exerted
    Without Colloid:
    With Colloid:
    Without Colloid:
    With Colloid:
    15.0 N
    7.5 N
    16.5 N
    16.0 N
    11:5 Volume Fraction
    5 g Weight
    Average Force Exerted
    Without Colloid:
    With Colloid:
    1.6 N
    1.6 N
    {finished_thingy.jpg}
    The numbers on the bars denote the force exerted on the substance during the trial.
    Recording:

    References:
    Efremov, I. F. (1982). The dilatancy of colloidal structures and polymer solutions. Retrieved from http://iopscience.iop.org/0036-021X/51/2/R05
    ...
    Smith, M. I., Besseling, R., Cates, M. E., & Bertola, V. (2010). Dilatancy in the flow and fracture of stretched colloidal suspensions. Nature Communications, 1(114), 1-5. doi:10.1038/ncomms1119
    Wagner, N. J., & Brady, J. F. (2009). Shear thickening in colloidal dispersions. Physics Today, 62(10), 27-32.
    3:2 Volume Fraction
    100 g Weight
    200 g Weight
    Average Force Exerted
    Without Colloid:
    With Colloid:
    Without Colloid:
    With Colloid:
    19.0 N
    9.0 N
    44.0 N
    35.0 N
    2:1 Volume Fraction
    50 g Weight
    100 g Weight
    Average Force Exerted
    Without Colloid:
    With Colloid:
    Without Colloid:
    With Colloid:
    15.0 N
    7.5 N
    16.5 N
    16.0 N
    11:5 Volume Fraction
    5 g Weight
    Average Force Exerted
    Without Colloid:
    With Colloid:
    1.6 N
    1.6 N

    (view changes)
    12:28 pm
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