2. Methods

Part A

Equipment list:
9V batteries x4
22-gauge electrical wire
Alligator clips x12
Wire cutters and strippers
Breadboard, about 3" x 2"
10K Ohm resistor
Voltmeter/Multimeter (must be able to read 10 millivolts)
Cola; any brand, such as Coke, Pepsi, or a generic brand, will work
Cup or jar that the nickel metal strips can completely fit inside (1); must be taller than 5 inches.
250 mL beaker
Small Styrofoam block
Nickel metal strips x2 ; strips should be approximately 5 inches tall and ¾ inch wide.
0.1 M phosphate buffer solution, pH 7.0 (500ml)
This buffer should contain 2.63 g monopotassium phosphate (KH₂PO₄) (FW 136.09 g/mol) and 4.35 g sodium phosphate (Na₂HPO₄) (FW 141.96 g/mol) (to lower the pH to 7.0) and brought to 500 mL using deionized (DI) water for a total phosphate concentration of 0.1 M.
Magnetic stir plate and stir bar x1
Pair of disposable gloves
Metal scoop for chemicals
Cobalt Nitrate (10 g)


• Procedures: Detail all procedures and experimental design to be used for data collection



Creating the Galvanostatic Electrochemical Cell

1.Build a circuit on the breadboard consisting of the batteries, resistor, and voltmeter/multimeter.


2a Connect the four 9V batteries in series using some wire and 6 alligator clips.Cut each piece of wire to the desired length with the wire cutters. When using wire to attach components in a circuit, the ends of each piece of wire need to be stripped, with the wire stripper, before creating the connection. Connect the batteries so that the negative end of one battery is connected to the positive end of the next battery in the series.
Chem_img126.jpg

Figure 1 : This diagram shows how two different type of breadboards can be wired into a circuit with the various electrical components and also shows the correct completed circuit.

 b Using a piece of wire, connect the positive end of the series of batteries to the breadboard power bus

 c Connect the 10K Ohm resistor

 d Connect the positive (red) lead from the voltmeter/multimeter to the breadboard

 e Connect the negative (black) lead from the voltmeter/multimeter to the breadboard

 f Using a piece of wire, attach the negative (-) end of the series of batteries to the ground bus (far right column) of the breadboard



3.Using the voltmeter/multimeter, make sure the circuit reads >30V

4.Use the nickel metal strips as electrodes. The nickel electrodes will serve as the scaffold for formation or electroplating of the cobalt catalyst.

a To clean the electrodes (nickel metal strips), pour some cola into a cup or jar. Put both electrodes in the cola. Make sure the nickel is entirely immersed. Cola contains phosphoric acid. This acid will do a great job of cleaning the surface of the electrodes. After a few minutes, remove the nickel electrodes, wash them off with plain water, and dry them.
If the jar is too small to immerse the electrodes, do the procedure once then flip the electrodes over (putting the end that was not previously immersed in the Cola) and repeat.

 b Construct a method to secure electrodes within a small beaker or jar that leaves the top of the electrodes readily available to make an electrical connection to the rest of the circuit you started preparing above. It is important to ensure that the separation between the electrodes remains the same throughout the experiment. When securing the electrodes make sure to:
Position the electrodes 1-2 centimeters (cm) apart.
Make sure the electrodes are securely in place and not dangling freely or touching the sides of the beaker.
Position the electrodes so that they will, later, once the buffer has been added to the beaker, only be immersed half way in the buffer. Note: It is critical that the top of the electrodes do not touch the buffer.
Chem_img091.jpg
Figure 2: This is an example of how the nickel electrodes can be suspended in the beaker to make an electrochemical cell


5. Add 0.1 M phosphate buffer solution, pH 7.0, to the beaker with electrodes so that the nickel electrodes are submerged half way in the buffer solution.

6. Place the stir bar in the bottom of the jar.
Make sure that the electrodes are not so low that they will be bumped by the stir bar. If they are, raise them up until they are not.

7. Connect the nickel electrodes to the rest of the circuit using copper wire and alligator clips
For both types of breadboards shown, one wire is connected to a position in the same row as the voltmeter/multimeter's positive lead, and the other wire is connected to a position in the same row as the voltmeter/multimeter's negative lead (on the other half of the breadboard).
Figure 3 : The pictures on the right shows the final circuit after connecting the electrodes. The top picture is a close up picture of how the circuit should be connected in real life and the bottom is the schematics of the circuit.

Adding the Cobalt Catalyst and Measuring Its Effects
1. With the electrodes securely in place inside the small beaker, place the beaker on the magnetic stir plate. Turn on the stir plate and get the stir bar moving at a constant rate.
Make sure that the stir bar does not bump the electrodes. Adjust the electrodes if needed, but then keep them in the same position throughout the rest of the experiment.

2. Monitor the voltage readout on the voltmeter/multimeter. It should range between 1.9-2.4v and will take at least five minutes to stabilize. After the voltage reading has stabilized, record this voltage in your lab notebook. Repeat step 1 and 2 three times then take the average voltage of the three. This is the baseline average voltage value for the electrochemical cell.

3. Put on a pair of disposable gloves and, using the metal scoop, add a pinch of the cobalt nitrate to the jar with the phosphate buffer.  With the cobalt source and the energy provided by the batteries, the catalyst will start to form.
Adding small amounts of cobalt nitrate each time is critical. The cobalt nitrate concentration must remain very low so the solution does not become cloudy
Figure 4 : This shows that only a small amount of cobalt nitrate should be added to the buffer each time

4. The cobalt-based catalyst will begin to electroplate onto the anodic (connected to + side of the battery) nickel electrode. As the catalyst film grows, you will see a brown film growing on the anode, and the voltage readout on the voltmeter/multimeter will slowly drop. Eventually, after several minutes, the voltage will settle to a stable reading.
As the reaction takes place, you will see tiny bubbles forming on the nickel electrodes
Chem_img097.jpg
Figure 5 : The picture on the right shows no bubbles emerging from the cobalt nitrate and the picture on the left shows the progressing reaction of the gases formed, creating tiny bubbles that are covering the nitrate.

5. Once the voltage readout stabilizes, you can add more cobalt nitrate to the solution to initiate formation of more cobalt-based catalyst. Again, add only a small amount of cobalt nitrate at a time.

6. Repeat step 5 until the voltage does not appear to change with the addition of more cobalt nitrate. In this instance, the cobalt-based catalyst will continue to work, but no additional catalyst material will form.

7. Repeat steps 3-6 three times to get an average measured voltage.

8. Compare the average baseline voltage recorded earlier and the average measured voltage in a table.

• Risk and Safety: Identify any potential risks  and safety precautions to be taken.

1. Connecting the 9V batteries
- Can cause burns or electric sparks when handled inappropriately
- Can ignite fires therefore, is level 2/4  of posing threats.
- Vulnerability : People might get burnt and if is nearby a flammable object, the room may catch fire, causing casualties, property damage, environmental contamination.
Precautions: - Do not expose to fire
- Read and follow precautionaries on battery
- Do not attempt to open battery
- If leaking or damaged, immediately dispose it correctly
- Make sure area is well ventilated
- Never lean over battery when testing or charging or experimenting
- Ensure components and wiring do not come into contact with each other to cause a short circuit.



2. Cobalt Nitrate
- They can cause skin and eye irritation/ To those who have sensitive skin, it will cause rash.
- Is not deadly, however for those who have allergies , they might be hospitalized. Also, if it comes into contact with the eye, it may cause blindness or decrease vision abilities.
- Only affects people. Does not do damage to inanimate objects  Might cause environmental contamination if not disposed correctly
- Do not eat.
Precautions:    - Wear Lab Goggles
               - Wear disposable gloves
- Handle with care
- Keep the lid sealed after use
- Place it at a safe corner

• Data Analysis: Describe the procedures you will use to analyze the data/results that answer research questions or hypotheses

1. To measure the efficiency of the phosphate buffer without cobalt , we use a equation:
Figure 6: The formula for calculating efficiency of the cobalt

1.23V is the necessary voltage needed to maintain 3mA current when there is no resistive loss and if the water splitting reaction was completely efficient. (We calculated current by I=V/R.

2. To measure the efficiency of the phosphate buffer with cobalt, we also use the same equation however we change the ideal voltage and there is same current.

3. We then compare them from there with a table.


Part B

Equipment list:
- Model cars x2
- Styrofoam cutter/ hacksaw
- Ruler
- Styrofoam boxes x3
- Track
- Pen
- Photogates x2
- Data Logger

• Procedures: Detail all procedures and experimental design to be used for data collection
Building cars and shapes
1. Build the model car, following the instructions given in the box provided. Then, record the rough measurements by a ruler.
2. Pen and draw the shapes you want to make (at least 4), noting the exact measurements of the width of the car, height and length. Label the measurements onto the final draft.
3. Following the draft, take a styrofoam box and begin using a hacksaw to form out the shape. Place a dustbin below to collect the debris. Start hacking until you form out the rough shape and polish it with sandpaper on a wooden block to smoothen the edges and the surface.
Figure 1: A styrofoam block and a hacksaw example and a picture of what we can do with a hacksaw on a styrofoam block.

4. Follow step 3 with the remaining desired shapes.
5. Remove the original cover of the car that is provided in the box since we will only need the body of the car.
6. Use black insulating tape to attach the shapes that we want to the car as other stronger tapes will only damage the shape of the styrofoams or the car itself.

Record the speed
1. Build the track and lay it out on a secluded area without weather change that will affect the track itself
2. Record the speed of the car without any change to the shape of the car (Styrofoam). This will be our control setup.
3.Record the speed of the car when it is equipped with the different styrofoams and record it down in a graph, this will help us see which shape of the car is the fastest/slowest.
4.There will be photogates set up at various areas that will allow us to record the speed with the most amount of accuracy.
Figure 2: An example of photogates set up on a track

4. The photogate will be connected to the data logger which will be connected to the track, retrieving the most accurate data.

5. The results will be collated at the data logger which we will take from and tabulate the data into our logbook.


• Risk and Safety: Identify any potential risks and safety precautions to be taken.

1. Hacksaw
Hacksaw is used for cutting materials such as wood, styrofoam etc. It resembles a saw therefore there are sharp edges. Vulnerability is Level 3 as it can contaminate your skin if cut
Precautions:   -Don't leave it lying around
-Make sure you hold it by the handle

2. Styrofoam
Styrofoam is an everyday product however it contains a harmful ingredient called Polypropylene that can cause irritation of eyes and skin and effects on the nervous system. The vulnerability level is Level 4.
Precautions:   - Recommended to use styrofoam cutter
- Do not get too close to the styrofoam; do not sniff.
- Cut the block of styrofoam beside a bin such that the shavings fall into the bin instead of the ground and table

• Data Analysis: Describe the procedures you will use to analyze the data/results that answer research questions or hypotheses
1. Tabulate the data collected from the light sensor and photogates after each trial.
2. Calculate the average timing for each shapes.
3. Using distance= speed X time formula, calculate the speed of the cars from the timing recorded.
4..Put the data into a bar graph and conclude the findings.

No comments:

Post a Comment