The paper clip - Sample Essay
To investigate how the voltage of the electric current would affect the rate at which a metal is electroplated. Hypothesis If the voltage of the current supplied for electroplating is increased, then the mass of the copper metal deposited on the paper clip would also increase. In electroplating, the anode is the copper metal piece and the cathode is the paper clip. The electrons travel from the negative terminal to the positive terminal, hence allowing the paper clip in the negative terminal to be electroplated.
When plating the paper clip with copper, the copper metal piece undergoes oxidation while the cathode undergoes reduction, where: Anode (Copper Metal Piece): Cu(s) –> Cu2+(aq) + 2e- Cathode (Paper Clip): Cu2+(aq) + 2e- –>Cu(s) This happens through the flow of electrons in the circuit. When time taken for electroplating to occur is kept constant, the rate of electroplating would depend on the voltage of the electric current. From this formula: Q = It (Charge = Current x Time) If the time remains constant, only the current would affect the charge of the electricity flowing through the circuit.
This then leads to another formula: V = IR (Voltage = Current x Resistance) One can deduce that if the resistance of the circuit stays the same, the voltage of the electric current would be the only factor affecting the current. This would mean that when the voltage of the electric power supply increases, the electric current would also increase proportionately. As the current increases, the charge of the electricity would also increase, causing meaning that the flow of electrons in the circuit would also be faster.
If the flow of the electrons is faster, it would mean that the rate of electroplating would also increase within a fixed amount of time. Therefore, as the voltage from the power supply increases, the mass of the copper deposited on the paper clip would also increase. Variables Independent Variable: –> Voltage of the electric current – The voltage of the electric current will be altered through the 30V power supply. For each set of data, the voltage will increase by 2V each time. As the voltage of the electric current increase, the mass of the copper deposited on the paper clip will also increase.
Dependent Variable: –> Mass of the copper deposited on the paper clip – The mass of the copper deposited on the paper clip will depend on what the voltage of the electric current will be. As the voltage of the electric current increases, the mass of the copper deposited will increase, decrease or stay the same. This is measured through subtracting the final mass of the electroplated paper clip from the initial mass of the paper clip before electroplating, with units in g. Controlled Variables:
Time taken for electroplating – The time taken for the paper clip to be electroplated should remain the same, as if the time changes, the charge of the electric current would be affected, causing the results to be invalid as only the current is supposed to be the only factor affecting the charge of the electric current. If the charge of the electric current is affected, the mass of copper deposited on the paper clip will also be affected; therefore it must remain the same throughout the experiment. The time will be measured using a stopwatch, and be maintained at 30 seconds with units in s.
Concentration of the copper sulphate solution – The concentration of the CuSO4 solution should remain the same, as if the concentration of the electrolyte changes, the products formed at the anode and cathode would differ in volume, hence affecting the mass of the copper deposited on the paper clip. It will be maintained at 0. 1mol. –> Volume of the copper sulphate solution – The volume of the CuSO4 solution should remain the same, or else the amount of copper ions in the solution would be different, which would in turn affect the rate of electroplating of the copper metal on the paper clip.
It will be measured using a 25cm3 measuring cylinder and be maintained at 100cm3. –> Surface area of the copper metal submerged in electrolyte – The surface area of the anode (copper metal piece) should be the same so that the amount of copper metal ionized at the same time would be constant, or else the rate of electroplating would be affected, hence affecting the mass of the copper metal deposited on the paper clip. It will be measured using a 20cm ruler, and be maintained at 0. 7cm2. Uncontrolled Variables:
Surface Area of the paper clip submerged in electrolyte – The surface area of the paper clip submerged into the electrolyte should be the same each time. The surface area of the paper clip affects how much copper metal will be electroplated onto the paper clip, which will determine the mass of the copper metal electroplated. However, the human eye is not accurate and the surface area of the paper clip submerged will vary slightly.
This will affect the mass of copper electroplated onto the paper clip. Apparatus List Apparatus Size Quantity 30V Power Supply – 1 Copper Strips – 3 Beaker 100cm3 1 Safety Pins- 10 Measuring Cylinder 25cm3 1 Safety Goggles – 1 Aqueous Copper Sulphate – 200cm3 Ruler 20cm 1 Retort Stand – 1 Stopwatch – 1 Crocodile Clips – 2 Apparatus Setup Diagram Method 1.
Lay out all apparatus, clean all of them thoroughly. 2. Using a 25cm3 measuring cylinder, pour 100cm3 of CuSO4 into the 100cm3 beaker. 3. Using a 20cm ruler, measure and mark the length and width of the copper metal that is to be submerged inside the CuSO4 solution. 4. Set up the 30V power supply and set it to 2V. Connect the crocodile clips and connect the copper metal piece to the positive terminal of the power supply. 5.
Weigh the paper clip on the electronic weighing scale for the initial mass of the paper clip. 6. Connect the paper clip to the crocodile clip and connect the wire to the negative terminal of the power supply. 7. Using a retort stand to prop the wire holding the copper metal piece up, and make sure the copper metal piece is submerged at the mark. Make sure that the crocodile clip is not submerged as well. 8. With the other wire, dip the paper clip into the solution, taking note of the amount of paper clip that is dipped in to make sure the surface area of paper clip exposed to the solution stays as constant as possible.