The main problem with circuits is the resistance and this can affect many areas of the experiment and be affected by factors in the experiment. The factors I will be measuring are temperature and material of the circuit. The temperature rise increases the energy (enthalpy) of the material and thus shows the relationship of this energy to the electrical energy. Material of which the circuit is made also affects energy flow. Usually this material is a metal because metals have a sea of electrons and can conduct electricity well. Also in each metal there is a different amount of free electrons and the more electrons the more efficient the energy will flow.
Hypothesis:
Electrochemical batteries the standard electrode potentials are used to find the voltage of a circuit. According to the data the voltages of the batteries used are as follows:
According to the data the lowest voltages are of the Pb and Sn and the highest ones being Mg and Cu (half cells) for the lowest power expected there needs to be a very low enthalpy and for the highest, a high enthalpy respectively. This means that as the temperature is increasing the particles in the metal start to move faster and making the energy move faster therefore increasing the power. We can also alter the material and thus there will be a change in amount of free electrons. This in turn increases power. Also the size of the particles affect the distance the electrons have to travel so with a greater distance it is more likely to decrease.
Variables:
The battery:
Dependent: Reactions
Independent: power measured in Watts
Controlled: concentration, circuit, temperature, pressure, concentration
The circuit:
Dependent: Change in enthalpy measured in Joules; material
Independent: power measured in Watts
Controlled: pressure, the wires, battery, material, temperature, concentration
Planning B:
Materials:
Galvanic Cell:
- 1 M 50 ml ZnSO4
- 1 M 50 ml MgSO4
- 1 M 50 ml PbSO4
- 1 M 50 ml SnSO4
- 1 M 50 ml CuSO4
- 1 M 50 ml FeSO4
- Strips of Zinc, Magnesium, Lead, Tin, Copper, Iron
- A salt bridge
- 2 x 100ml beakers
The Circuit:
- Ammeter
- Hot plate
- Thermometer
- 1.0 mol Strips of Magnesium, Iron, Copper, Zinc, Lead and Tin
- Wires
- Voltmeter
Procedure:
- Keep the surroundings constant (pressure and temperature)
- Next make a Galvanic Cell by Pouring 50 ml of 1 M ZnSO4 into one beaker and 50 ml of 1 M CuSO4 into another.
- Put Zinc and Copper into corresponding beakers
- Connect the beakers with a salt bridge
- Measure the voltage and the current (voltmeter, ammeter) by attaching them to the metal strips
- Calculate the power
- Repeat steps 1 to 5 but change the metals and sulphates according to the data table in hypothesis.
- Build a circuit (using wires and a constant power source)
- place a strip of 1 mol Magnesium in the middle of the circuit and attach it
- Calculate the power
- Raise the temperature by 10º C
- Calculate the enthalpy
- Find the power
-
Repeat the process from step 10 → 14 another 4 times
- Record data
