Faggot

Research Question
How does changing the concentration of Zn2+(aq) ions (0.2, 0.4, 0.6, 0.8, 1.0) (moldm-3) affect the voltage (V) of the voltaic cell consisting of Zinc and Copper half cells?
Aim
To see the relationship between increasing the concentration of Zinc ions and the voltage that is obtained from voltaic cell. The concentration of zinc ions can be directly manipulated by changing the concentration of a zinc sulphate aqueous solution, and the voltage will be measured using an electronic voltmeter.
Background Information
A voltaic cell produces electrical energy as a result of a spontaneous redox process. The electron transfer characteristic of such a process is made to occur in two separate half-cells. Electrons released during an oxidation half-equation must flow through a wire or other external circuit before they can be accepted in a reduction half-equation. Consequently an electrical current is made to flow (Chem Ed)

Two half equations could be written based on the voltaic cell that was shown as Figure 1. These two half equations are stated below:-
Zn(S)→Zn2+(aq)+2e-
Cu2+(aq)+2e-→Cu(s)
Furthermore, by combing these two half equation a final equation could be written. This final equation is shown below:-
ZnS+Cu2+(aq)→Zn2++Cu(s)
Hypothesis
If the concentration of Zn2+(aq) ions increases, the current of the voltaic cell also increases which this means the voltage also increases. This is because by increasing the concentration of Zn2+(aq), the number of ions increases as well thus more available ions result in higher chance of occurrence of oxidation or reduction reaction.

Independent Variable
Identify: Changing the concentration of Zn2+(aq) ions (0.2, 0.4, 0.6, 0.8 1.0) (moldm-3)
Reason and method of manipulation: In order to have reliable results from this lab 5 trials and 5 different concentrations were used. This increases the validity of the results that are going to be obtained from this lab. The concentration of Zn2+(aq) ions is manipulated by using 5 different concentrations of ZnSO4(aq).Since this is an ionic compound, it will dissolve in water; i.e. 1 mol of ZnSO4 will produce 1 mol of Zn2+ ions. Thus these 5 concentrations were used (0.2, 0.4, 0.6, 0.8 1.0) moldm-3. Only the concentration of Zn2+(aq) is going to be manipulated because only one variable is being tested. NO MAN the concentration of SO4 ions will change also but just say that we don’t take it into account and that it does not affect the experiment…
Dependent Variable
Identify: The voltage of the voltaic cell (V)
Reason & method of calculation: The electronic voltmeter is connected in parallel circuit to Zinc strip and Copper Zinc (what’s copper zinc) Say connected to the zinc and copper electrodes. The voltmeter reads the current and shows the voltage. I’d remove this bit, looks a bit confusing because you’re mentioning current now.. Or make it sound clearer Next the voltage from all the 5 trials and 5 concentrations are going to be noted down. After that the average of the voltages will be calculated using the Mean formula which is shown below:-
X=i=1nXin
Next the standard deviation is going to be calculated in order to see how far are the numbers are from the mean. The formula for standard deviation is mentioned below:-
∑(X-X)2(n-1)

Where:-
X= Each score
X= The mean of the score n = Number of values
∑= Sum across the values

Controlled Variable Table 1: Controlled Variable | Aspect | Why it is going to be controlled? | How it is going to be controlled? | Temperature of solutions of Zinc sulphate and Copper sulphate | Increasing the temperature decreases the voltage. That is because the current cannot reach equilibrium in higher temperature, therefore by decreasing the voltage the system maintains the equilibrium (Nihil Nonscio) Thus both solutions should have the same temperature in order to have a fair experiment. | The solutions will be requested to have the standard temperature which is 273 K (umm no, 273 K = 0 celsius LOL). Next using a thermometer the temperature could be measured. If the temperatures are not the same, incubators could be used to find (to set the temp not to find?) the appropriate temperature for the solutions. | Time of the voltage taken | It is important to have the same time for all the 5 trials. This is because when one trial is given more time, the ions would have more time to react and flow as currents therefore it is important to use the same time for all the 5 trials. | This is going to be controlled by deciding a specific time interval for example 60 seconds. The time can be taken down by a stopwatch. This way the specific time could be counted and controlled. | Salt bridge | A salt bridge allows the flow of ions to maintain a balance in charge between the oxidation and reduction vessels while keeping the contents of each separate. If no salt bridge were used, this charge difference would prevent further flow of electrons (Paula Atksin, Physical Chemistry for the Life Sciences) Therefore different salt bridges have different capacity to carry charges. Using the same salt bridge carries the same charge that is why it should be controlled.Since salt bridge consists of filter paper soaked in potassium chloride solution, make sure volume of potassium chloride is constant when soaking filter paper. And use same filter paper because amount of absorption will be different otherwise. | Using a specific salt bridge such as Potassium Chloride can control this aspect. Potassium Chloride is generally used as a salt bridge in voltaic cells.Use same volume of potassium chloride and same filter paper or whatever that thing is called | Volume of solutions of Zinc sulphate and Copper sulphate | Having more volume of a solution result in more number of ions which means a higher voltage thus it is important to keep the volume the same. | A volume of 300 cm3 (±0.1) is going to be used in this experiment for both solutions in order to keep volume constant. | Concentration of Cu2+(aq) | Since only one variable is going to be tested (different concentration of Zn2+(aq), the concentration of Cu2+(aq) should be constant. Having different concentration of Cu2+(aq) could change the voltage which therefore should be controlled. | This is going to be controlled by setting a specific concentration for Cu2+(aq). The concentration used for Cu2+(aq) is 1.0 (moldm. This concentration of Cu2+(aq) is going to be used throughout the 5 trials. | Same electrodes should be used? | | |

Apparatus * Graduated Cylinder 50 cm3x 2 (±0.25) * Copper Electrode 3 cm x 2 cm, x 25 * Zinc Electrode 3 cm x 2 cm, x 25 * Zinc Sulphate Solution 300 cm3x 25 (±0.1) Don’t put uncertainty here, just put for the instrumental uncertainty * Copper Sulphate Solution 300 cm3x 25 (±0.1) here also don’t put, its just confusing and not even needed * Digital Voltmeter x 1 (±0.2) * Potassium Chloride filter paper (salt bridge) x 25 * Connecting wires x 2 * Alligator Clips x 2 * Thermometer x 1 (±0.1) * Incubator x 1 * Beaker 400 cm3x 2 (±0.25) whats this? Uncertainty of what? * Stopwatch x 1 (±0.05 s) Instrumental uncertainty so say 0.01 not 0.05… and put units
Protocol Diagram

Safety Precautions * Tie your hair back if you have long hair * Do not consume any of the solutions * Do not run around the room while the experiment is going on … really colloquial but okay
Method
1. Measure the temperature of the solutions using a thermometer to make sure they have standard room temperature (273 K NO MAN). If not, place the solutions in the incubator until the appropriate temperature is obtained 2. Measure 300 cm3 of 1.0 (moldm-3)of Copper Sulphate solution using a 50 cm3 graduated cylinder and next pour it in the 400 cm beaker 3. Measure 300 cm3 of 0.2 (moldm-3) Zinc Sulphate solution using a 50 cm3 graduated cylinder and next pour it in the 400 cm3 beaker 4. Attack (attack the alligators? Why?) the alligator clips to the connecting wires and next attach the alligator clip to the 3 cm x 2 cm Copper electrode and attach the connecting wire to the voltmeter 5. Attack (attack them again?) the alligator clips to the connecting wires and next attach the alligator clip to the 3 cm x 2 cm Zinc electrode and attach the connecting wire to the voltmeter 6. Place the copper electrode in the copper sulphate solution and zinc sulphate in zinc sulphate solution 7. Make a U shape out of the Potassium Chloride filter paper and put one end in copper sulphate solution and the other in zinc sulphate solution (you need to say: soak filter paper in potassium chloride (1 moldm-3) then place in solutions) 8. Using stopwatch measure 5 minutes and next write down the voltage that is shown in the voltmeter 9. Repeat step 1-8 four more times so in total there are 5 trials 10. Repeat step 1-9 with the other four concentration of zinc sulphate solution (0.4, 0.6, 0.8 1.0) (moldm
*The volume of the solutions are going to be controlled by measuring 300 cm3 of each solution using a 50 cm3 graduated cylinder. The temperature is going to be controlled using a thermometer and incubator. The concentration of copper sulphate is going to be controlled by using only 1.0 M (say moldm-3, not M). The time is going to be controlled using a stopwatch timing 5 minutes for each trial. The only salt bridge used will be filter paper soaked in a constant volume of Potassium Chloride so that is going to be controlled as well.
Data Collection
Raw Data: Table 2: Changing the concentration of Zinc Sulphate solution (0.2, 0.4, 0.6, 0.8, 1.0) M in the voltaic cell in order to see the voltage | Concentration of Zinc Sulphate Solution (moldm-3) | Voltage obtained from Voltaic Cell (V) | | Trial | | 1 | 2 | 3 | 4 | 5 | 0.2 | | | | | | 0.4 | | | | | | 0.6 | | | | | | 0.8 | | | | | | 1.0 | | | | | |

**Qualitative data will be observed during the experiment and will be noted down in the lab.
There are going to be 5 different concentrations and 5 different trials for each concentration in order to increase the validity of the results obtained in this lab.
Data Processing:
The voltage from all the 5 trials and 5 concentrations are going to be noted down. After that the average of the voltages will be calculated using the Mean formula which is shown below:-
X=i=1nXin
Next the standard deviation is going to be calculated in order to see how far are the numbers are from the mean. The formula for standard deviation is mentioned below:-
∑(X-X)2(n-1)
After that error uncertainty is going to be calculated. This is done to deduce how much of the percentage error was caused by the inaccuracy of the apparatus. The formula for error uncertainty is mentioned below:-
UncertaintyMeasurement×100
Next the percentage error could be determined. There are published values either on the internet or on the data booklet. Those values are called ‘Accepted Values’. The formula for percentage error is shown below:-
Accepted value-Experimental valueAccepted value×100

Representation of Data:
The graph from the processed data should be drawn. That means the average values and standard deviation should be drawn. The graph should look like Graph 1. This is shown below:-
Line graph showing conc (IV) on x-axis and voltage (DV) on y axis
Straight line because directly proportional

Bibliography 1. Ed, Chem. "Galvanic Cells." Chemistry. N.p., n.d. Web. 1 Mar. 2013. 2. Nonscio, Nihil. "Galvanic Cells." Yahoo Answers. N.p., n.d. Web. 2 Mar. 2013 3. Atkins, P. de Paula, J. Physical Chemistry for the Life Sciences. pg 209-225. 2006. Oxford Univeristy Press. New York. N.p., n.d. Web. 2 Mar. 2013.

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[ 1 ]. Ed, Chem. "Galvanic Cells." Chemistry. N.p., n.d. Web. 1 Mar. 2013.
[ 2 ]. Nonscio, Nihil. "Galvanic Cells." Yahoo Answers. N.p., n.d. Web. 2 Mar. 2013.
[ 3 ]. Atkins, P. de Paula, J. Physical Chemistry for the Life Sciences. pg 209-225. 2006. Oxford Univeristy Press. New York. N.p., n.d. Web. 2 Mar. 2013.

Bibliography: 1. Ed, Chem. "Galvanic Cells." Chemistry. N.p., n.d. Web. 1 Mar. 2013. 2. Nonscio, Nihil. "Galvanic Cells." Yahoo Answers. N.p., n.d. Web. 2 Mar. 2013 3. Atkins, P. de Paula, J. Physical Chemistry for the Life Sciences. pg 209-225. 2006. Oxford Univeristy Press. New York. N.p., n.d. Web. 2 Mar. 2013. -------------------------------------------- [ 1 ]. Ed, Chem. "Galvanic Cells." Chemistry. N.p., n.d. Web. 1 Mar. 2013. [ 2 ]. Nonscio, Nihil. "Galvanic Cells." Yahoo Answers. N.p., n.d. Web. 2 Mar. 2013. [ 3 ]. Atkins, P. de Paula, J. Physical Chemistry for the Life Sciences. pg 209-225. 2006. Oxford Univeristy Press. New York. N.p., n.d. Web. 2 Mar. 2013.