The purpose is to place the relationship between the concentration of H2SO4 solution and the current of Cu-Zn Gur cell. Hypothesis
My hypothesis is that the greater the concentration of sulphuric acid the bigger the current of the Gur cell. In a Gur cell. chemical energy is concerted to electrical though the oxidization and decrease happen on the electrodes. Current will non flux through pure H2O. There must be electrolytes dissolved in it before electricity can go through through it. When the concentration of sulphuric acid is increased. the figure of ions is increased. There will be more ion transporting electric charge. Then. current is increased. Introduction and Background
This is the Cu-Zn Gur cell used in the experiment. Zinc has higher responsiveness and it is more likely to loss negatrons. Therefore. negatrons flow from Zn electrode to Cu electrode. Copper band is the positive electrode. Zinc band is the negative electrode. Chemical reaction happened on each terminus:
Positive terminus: Zn-2e->Zn2+
Negative terminus: 2H+2e->H2
It is assumed that bubbles ( H gas ) will come out from Cu electrode.
It is assumed that Zn and Cu chevrons are pure.
Categorization of variables
Current of the Gur cell
Concentration of sulphuric acerb solution
Size of the Cu and Zn chevrons
Material of the electrodes
Distance between the electrodes during reaction
Volume and temperature of sulphuric acerb solution
Materials and Apparatus
1cm?4cm Cupper chevrons
1cm?4cm Zinc chevrons
1 Ammeter ( ±0. 015 )
2 Beakers ( 50mL )
9molL-1 H2SO4 ( ±1 % )
1 Cylinder ( 25±0. 1mL )
Cystosepiment with two holes
1. Dilute the 9molL-1 H2SO4 by pouring 5mL sulphuric acerb solution and 35 mL H2O in a beaker and splash. 2. Use two wires to link the Cu band and Zn band to the ammeter. Copper band is the positive electrode and should be connected to the positive electrode with maximal warp of 0. 6A. Zinc band should link to the negative terminus. 3. Penetrate the chevrons into holes of the cystosepiment to repair their place in the electrolyte. Minimize the place between the two chevrons in order to maximise the current of the Gur cell. but do non allow them touch. 4. When you foremost out the electrodes in the electrolyte. the arrow of ammeter will beckon violently. After some clip. enter the figure ampere before the pointer start falling to the original point. 5. Repeat measure 1 to 4 for tree clip.
6. Repeat measure 1 to 5 with more diluted sulphuric acid. Control the entire 40mL volume of solution. Increase the volume of H2O and cut down the volume of original 9molL-1 H2SO4.
Rough Collected Data
Concentration of H2SO4 solution: 9molL-1
Volume of H2SO4: 40mL
The solutions were supplied by the instructor with the given mistake of 1 % . A cylinder was used to present the solutions ; hence the mistake was estimated at 0. 2 cm3.
| Volume of H2SO4 ( ±0. 2mL ) | Volume of H2O ( ±0. 2mL ) | Volume of diluted H2SO4 ( ±1 % milliliter ) | 1| 5| 35| 40|
2| 4| 36| 40|
3| 3| 37| 40|
4| 2| 38| 40|
5| 1| 39| 40|
| Concentration of diluted H2SO4 ( molL-1 ) |
1| 1. 125|
2| 0. 900|
3| 0. 675|
4| 0. 450|
5| 0. 023|
| electronic current ( A ) ( ±0. 015A ) | Average electronic current ( A ) ( ±0. 015A ) | 1| 0. 21| 0. 22| 0. 22| 0. 217|
2| 0. 18| 0. 18| 0. 18| 0. 180|
3| 0. 14| 0. 15| 0. 14| 0. 143|
4| 0. 12| 0. 12| 0. 12| 0. 120|
5| 0. 11| 0. 09| 0. 11| 0. 103|
| Concentration of diluted H2SO4| Electronic Current ( A ) ( ±0. 015A ) | 1| 1. 125| 0. 217|
2| 0. 900| 0. 180|
3| 0. 675| 0. 143|
4| 0. 450| 0. 120|
5| 0. 023| 0. 103|
When I put the electrodes in 1. 125 molL-1 H2SO4 solution. the reaction is violently. Many bubbles formed at the Cu electrode with pungent odor. After the reaction. the colour of Zn band changed from Ag Grey to black. The colour of Cu band became darker brown. When the H2SO4 solution is diluted. the alteration of the stripes’ colour becomes slighter. Figure 1: graph concentration of H2SO4 solution versus electronic current. Figure 1: graph concentration of H2SO4 solution versus electronic current.
This figure shows the relationship between concentration of electrolyte H2SO4 solution and the electronic current of this Cu-Zn Gur cell. The electronic current additions with the concentration electrolyte.
Samples of computation
vdiluted H2SO4=voriginal H2SO4+vwater
=5±0. 2+35±0. 2
= ( 5+35 ) ±0. 2+0. 2
= ( 40±0. 4 ) milliliter
= ( 0. 04±1 % ) Liter
nH2SO4of diluted H2SO4solution=c?v
= ( 9±1 % ) ? ( 5±0. 2 ) ?10-3
= ( 9±1 % ) ? ( 5±0. 25 ) ?10-3
= ( 9±1 % ) ? ( 5±12. 5 % ) ?10-3
= ( 0. 045±13. 5 % ) mol
cdiluted H2SO4=nH2SO4of diluted H2SO4solutionvdiluted H2SO4
=0. 045mol ( ±13. 5 % ) 0. 04L ( ±1 % )
= ( 1. 125±14. 5 % ) molL-1
Decision and Evaluation
The experiment shows that the current of Cu-Zn Gur cell will increase with the concentration of electrolyte H2SO4 solution. It is because that when the concentration of sulphuric acid is increased. the figure of ions is increased. There will be more ions transporting electric charge. Then. electric current is increased. There are a figure of alterations which can assist to better my experiment and makes the consequences more dependable. For illustration. the ammeter I used in this experiment is non so accurate. A better machine with smaller uncertainness can do the consequences more dependable. When H2O and sulphuric acid solution are added together. heat is released. It may be better to mensurate the temperature of the assorted solution and waiting for the temperature to fall to the room temperature.
Then the consequences will be more accurate. The Cu and Zn chevrons are non pure plenty. Impurity in the chevrons may devour some of the current of the Gur cell. The consequence will be less than what it should be. Purer chevrons can better the experiment consequences. During the experiment. pungent odor is released. It is because that some acerb mist came out with the H gas. There may be some toxic substance in the mist. To better this state of affairs. a porous board wetted by NaCO3 solution should be used to repair the electrodes alternatively of the cystosepiment. A porous board can allow the H gas come out and basic NaCO3 solution in it can respond with the acidic drosss in the gas and cut down the pungent odor.