Report 2 Electrolysis
Report 2 Electrolysis
Report 2 Electrolysis
Exp.3 Electrolysis
Exp.4: Electro deposition of copper through the
electrolysis of Copper(II) solution
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Abstract
Electrolytic cell and the process of Electrolysis, this aim is approached by using the
Hoffmann Voltammeter device and brine (sodium chloride) solution included and to
observe the changes happen in the solution, relating these observations with the
chemical reactions happen due to the electrical current. As for the experiment of
how to calculate the Copper lose and gain on the Anode and Cathode electrodes by
applying a specific amount of current during the process. By using Faraday's law it
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Table of Contents
Abstract ...................................................................................................................2
Introduction .............................................................................................................4
A.Electrolysis of Sodium Chloride solution........... ..........................................................4
B.Electro deposition of copper through the electrolysis of Copper(II) solution...................8
B.Faraday's Second Law of Electrolysis........ .............................................................. 12
Experimental Method and Procedure ........................................................................ 14
Experimental results ................................................................................................ 15
Discussion .............................................................................................................. 17
Sources of error ...................................................................................................... 18
Bibliography ............................................................................................................. 19
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Introduction
The part or branch in chemistry that deals with the relationship between electricity
and chemical reactions is called Electrochemistry. It deals with the chemical changes
electrolytes. Electrochemical cells are the device that works by converting electrical
energy into chemical energy or vice versa. According to the activity takes place in the
devices, they are divided into two categories which are: Electrolyte cells and Galvanic
cells. (D.Ebbing, 2008) In our case the electrolytic cells will be taken in consideration
for this experiment. Electrolytic cells are the devices that aims to occur chemical
Electrolysis is the process in which separating the elements and compounds bonded to
each by the passage of electrical current through them. The salt is an ionic compound
which is dissolved with a suitable solvent, like water as the its own ions are avilable
in the liquid. An electrical current is utilized between two inert electrodes (Graphite)
sunken into the liquid. The cathode is the (-ve) charged electrode and the anode is the
(+ve) charged electrode. As each electrode attracts the ions of the opposite charge,
(+ve) charged ions (cations) heads to the cathode while the (-ve) charged ions
(anions) heads to the anode. The electrical power supply aims to produce energy to
separate the ions and makes them assemble at the particular electrode. At the
investigation, the ions release or absorbs the electrons that result the formation of
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The above apparatus is called Hofmann Voltammeter which was used in the lab to
perform the electrolysis process, by using tubes like burettes and Graphite electrodes.
The device is filled with aqueous NaCl (brine solution) which is the electrolyte, to
allow the gas produced during the process, both taps at the top are opened. As for the
two types:
aqueous solutions and their values of conductance are very high. For example
solutions and the conductance values are very low. There is an equilibrium
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state between the ions and their undissociated molecules that exists in the
HCOOH.
The NaCl electrolyte solution supply a high concentration of (sodium) ions Na+ and
also chloride ions (Cl– ) to hold the current during the process. Firstly, there are only
marks of hydrogen ions (H+) and hydroxide ions (OH–) from the self ionization of
H2O. The sodium chloride solution is conservatively concentrated NaCl solution with
(Graphite) gives an equal volumes of (H) gas (hydrogen ions H+ discharged at the
negative cathode) and (Cl) gas (chloride ions Cl– discharged at the positive anode)
with NaOH kept in solution. This process (electrolysis) will only occurs when
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The electrolysis of sodium chloride half-equations is divided into two parts, one in
the negative part of the process and the other at the positive part. (Vairam, 2013)
The negative (–ve) cathode electrode attract the (Na+) from the solution and (H+ )
ions from H2O. Only the ions of hydrogen are discharged at the cathode. As the
reactivity of the metal increases, the readily of ions is decreased on the surface of the
electrode. The ions of hydrogen are reduced by the electron (e–) gain to be able to
form hydrogen molecules at the (-ve) electrode which attract positive ions (as
discussed before).
As long as the sodium ions are important, there isn't any significant change happens to
them. However, if sodium was released , a reaction between sodium and water would
happen to result hydrogen, as like as the product resulted from the reduction of the
hydrogen ion.
for the electrolysis process of NaCl solution, The (+) anode attracts the (-) hydroxide
(OH– ) ions from H2O and chloride (Cl– ) ions from NaCl. Just only the (Cl) ion is
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Ions of chloride are oxidized by the electron loss to outcome chlorine molecules at
the (+) electrode which attracts (-ve) ions (as discussed before). (Vairam, 2013)
thin layer of metal ion surrounding it. The metal important concept is to be coated, is
done by the cathode electrode in an electrolytic cell. (J, 2007) The cell which used in
the electroplating includes an electrolyte of aqueous solution that has a rationally high
The cell anode electrode is generally a piece of metal to be plated from solution; this
gives the chance to the anode reaction of metal dissolution to substitute the metal ion
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The electrodes product from the electrolysis process of copper sulfate with inert
The (-) cathode electrode entice (Cu2+)ions from the copper sulfate (electrolyte), and
H+ ions from H2O. Only the (Cu) ion is discharged, being deduced to copper metal.
As the metal is less reactive, the more readily its own ion is reduced on the surface of
the electrode. The copper deposits forms as the (+) copper ions are enticed to the
(-)(cathode) electrode.
Positive ions reduced by the electron gain. The effects of hydrogen ions aren't
discharged, that explain why there isn't any gas gathered above the (-) electrode.
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The (+) anode electrode reaction with the copper electrode. It is the (Cu) anode that
makes the critical difference than electrolyzing the copper sulfate solution
(electrolyte) with an inert Graphite electrode. The (-) sulphate ions (SO42- ) from
copper sulfate or from the traces of hydroxide ions OH– from H2O are gathered to the
(+) electrode. But the sulfate ion and the hydroxide ions are very stable as nothing
discharge the (Cu2+ ) copper ions. An oxidation of the electrode reaction at the (+)
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Faraday's law of Electrolysis
Whenever the electrolyte such as metal sulfate is diluted in H2O, its molecules divided
into (+ve) and (-ve) ions. The (+ve) ions or metals ions heads to the electrodes
connected with (-ve) side of the battery, where these (+ve) ions takes electrons from
it, in order to be pure metal atom and get settle on the electrode. Whilst (-ve) ions or
moves toward the electrode connected with (+ve) terminal of the battery as these (-)
ions withdraws their extra electrons to be SO4 radical. (Ramesh, 2013) Since (SO4 )
cannot exist in electrically neutral state, they will attack metallic (+ve) electrode to
result a formation of metallic sulfate which will experience dissolve in the H2O. The
From the previous explanation, it is obvious that the movement of the current through
the battery circuit completely depends on how many electrons are transferred from (-
ve) electrode or the cathode electrode to (+ve) metallic ions or cations. If the cations
contains valency of two such as (Cu++ ) then for each cation, there should be 2
electrons allocated from cathode to cation. Its known that every electron has (-ve)
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electrical charge having value of (− 1.602 X 10 ) Coulombs and say it is (- e). So
for configuration of every (Cu) atom on the cathode electrode, there would be (- 2.e)
charge transfers from the cathode to cation. As for (t) time there would be total (n)
which is number of copper atoms settle on the cathode, so the total charge which is
transferred would be (- 2.n.e) Coulombs. Mass (m) of the deposited copper is clearley
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a function of the number of atoms settled. Consequently, it can be predicted that the
(m) mass of the settled (Cu) has a relation of directly proportional to the quantity of
electrical charge that moves through the electrolyte. According to the previous, mass
electrolyte. Faraday's First Law of Electrolysis claims that , Referring to this law, the
proportional to the quantity of electricity (coulombs) passes through it. i.e. mass of
chemical deposition.
Until now, it was discussed that the mass (m) of the chemical deposited resulted from
the electrolysis is proportional to the quantity of electricity that moves through the
electrolyte. The mass (m) of the chemical set because of electrolysis isn't only
proportional to the quantity of electricity moves through the electrolyte, its also count
on several other factor. Each substance will have its atomic weight. So for same(n)
number of atoms, unlike substances will have different (m) mass. Moreover, the
number of atoms set on the electrodes also count on their value of valency. If valency
is higher, so for same amount of electricity, number of deposited atoms will decrease
whereas if valency is lower, then for same quantity of electricity, more number of
atoms to be set. So, for the same quantity of electricity or charge moves through
unlike electrolytes, the mass (m) of settled chemicals is directly proportional to the
atomic weight and inversely proportional relation to its valency. Faraday's second law
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claims that, when the same quantity of electricity passes through varies electrolytes,
the mass (m) of the substances deposited are proportional to their particular chemical
substance can be deduced by Faraday’s laws and it is stated as the weight of that sub
tenancy which combine with or displace unit weight of H2. The chemical equivalent
of H2 is, thus, unity. As valency of the substance is equal to the number (n) of
H2atoms, which it can substitute or with which it can merge, the chemical equivalent
of a substance, subsequently may be stated as the ratio of its atomic weight to its
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Experimental Method and Procedure
You are provided with 1M NaCl solution, a U-shaped tube, two graphite electrodes, a
power supply, an ammeter, and a universal indicator
1- Add the salt solution in the U-tube.
3- Once the ammeter shows reading you will notice that bubbles commenced to form
at one of the electrodes, then after some time they will begin to form at the other.
4- Around one of the electrodes the color of the indicator will change into deep blue,
while at the other one the color of the indicator will be bleached.
5- Record all of your observations in the following table, completing it with the
necessary equations.
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Experimental results
A. For Electrolysis
During the experiment of electrolysis, on switching the curcit on, there were changes
in color and bubbles formation was observed, these observations conclude and
demonstrates information and reasons. The table below includes the observations and
reasons supported with equation:
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B. For Electro deposition of copper
In order to be able to calculate the thickness (x) of the plate, there are several
Q=I*t
W =I * t * e/ F
W = ρ * A* x
Where
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Discussion
A. For Electrolysis
the brine solution (sodium chloride), there were changes observed in the experiment
which was deduced previously in the Experimental results. The reason behind
showing bubbles at the Cathode part is because the ions of hydrogen are reduced by
the electron (e–) gain to be able to form hydrogen molecules at the (-ve) electrode
which attract positive ions. As for the other part, Ions of chloride are oxidized by the
electron loss to outcome chlorine molecules at the (+) electrode which attracts (-ve)
ions.
To conclude it all without any exaggerations, this experiment object to present the
previously, the movements of ions between the anode and the cathode electrodes.
Moreover, Faraday's law of claims that the mass of the copper produced at an
electrode during the process is directly proportional to the number of moles (n) of
electrons the quantity of electricity allocated at that electrode, which was proofed by
the experimental calculations. Also, the number of Faradays of the electric charge
excess primary charges on that ion. Both hypothesis are Oftenly considered as
different laws, but still support each other to demonstrate the correct process of the
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Sources of error
1. The devices used to take readings such as voltmeter are more likely needed to
2. The apparatus/ device used in the experiment like the Hoffman Voltammeter
could be unclean and not washed well, which leads to create an error.
experiment one of the students used stop watch to obtain the time (t) taken,
this incident will mostly have error on estimating the accurate value of time.
4. The copper plates used for the Electro deposition experiment could be rusty
due to storing them for a long period. Consequently, this surely will show a
5. In the laboratory, a commonly mistakes run across for example pereparing the
concentration of the solution with wrong values, which does not match the
experimental numbers.
6. The instruments used in the electrolysis experiment wasnt prepared well, there
7. There are devices such as the device used to balance the plate could be out to
date and need to be replaced with brand new devices, to avoid error in the
experimental results.
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Bibliography
Ramesh, D. S. (2013). Engineering Chemistry. New Delhi: John Wiley & Sons Ltd.
Vairam, D. S. (2013). Engineering Chemistry. New Delhi : John Wiley & Sons Ltd.
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