A
What is oxidation and where does it occur?
It is the loss of electrons and it occurs in the negative electrode, the anode.
What is electrochemistry?
Electrochemistry is the conversion of chemical energy to electrical energy and electrical energy to chemical energy.
What are redox reactions?
Simultanious oxidation and reduction
If two Fe metal is in FeSO4 solution of different concentration, then it is called as?
Concentration cell
What is the oxidation number of oxygen?
-2
List the differences between oxidation and reduction
Oxidation:Loss of electrons,Addition of oxygen,Increase on oxidation state,Release electrons,Increase of positive charge of a chemical species,Takes place in the anode
Reduction:Gain of electrons,Removal of oxygen,Decrease on oxidation state,Obtains electrons,Increase of negative charge of a chemical species,Takes place in the cathode
If a cell is constructed by dipping Cu in CuSO4 solution of 1M concentation. What is the potential produced at 298K?
+0.34V
Contrast an electrolytic and a galvanic cell
An electrolytic cell requires current and non spontaneous reactions occur on them. Whereas spontaneous reactions occur in a galvanic cell, a cell that generates current.
A device where CHemical Energy is converted to Electrical Energy is called as
Galvanic cell
What formula is used to calculate cell potential?
Ecell = Ered - Eox
How is electrochemistry applied inside a battery?
Batteries have one or more electrochemical cells which contain chemical energy that will be converted into electrical energy. Since electrochemistry is the conversion of chemical energy to electrical energy and electrical energy to chemical energy, electrochemistry can be found inside batteries.
What relationship is there between the amount of electrolytes and the voltage produced?
The more electrolytes, the higher voltage there is.
what would happen if a person tried to charge a regular alkaline battery (non rechargeable battery)?
When reversing the circuit, the battery might release hydrogen gas that could potentially lead to explosion.
which is the oxidizing agent in the following reaction: Zn + 2H+ → Zn2+ + H2
Hydrogen
Which is the oxidizing agent ? 2CaO → 2Ca + O2
Oxygen
evaluate and compare two different batteries, alkaline and non-alkaline batteries.
If we use a device powered by an alkaline battery and another powered by a non-alkaline battery for 24 hours, then the battery with more energy left will be the alkaline battery, because an alkaline battery is made of potassium hydroxide which makes it maintain power for a longer period and have larger capacity compared to a non-alkaline, normally made of zinc.
which combination of anode and cathode creates the best result. In the experiment they could choose iron (anode) and lithium (cathode), or iron (cathode) and lithium (anode).
A battery that uses lithium as the anode and iron as the cathode will show better results because iron has a higher reduction potential than lithium.
What are the half reactions for the following reaction: Fe2O3 + CO = Fe + CO2
R:C+2→ C+4 + 2e-
O:Fe+ 6e- → 2Fe
What would happen if a strip of silver is dropped in a solution of aluminum?
Since silver is lower in the activity series than aluminum, it is more easily oxidized, yet it is harder for it to oxidize an element such as aluminum that is lower in the activity series. Therefore, no reaction would occur.
Can you find the electrical cell potential in the following reaction? How did you do it? Reaction:
2Al3+(aq) + 3Cu(s) → 3Cu2+(aq) + 2Al(s)
2Al3+(aq) [3+] + 3Cu(s)[0] → 3Cu2+(aq)[2+] + 2Al(s)[0]
Oxidation= Cu [0] → [2+]
3Cu(s) → 3Cu2+(aq) + 2e-
Reduction= Al [+3]→ [0]
2Al3+(aq) + 2e- → 2Al(s)
EO= Eo red - Eo ox
EO= (-1.66)-(-0.34)
EO= -1.32 V
Non-spontaneous
Jimmy wants to determine by how much does a Lithium-Ion Battery lose its efficiency after 20 recharges. For his procedure, Jimmy first used an old Lithium-Ion battery from his broken phone. Jimmy only measured the voltage of the battery after 5 charges. After calculating the percent yield, he realized the battery was already 6.7% efficient. Because of this, Jimmy concluded that after 20 recharges a Lithium-Ion battery loses its efficiency by 100%. Evaluate Jimmy's Results, are they accurate? Can you create a better procedure?
Jimmy’s results are extremely inaccurate as there are many flaws in his procedure. The first flaw is that Jimmy used an already damaged and old Lithium-Ion battery. The second flaw is that Jimmy only measured the Battery’s voltage once. These two major flaws are what remove any validity from his results. In order to create a better procedure, Jimmy should use more than one fresh battery in order to account for error, he should measure the voltage of each battery at the beginning and periodically measure it every 2 to 5 recharges until he reaches 20. This will ensure that his data is accurate and correct.
Analyze the following result that was obtained from an experiment where the electric potential of batteries with different fruits was measured: A grape battery´s electric potential was tested and the voltage obtained was 0.2 volts dc. Where does the energy to create this amount of voltage come from? Where are the electrolytes? How is the electrical current generated and why?
In the experiment, there are 2 electrodes and one electrolyte. The electrode with the highest electronegativity (cathode), will gain the electrons from the anode. The electrons that are clumping up in the anode, will pass through the wire and travel from the anode to the cathode, but the protons are way too big to pass through the wire. This is why the electrolytes are used for. The protons will pass through the electrolytes. The electrolytes will oxidize the anode and positively charged ions will move into the solution. The electrons, now in the cathode, will take protons from the acid and reduce them.
why don’t copper and zinc create an electric current without the lemon?
Copper and zinc can’t go through a redox reaction alone because the electrons cannot flow, there is no channel to. The citric acid in the lemon acts as an electrolyte and allows the electrons to move freely, thus creating a battery.
How could you increase the electrical potential of a lemon battery to create a greater voltage?
To create a greater voltage in an experiment that is using a lemon as a battery, you could create a circuit that has more electrodes so the potential increases (more energy is produced).
Argue whether it is the anode or cathode what contributes more to the flow of electrons (electricity flow/current)
The anode contributes more because it is what provides the actual flow of electrons towards the cathode. Without the anode there would be no oxidation and flow of electrons in an electric circuit. These are the ones that react chemically and give electrons for the circuit to work.