Chapter 14 - Electrochemical Cells Flashcards
Why are electric vehicles better than gas ones?
Because they are more efficient and create less pollution. They are also nearly silent and don’t need too much maintenance.
What is the main reason that electric cars aren’t around yet?
There is no powerful, lightweight, inexpensive battery.
Who invented the first electric cell?
Volta, inspired by Galvani.
What does an electric cell do?
Converts chemical energy into electrical energy.
What is a battery?
A group of two or more cells.
What is brine?
Aqueous sodium chloride.
What was Volta’s first battery like?
It was bowls of brine with copper and zinc connected going through each one. Then it was layers of copper, paper soaked in salt solution, and then zinc (a voltaic pile).
Basic components of an electric cell:
Two electrodes and one electrolyte.
What is an electrode?
A solid electrical conductor.
What is an electrolyte?
Aqueous electrical conductor.
In an electric cell or battery, the _______ is the positive electrode and the ______ is the negative electrode.
Cathode; anode.
Electricity is the flow of…
Electrons.
Electrons move from the ___ to the ____.
Anode to the cathode.
What do the electrons move through?
An external circuit like a wire.
What is a voltmeter?
Used to measure energy difference between any 2 points in an electric circuit.
What is electrical potential difference?
Energy difference per unit charge.
Is voltage effected by the size of a battery or cell?
No.
The voltage of a cell mainly depends on:
the chemical composition of the reactants in the cell.
Electric current is measured by
an ammeter (in amperes).
The larger the electric cell, the greater…
the current that can be produced.
The charge transferred by a cell or battery is measured by…
Coloumbs.
Power of a cell is measured in…
watts.
Energy density is measured as
Joules/kilogram
Which came first, the discovery of cells or the discovery of electrons?
Cells.
What kind of cell is commonly referred to as a “dry cell?”
A zinc chloride cell.
What is a primary cell?
A cell that cannot be recharged.
Types of primary cells?
Dry cell, alkaline dry cell, mercury cell.
Types of secondary cells?
Ni-Cd cell, lead-acid cell.
Types of fuel cells?
Hydrogen-oxygen cell, aluminium air-cell.
How is a secondary cell recharged?
Using electricity to reverse the chemical reaction that occurs when electricity is produced by the cell.
What type of battery is in a typical car battery?
A lead-acid cell.
Recharging a cell is not spontaneous because…
it takes energy.
How does a fuel cell work?
They produce electricity by the reaction of a fuel that is continuously supplied to keep the cell operating.
Are fuel cells more efficient than methods that produce electricity by the burning of fossil fuels?
Yes.
Basic description of an aluminium-air cell:
Air is pumped in an oxygen is reduced at the cathode while aluminium is oxidized at the anode. Has been developed to be used in electric cars.
What are galvanic cells?
Cells adapted for scientific study.
What is a porous boundary?
It separates the two electrolytes in a voltaic cell. Allows ions through, though, through the salt bridge.
What does a half-cell consist of?
One electrode and one electrolyte.
What does a single line (I) represent in cell notation?
A phase boundary.
What does a double line (II) represent in cell notation?
A physical boundary.
What does a voltaic cell consist of?
Two half cells separated by a porous boundary.
The SRA always undergoes an oxidation at the
anode.
The SOA always undergoes a reduction at the
cathode.
What does the salt bridge do?
It makes sure that the solutions remain electrically neutral by having cations move to the cathode and anions move to the anode.
What is an inert electrode and what does it do?
An inert electrode is a solid conductor does not interfere or react with the cell reaction. Inert electrodes provide a pace for a location to connect a wire and a surface on which a half reaction can occur. Usually platinum or carbon.
Cell notation format:
anode I electrolyte II electrolyte I cathode
What is a standard cell?
A voltaic cell in which each half-cell contains all entities shown in the half reaction at SATP conditions with a concentration of 1.0mol/L for the aqueous solutions.
What is the standard cell potential E°?
The maximum cell potential difference (voltage) in standard conditions. This is what a voltmeter measures.
What is standard reduction potential?
The ability of a standard half-cell to attract electrons , thus undergoing reduction.
How do you calculate standard cell potential?
Cathode - anode
What is a reference cell?
Hydrogen, at zero volts.
If cell potential is positive, the reaction is
spontaneous.
Does voltage change as a battery gets older?
Yes, it decreases.
When electrons flow from the anode to the cathode, it is potential energy to…
kinetic energy.
What sort of placement on a redox table will get a metal oxidized?
If it is a strong reducing metal and below any reaction with oxygen.
What is required for the corrosion of iron?
Oxygen and water.
What can accelerate the rusting of iron?
Acidic solutions, electrolytes, mechanical stresses, and less active metals. Salt.
Cathodic protection
Iron is forced to become the cathode by supplying it with electrons using an impressed current (electric current forced to flow to the iron) or a sacrificial anode. (a metal more easily oxidized than iron).
Which is spontaneous, an electrochemical cell or an electrolytic cell?
Electrochemical.
Basic components of an electrolytic cell:
Two electrodes, an electrolyte, and a battery.
What is electrolysis?
The process of supplying electrical energy to force a nonspontaneous reaction to occur.
Does an electrolytic cell have a positive or negative cathode?
Negative, opposite of an electrochemical cell.
The Chloride Analomy
Chlorine gas is produced instead of instead of oxygen gas in situations where chloride and water are the only reducing agents present.
Chlor-Alkali Process
The electrolysis of brine to produce chlorine, hydrogen, and sodium hydroxide. Chlorine here is the reducing agent anode. Water is the cathode.
Electrorefining
Uses an electrolytic cell to have pure substance build up on the cathode. Copper is reduced at the cathode.
Electrowinning
Uses an electrolytic cell to reduce metal cations at the cathode.
Q =
I x T
n e- =
Q/F
Cell stoichiometry - what is the wanted and what is the given?
Depends, but it will be found in the half reaction as the coefficient.
