Chem Ch. 20
fuel cell
A ______ is a voltaic cell in which the reactants are being continuously supplied and the products are being continuously moved (they are efficient and have very low emissions)
protects metals from corrosion
A major benefit of electroplating is that is...
anode
Where does oxidation take place in the electrochemical cell?
Cu, positive ion
Which atom forms an ion that would always migrate toward the cathode in an electrolytic cell
zinc dry cell
Which type of voltaic cell uses a carbon rod as the cathode?
electrode
a conductor used to establish electrical contact with a nonmetallic part of a circuit, such as an electrolyte
electrode potential
a measure between the energy required to move a certain electric charge between the electrodes
half-cell
a single electrode immersed in a solution of its ions
electrolyte (if porous barrier or salt bridge is an option, it would be the best option)
An electrochemical cell consists of two electrodes separated by a(n).....
Negative ions move through the salt bridge from the iron half cell to the chromium half cell
An electrochemical cell is constructed using the reaction of chromium and iron (II) ion, as follows. 2Cr +3Fe 2+ -> 2Cr3+ + 3Fe Which statement best describes this system?
electroplating
An electrolytic process in which solid metal is deposited on a surface is called
The cathode is the object getting plated, the anode is the object doing the plating.
Distinguish between the nature of the anode and the cathode in the process of electroplating...
the substance that is oxidized to the substance that is reduced
During a redox reaction, electrons are transferred from...?
both
Electrolytic or voltaic: The cell contains both a cathode and an anode.
voltaic
Electrolytic or voltaic: The cell reaction converts chemical energy into electrical energy.
electrolytic
Electrolytic or voltaic: The cell reaction converts electrical energy into chemical energy.
both
Electrolytic or voltaic: The cell reaction involves oxidation and reduction.
electrolytic
Electrolytic or voltaic: The cell reaction is endothermic.
voltaic
Electrolytic or voltaic: The cell reaction proceeds spontaneously.
from anode to cathode
Electrons in a galvonic cell normally flow?
Electrolytic cell reactions
Electroplating is an application of...
reactants in a spontaneous energy-releasing redox run are in direct contact
Energy will be released in the form of heat when...?
voltaic cells convert chemical energy to electrical energy. The redox reactions are also spontaneous. Electrolytic cells convert electrical energy to chemical energy. Their redox runs are not spontaneous.
Explain the main differences between a voltaic cell and an electrolytic cell...
connected by a wire and a porous barrier
For an electric current to exist in an electrochemical cell, the two half-cells must be...
cell phone battery, batteries in a flashlight
Give an example of a voltaic cell...
rechargeable battery
Give an example of an electrolytic cell...
Plug it in, input of electricity reverses changing into chemical energy. (the rxn is reversing)
How does a rechargeable cell work?
heat energy can also be transferred
If substances are in direct physical contact...?
most of the energy is released as heat
If the reactants in an electrochemical cell are in contact,
electrical energy INSTEAD of heat
If the substances are separated so they are not in physical contact, the electrons transfer....?
anode
In an electrochemical cell, electrons are generated at the...
electrode at which matter gains electrons
In an electrochemical cell, the cathode is the...(what is happening to the electrons?)
fuel cell
In which type of voltaic cell are the reactants continuously supplied?
1. zinc-carbon dry cells 2. alkaline batteries 3. mercury batteries
Name the three types of dry cells
electrical energy
Oxidation reduction reactions DO NOT occur spontaneously; are driven by _____
1. changes 2. electricity 3. heat
Redox rxns involve __1__ in energy. because these rxns involve e- transfer, the energy can exist as __2__ instead of __3__
+0.76
That Standard electrode potential for Zn is -0.76V. What is the EO for the Zn oxidation half-reaction?
anode
The half reactions with the lower standard reduction potential is the ____
decreases
The oxidation number of the substance taking part in the reaction that occurs at the cathode...
ion movement
The transfer of charge through the electrolyte solution occurs by means of...
false
True or False of the process of electrolysis: Electric energy is generated.
true
True or False of the process of electrolysis: Hydrogen gas is formed at the cathode.
true
True or False of the process of electrolysis: Oxygen gas is formed at the anode.
false
True or False of the process of electrolysis: The process is spontaneous.
Electroplating is an electrolytic process in which a metals ions are reduced and a solid metal is deposited. There must be an input of electrical energy.
What is electroplating?
Zn(s) | Zn 2+ || Cu 2+ | Cu
What is the cell notation for the following net reaction? Zn + Cu 2+ --> Zn 2+ + Cu
Mg -> Mg 2+ + 2e-
What is the half cell notation for the anode? Mg| Mg 2+ || Cu 2+ | Cu
a porous barrier
What is used to keep two half-cells apart but allow charges to flow?
electrical energy is converted into chemical energy
When a car battery is charging, ....
electrons will flow from the hydrogen electrode to the copper electrode
When a copper half-cell is coupled with a standard hydrogen electrode...
1. electrolytic cell 2. electrical energy 3. chemical 4. voltaic 5. chemical energy 6. electrical energy
When a rechargeable camera battery is being recharged, the cell acts as a(n) ___1___and converts___2___ into ___3___ When the battery is being used to power the camera, it acts as a(n) ___4___ and converts ___5___ into ___6___
electroplating
an electrolytic process in which a metal ion is reduced and a solid metal is deposited on a surface
cathode
cations in solution are reduced when they gain electrons at the surface of the _____ to become metal atoms
electrolytic cell
cell in which electrical energy is required to produce a redox reaction and bring about a chemical change in an electrochemical cell
voltaic cell
converts chemical energy to electrical energy
electrolytic cell
converts electrical energy to chemical energy
An anode is where oxidation takes place, a cathode is where reduction takes place.
distinguish between an anode and a cathode in an electrochemical cell ...
voltaic cells
dry cells are _____?
circuit
electric current moves in a closed loop path called a...
ions
electrons moving through the wire balance out the ___ moving through the barrier
directly
individual electrode potential cannot be measured
porous barrier (keeps metal atoms from one half rxn from mixing with the ions from the other half reaction
separates the oxidation and reduction half reaction
reduction potential
tendency for the half-reaction of an electrode to occur as a reduction half-reaction in an electrochemical cell
electrochemistry
the branch of chemistry that deals with electricity-related applications of oxidation-reduction reactions
batteries
the common use of voltaic cells are for ____?
electrode potential
the difference in potential between an electrode and its solution
salt bridge/porous barrier
the double line represent the...?
anode
the electrode where oxidation occurs
cathode
the electrode where reduction occurs
standard electrode potential
the potential of a half-cell under standard conditions measured relative to the standard hydrogen electrode
electrolysis
the process of passing a current through a cell for which the cell potential is negative and causing an oxidation-reduction reaction to occur
voltaic cell
uses spontaneous oxidation-reduction reactions to convert chemical energy into electrical energy
galvanic cells
voltaic cells are also called _____?
electrolytic cell
when a rechargeable battery is charged it is an ____
voltaic cell
when a rechargeable cells changes chemical energy to electrical energy
1. positive 2. favored 3. oxidizing
when electrode potential (Eo) is __1__, that means that H is more likely to give up its e- than the other electrode. positive values are __2__. Ones with positive values are effective __3__ agents
1. negative
when electrode potential is __1__, that means that the other metal is more likely to give up e- than the H electrode