Chem Ch. 20

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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


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