Vocab.
What is an oxidizing agent?
Electron acceptor
Species is reduced
What occurs when electrons are lost
Oxidation
Name the oxidation numbers for SnH4
Sn=+4
H=-1
What occurs at the cathode?
Reduction (RED CAT, AN OX)
What is the anode in a dry Cell?
Zn
oxidation-reduction or redox reactions
What occurs when Electrons are gained?
Reduction
Oxidation numbers for K2SO4
S=+6
O=-2
What is the equation to find Cell Voltage
E° cell=Ered-Eox
How does a battery work?
A battery functions by transferring electrons
through an external wire from the reducing agent
to the oxidizing agent.
What is the purpose of a salt bridge?
balance charges, full of + and - ions to balance
anions move to anode
cations move to cathods
What's an electrode?
an electrical conductor that connects the metallic parts of a circuit to a non-metallic part
Calculate the standard cell potential of a cell consisting of MglMg2+ and PblPb2+.
DOUBLE: Write the half-cell reactions and the overall cell reaction
E=Ered-Eox
-0.13V-(-2.37)=2.29 V
(Mg-->Mg2+ +2e- anode
Pb2++2e- ---> Pb cathode
Pb2+ +Mg--->Pb+Mg2+
Which way do electrons flow in a voltaic cell?
Toward the cathode (more positive)
What makes alkaline different from dry cell?
Alkaline is the same thing, but in a basic enviornment
What is Electrolysis
The process in which electrochemical energy is used to bring about a chemical change
Is the following reaction spontaneous?
Ni+Fe2+--->Ni2+ + Fe
Ni is oxidized and Fe is reduced so Fe-Ni
-0.45V-(-0.26 v0=-0.19 V
VOLTAGE IS NEGATIVE SO NONSPONTANEOUS
Which way does energy move in electrochemical and electrolytic cells?
Chemical-energy out
Electrolytic-energy in
What is the anode and cathode in Lead Storage Batteries
Anode (-) : Lead grids
Cathode (+) : “Spongy” lead in grid
What is the standard Cell Potential?
—a quantitative measure of the tendency of
reactants to proceed to products when all are
in their standard states at 25 ˚C.
Balance the redox equation MnO4- + C2O42---->MnO2+ CO32-
2MnO4- + 3C2O42-+2H2O--->2MnO2+6CO32-+4H+
What is the charge of the anode in electrolytic cells
POSITIVE
When Zn metal is placed in Cu2+ ions, what happens?
What's oxidized and what's reduced?
With time, Cu plates out onto Zn metal strip, and Zn strip “disappears.”
Zn is oxidized and is the reducing agent
Cu2+ is reduced and is the oxidizing agent