Chapter 12: Electrochemistry Flashcards
____________ cells are contained systems in which redox reactions occur.
electrochemical
What are the 3 types of electrochemical cells?
- Galvanic / voltaic cells
- Electrolytic cells
- Concentration cells
All three types of electrochemical cells contain ____________, where redox takes place.
electrodes
The electrode where oxidation occurs is called the ____________
anode
AN OX RED CAT
The electrode where reduction occurs is called the ____________
cathode
AN OX RED CAT
The ____________ ________ corresponds to the voltage or electrical potential differene of the cell.
electromotive force (emf)
If emf is positive, then the cell can do what? What does this mean?
The cell can release energy (∆G < 0); it is spontaneous
If emf is negative, what does a cell have to do? What does this mean?
The cell must absorb energy (∆G > 0), which means it is nonspontaneous
For all electrochemical cells, which direction do electrons move? Which way does the current run?
Electrons move from anode to cathode; current runs from cathode to anode
All nonrechargeable batteries you own are ____________ cells, also called ________ cells.
galvanic; voltaic
Because household batteries are used to supply energy to a flashlight or remote control, the reactions in these galvanic cells must be ____________
spontaneous
Free energy change and electromotive force always have (opposite/same?) signs.
opposite
In a galvanic cell, 2 electrodes of distinct chemical identity are placed in separate compartments, which are called ________-________. They are connected by a ________________ material..
half-cells; conductive
Surrounding each of a galvanic cell’s electrodes is an aqueous ____________ solution composed of cations and anions.
electrolyte
Connecting the two half-cell solutions of a galvanic cell is a ________ ________
salt bridge
When the electrodes are connected to each other by a conductive material, charge will begin to flow - why?
the redox reaction taking place between the 2 half cells
What do we accomplish by separating redox half-reactions into 2 compartments?
You can harness the energy and use it to do work by connecting various electrical devices into the circuit between the 2 electrodes
What would happen if there were no salt brdige?
If there were only a wire, the reaction would stop quickly because an excess positive charge would build up on the anode and excess negative charge on the cathode. It would create a countervoltage.
What does the salt bridge accomplish?
It permits the exchange of cations and anions. It has an inert electrolyte, which contains ions that will not reat with the electrodes or with the ions in solution.
While anions from the salt birdge (Cl-) diffuse into the solution on the anode side (ZnSO4) to balance out the charge of the newly created Zn2+ ions, the cations of the salt bridge (K+) flow into the solution on the cathode side (CuSO4) to balance out the charge of the sulfate ions left in solution when the Cu2+ ions are reduced to Cu and precipitate onto the electrode. This is called ____________ or ________________.
plating, galvanization
