chem strat
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- What should you note about a galvanic cell?
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(1) the cell potential must be greater than zero.
(2) cell potential is equal to the cathode potentail minus the anode potential when they are written as reductions.
(3) reduction - the gain of electrons - occurs at the cathode.
(4) oxidation - the loss of electrons - occurs at the anode. - For galvanic cell, the electrode with the highest reduction potential will be the (cathode/anode)?
- cathode.
- When an electrochemical cell operates spontaneously, it is called a _______.
- galvanic cell.
- For voltaic cell, if the cell potential is positive, G is (less/greater) than zero.
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- Less than zero, by the relationship G=-nFE;
- and therefore spontaneous - In a voltaic cell, the electrons always flow from the (anode/cathode) to the (anode/cathode).
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- anode to cathode.
- electrons are loss at the anode; and gained at the cathode. - For a voltaic cell, what happens when the flow of electrons stop?
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(1) the cell potential is zero.
(2) the system is at equilibrium (recall the reationship G=-nFE). - (T/F) For a voltaic cell at equilibrium, the concentration of no reactant or product goes to zero.
- True.
- (T/F) Electrochemical reactions are spontaneous.
- False; they are not spontaneous. They can be driven to completion by passing an electric current through the solution (process is called electrolysis and the cell is called an electrolytic cell).
- How is an electrolytic cell different from a galvanic cell?
- In an electrolytic cell, the anode is positively charged and the cathode is positively charged; which is opposite to that of the galvanic cell.
- (T/F) Reduction occurs at the cathode; and oxidation occurs at the anode for both the galvanic and electrolytic cell.
- TRUE.
- What is positively and negatively charged in the electrolytic cell?
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cathode = negatiuve
anode = positive - What is positively and negatively charged in the galvanic cell?
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cathode = positive
anode = negative - What is the faraday constant?
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- magnitude of the charge of one mole of electrons.
- used in equation G=-nFE and Nernst equation. - What are exsamples of strong electrolytes?
- NaCl, KCl, HCl, HBr, and HI.
- What are example of weak electrolytes?
- water, HF< acetic acid, benzoic acid, and ammonia.
- What is an electrolyte?
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a substance that ionizes to yield an electrically conducting solution;
- a strong electrolyte is one that ionizes completely or nearly completely, and a weak electrolyte doesn't ionize very much at all. - What is the reationship between charge, amperes and time?
- Charge is equal to current in Amps times time in seconds.
- Is pure water an electrolyte?
- No; it will not conduct electricity.
- What charge does a carbonate ion have?
- -2 charge;
- If something is precipitated, what should you think if you see a bunch of reactions?
- look for the solid!
- (T/F) The hydroxides of all Group I and II metals are strong bases.
- True;
- What are the most common strong acids?
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sulfuric acid (H2SO4),
nitric acid (HNO3),
hydroclhloric acid (HCl),
Hydrobromic acid (HBr),
Hydroiodic acid (HI),
Chloric Acid (HClO3),
perchloric acid (HClO4)