oxidation and reduction in chemical reactions Flashcards
oxidation
when atoms lose electrons and oxidation number goes up, substances being oxidized are reactants
reduction
atoms gain electrons and oxidation number goes down, substance being reduced is also a reactant
redox reactions
both have oxidation and reduction happening simultaneously (at the same time) and are SINGLE replacement reactions
metal hydride
metal + hydrogen, but hydrogens oxidation is -1
half reactions
show half of a redox reaction, they show either the oxidation or reduction part of a redox reaction, when writing a half reaction you musts show the number of electrons gained or lost
oxidation half reaction
shows an atom or ion losing electrons (show electrons on the product side)
reduction half reaction
an atom or ion gaining electrons (show electrons on the reactant side)
OIL RIG
oxidation is loss
reduction is gained
TABLE J
metals that are more active are more oxidizable = spontaneous, those at the bottom are less oxidizable
what does a wire do?
move electrons from one half cell to another and moves from a anode to cathode
what does the salt bridge do?
the flow of ions between solutions in each half cell and enables redox reactions
anode
oxidation happens, anode is negative in a voltaic cell, and oxidation causes the anode to get smaller (lose mass)
cathode
reduction happens, cathode is positive in a voltaic cell, electrons gained = larger cathode
where do oxidation and reduction reactions take place?
inside electrochemical cells
what are the 2 type of electrochemical cells?
voltaic cell and electrolytic cell
inside the voltaic cell..
redox reactions are spontaneous (by itself) and chemical reactions are needed to PRODUCE electricity EX a battery
inside the electrolytic cell
redox reactions are non spontanneous and electricity is needed to START these chemical REACTIONS
EX: electrolysis or electroplating
parts of a voltaic cell
2 half cells and electrodes
electrodes
metal strips in each half cell
2 half cells
containers that allow for oxidation and reduction half reactions happen
cathode
reduction, cathode is positive in a voltaic cell
voltaic cell diagram
show half reactions
how do you figure out which metal is the anode and which is cathode in a diagram?
TABLE J, metal higher = anode because its oxidized
metal lower = cathode
what is the flow of electrons?
anode to cathode
parts of an electrolytic cell
1 medium, electrodes, wire, battery, and solution
electrodes
anode is POSITIVE in an electrolytic cell, and a cathode is NEGATIVE
battery
there needs to be electricity to force electrons to flow from anode to cathode to force a non spontaneous reaction
electrolysis
electricity used to form a chemical reeaction
solution
positive ion in solution = attracted to cathode (negative)
negative ion in solution = attracted to anode (positive)
electroplating
example of electrolytic cell where electrolysis is used to electroplate (cover something with a different metal) onto a surface
what is the object that gets plated?
a cathode (a metal) is ALWAYS CATHODE and turns (-)
what is the anode made of?
whatever metal is being used for plating
electroplating anode
turns (+)
