Class Six Flashcards
what is a redox reaction
a reaction in which the oxidation numbers of any of the reactants change
when an atom loses electrons, it undergoes..
oxidation (oxidation # increases)
when an atom gains electrons, it undergoes..
reduction (oxidation # decreases)
LEO the lion says GER
lose electrons = oxidation
gain electrons = reduction
what is a reducing agent
an atom that is oxidized in a reaction (loses electrons)
what is a oxidizing agent
an atom that gains electrons
what happens to the anode
it gets oxidized and its electrons travel to the cathode
where does reduction take place in a galvanic cell
at the cathode
if the cell voltage is positive, the reaction is..
spontaneous
if the cell voltage is negative, the reaction is..
non spontaneous
the more negative the reduction potential..
the weaker the reactant is as an oxidizing agent
the stronger the product is as a reducing agent
the more positive the reduction potential..
the stronger the reactant is as an oxidizing agent
the weaker the product is as a reducing agent
Nernst equation
free energy change equation for a redox reaction
delta G = - (n)FE
value of faraday
96,500 C
what is a concentration cell
galvanic cell with identical electrodes but different ion concentrations
what is an electrolytic cell
it uses an external voltage source to create an electric current that forces a non spontaneous redox reaction to occur
how do electrons move in galvanic cell
from the anode to cathode
Faraday’s law of electrolysis
the amount fo chemical change is proportional to the amount of electricity that flows through a cell
time based cell calculation formula
I = nF/t
main difference between galvanic and electrolytic cells
electrolytic cells have an external power source (galvanic is spon)
where does plating occur
at the cathode
in a galvanic cell, the cathode is..
positive
in an electrolytic cells the cathode is..
negative
where does pitting occur
at the anode
in a galvanic cell, the anode is..
negative
in an electrolytic cell, the anode is..
positive
what happens in alpha decay
alpha particle is emitted out of the parent (2 pro & 2 neu)
parents atomic number goes down by 2 and mass number goes down by 4
beta - decay
when there are too many neutrons in the nucleus
converts neutron → proton which is ejected
atomic number is now 1 greater
beta + decay
when there aren’t enough neutrons → converts proton into a neutron and a positron
atomic number is now 1 less
electron capture
takes an electron from closest shell and uses it to convert proton → neutron
atomic number is reduced by 1
gamma decay
relaxing from an excited state releases a gamma photon
does not change the identity of the nucleus
just an expulsion of energy
what is the mass defect
mass of combined nucleus is less than the sum of the masses of all its individual nucleons
positive mass defect
seen in stable nucleus
Einstein’s equation for mass energy equivalence
E = (delta m)c2
