redox

what is a redox reaction?

transfer of electron density from one atom to another

when an atom loses electrons, what type of reaction is it? which agent is it?

oxidation reaction
reducing agent

when an atom gain electrons, what type of reaction is it? which agent is it?

reduction reaction
oxidizing agent

can oxidation and reduction occur separately? why not

no because otherwise electrons would appear as a product of the reaction - something must accept the electrons

what is the oxidation number of any element by itself?

zero

what is the oxidation number of any simple monatomic ion (ion by itself)?

equal to it’s charge

ex: S^2- = 2-

when is the oxidation number of oxygen NOT -2

in peroxide (-1)

when is the oxidation number of hydrogen NOT +1

in hydride

what characteristic of elements is the activity series based on?

atomic radius: gets less reactive as you move in on the periodic table

what is a galvanic cell? what are two other names for it?

when the flow of electrons from one chemical reaction to another happens through an outside circuit resulting in current
two names: Daniell cell and voltaic cell

what is current measured in? what does it measure?

Amperes (A) - measure of electrons that flow past a certain point in the circuit at any given moment

When two half-cells are connected, what would the potential difference measured by the voltmeter show?

the difference between the two cells’ electrode potentials

at which electrode does oxidation occur at? what does it supply?(OX AN)

the anode - supplies electrons

at which electrode does reduction occur at? (RED CAT)

the cathode - electrons flow to it

what is the reference electrode when determining half cell potentials?

hydrogen electrode - E = 0V

If the cell potential is very negative, what does that mean about the species?

weak oxidant, strong reductants

what is the equation for determining overall cell potential?

E = E_red - E_ox

what is the formula for predicting cell spontaneity

change in G = -nFE
n = number of electrons transferred
F = 96500 C/mol

Therefore if E is positive than G will be negative so a spontaneous reaction is possible