electrochemistry

what is oxidation?

losing electrons

what is reduction?

gaining electrons

what is an acronym to help remember this?

LEO says GER (losing electrons is oxidation; gaining elections is reduction)

what are other terms that are not in use in modern chemistry?

electronation (reduction)

de-electronation (oxidation)

how do you identify redox (reduction-oxidation reactions)?

assign oxidation states and identify if anything has a change in oxidation state

what is an oxidation state?

the apparent charge of an element; only a tool however

reduction and oxidation happen _____?

simultaneously! (when one compound is reduced, another MUST be oxidized and vice versa)

rule #1 for assigning oxidation states

is it a pure element? if so, it’s oxidation state is 0

rule #2 for assigning oxidation states

is it a simple ion? if so, it’s oxidation state is its charge

what is a simple ion?

an element with a charge (e.g. O²⁺)

rule #3 for assigning oxidation states

is it a compound and does it have hydrogen? if so, hydrogen’s oxidation state is +1

what is the exception to rule #3

if the compound is a hydride (where H is an anion, e.g. LiH), then hydrogen’s oxidation state is -1

rule #4 for assigning oxidation states

is it a compound and does it have oxygen? if so, oxygen’s oxidation state is -2

what is the exception to rule #4

if the compound is a peroxide (e.g. H₂O₂), then oxygen’s oxidation state is -1

rule #5 for assigning oxidation states

the sum of all the individual oxidation states in a species is equal to its overall charge

rule #6 for assigning oxidation states

fluorine and halogens all have an oxidation state of -1

what is the exception to rule #6

if a halogen is bonded to fluorine, it’s oxidation state is not -1 and you must calculate it

what is an oxidizing agent?

a chemical substance that causes oxidation to happen in another substance by accepting electrons (so if something is reduced, it is an oxidizing agent)

what is a reducing agent?

a chemical substance that causes reduction to happen in another substance by losing electrons (so if something is oxidized, it is a reducing agent)

oxidizing and reducing agents can only be _____?

reactants! NOT products

for all redox reactions, what is true?

electrons lost = electrons gained