oxidation and reduction

Question 1

what is oxidation

Answer 1

loss of electrons
oxidation state increases

Question 2

what is reduction

Answer 2

gain of electrons
oxidation state decreases

Question 3

eg of redox reaction - formation of magnesium chloride

Answer 3

Mg(s) +Cl2(g) -> Mg2+ + 2Cl- (s)

mg -> mg2+ + 2e- oxidation
cl2 +2e- -> 2cl- reduction

Question 4

what is a reducing agent

Answer 4

electron donor
a reducing agent is itself oxidised

Question 5

what is an oxidising agent

Answer 5

electron acceptor
and oxidising agent is itself reduced

Question 6

rules for finding oxidation states

Answer 6

-uncombined elements - mg , na , cl2 have an oxidation state of 0
-sum of all oxidation states in a compound - nacl - is 0
-oxidation of a simple ion - mg2+- is equal to its charge
-sum of all oxidation states in a complex ion - nh4+ - is equal to its charge

Question 7

assigned oxidation states

Answer 7

UNDER-uncombined elements (0)
MY-metals
FACE-flourine(-1)
HERES-hydrogen(+1)
OUR-oxygen(-2)
CHIN-chlorine-(-1)

Question 8

if a substance is oxidised

Answer 8

oxidation state increases

Question 9

if a substance is reduced

Answer 9

oxidation state decreases

Question 10

roman numerals in oxidation states

Answer 10

oxidation state is equal to the roman numeral

Question 11

rules for balancing half equations

Answer 11

balance the main atom (not H OR O) first
balance O using H2O
balance H using H+
balance charge using electrons

Question 12

steps for combining half equations

Answer 12

multiply 1 or both half equations until they both have the same number of electrons
add the reactants from both equations together
add the products from both equations together
cancel out electrons

Question 13

disproportionation reactions

Answer 13

an element is both oxidised and reduced