3.1.7 ox,red+ redox eq (just things didnt know )

Question 1

oxidation

Answer 1

process of electron loss , increase in oxygen number , gain of oxygen

Question 2

reduction

Answer 2

process of electron gain , decrease in oxidation number, loss of oxygen

Question 3

oxidising agent

Answer 3

one that accepts the electrons. it causes oxidation and gets reduced

Question 4

reducing agent

Answer 4

one that donates the electrons . it causes the reduction and gets oxidised

Question 5

oxidation number rules : group 1&2

Answer 5

group 1 = always +1
group 2 = always +2

Question 6

oxidation number rules : aluminium , fluorine and chlorine

Answer 6

aluminium = always +3
fluorine = always -1
chlorine = -1 unless in compounds with F and O where it becomes positive

Question 7

oxidation number rules : hydrogen, oxygen

Answer 7

hydrogen = +1 unless in metal hydrides where it’s is -1
oxygen = +2 unless in peroxide where it is -1 and if OF2 it is +2

Question 8

half equations

Answer 8

show the transfer of electrons in a redox reaction

for the element oxidised :
_ -> _^+ + e-

for the element reduced :
_^- + e^- -> _

Question 9

half equations for
CuO + Mg -> MgO + Cu

Answer 9

1. Cu^2+ + 2e- -> Cu (reduced)
2. Mg -> Mg^2+ + 2e- (oxidised)

Question 10

balancing redox equations

Answer 10

1) write half equations for the reaction
2) make sure atoms are balanced
3) balance charges by adding electrons
4) multiply equations so number of electrons is the same in both reactions
5) combine both half equations
6) cancel out the electrons as they are the same on both sides

Question 11

look at example slide 11

Question 12

balancing redox equations in aqueous solutions

Answer 12

1) write half equations for oxidation and reduction
2) balance atoms apart from O and H
3) balance O by adding H20 molecules on other side of the equation
4) balance H by adding H+ ions on the other side of the equation
5) balance the charges on both half equations by adding electrons
6) make both half equations have the same number of electrons by multiplying whole equations
7) combine the equations together
8) cancel out the electrons (as they are equal)
9) cancel out things that are the same on both sides

Question 13

look at example slide 13

Question 14

half equations from balanced equation

Answer 14

1) put oxidation numbers above every element
2) increase in oxidation number = oxidised
3) decrease in oxidation number = reduced
4) write out equation for element oxidised from original equation
5) add electrons to equation
6) write out equation for the element reduced from original equation
7) add electrons to equation
8) if atoms don’t balance , add H+ ions or H20 molecules if in equation