ch8 redox rxns

what are redox reactions

reduction-oxidation. involve the transfer of electrons from one species to another.

at what times do redox reactions occur

they occur at the same time simultaneously

what are half equations used to represent

redox reactions

what is oxidation

defined as the loss of electrons

what is reduction

defined as the gain of electrons

explain the reducing agent

donates the electrons to another substance, causing that substance to be reduced. the reductant itself is oxidised (loses electrons).

explain the oxidising agent

accepts electrons from another substance, causing that substance to be oxidised. the oxidant itself is reduced.

how do you balance half equations

may have to multiply by a factor before adding the half equations together

explain a halogen displacement reaction

occur in which one halogen is oxidised (the halide ions lose electrons to produce the elemental halogen) and the other halogen is reduced to produce halide ions

what is the oxidation number of free elements

0

what is the oxidation number of simple ions in an ionic compound

equal to the charge on the ion

what is the oxidation number of oxygen in a compound

-2

what is the oxidation number of hydrogen in a compound

1

the sum of oxidation numbers of a polyatomic ion is equal to the what?

to the charge of the poly atomic ion

what are exceptions to oxygens with its usual oxidation number

• when combined with fluorine, the oxidation number is a +2 because fluorine is more electronegative

• in peroxides, oxygen has an oxidation number of -1

what indicates that oxidation has occurred

an increase in oxidation number over the product side

what indicates that reduction has occurred

a decrease in oxidation number over the reduction side

what must occur for an oxidation reaction to occur

corresponding reduction reaction

how can you tell if a reaction is a redox or not

if there is no change in oxidation number of all elements in the equation

does the oxidation number of an oxidising agent increase or decrease

decrease

does the oxidation number of a reducing agent increase or decrease

increase

what are the rules to balancing half-equations under acidic conditions

1. balance the oxygen by adding water atoms

2. balance the hydrogen atoms by adding H+ ions

3. balance the charge by adding electrons

4. add states

how do you balance half-equations with electrons

make sure the number of electrons used in reduction is equal to the number of electrons released in oxidation

what are the top 5 strongest oxidising agents

1. Au

2. Ag

3. Cu2+

4. Pg2+

5. Sn2+

what are the top 5 strongest reducing agents

1. Li

2. K

3. Ca

4. Na

5. Mg

on the reactivity series, where do the strong oxidising agents belong

higher than the weak oxidising agents

on the reactivity series, where do the strong reducing agents belong

lower than the strong reducing agents

what do metal displacement reactions involve

the transfer of electrons from a more reactive metal to the positive ions of a less reactive metal in solution