topic 3 - redox 1

Question 1

definition of oxidation numbers

Answer 1

oxidation numbers tells us the number of electrons lost/gained/shared by an element during chemical bonding

Question 2

what is oxidation

Answer 2

oxidation is the loss of electrons
addition of oxygen
and the loss of hydrogen

Question 3

what is reduction

Answer 3

reduction is the gain of electrons
the loss of oxygen
and the addition of hydrogen

Question 4

what is an oxidising agent

Answer 4

-a species that oxidises another species by removing 1 or more electrons from it
-when an oxidising agent reacts it gains electrons so is reduced

Question 5

what is a reducing agent

Answer 5

-a species that reduces another species by adding 1 or more electrons
-when a reducing agent reacts it loses electrons so is oxidised

Question 6

what is the oxidation number of an uncombined element

Answer 6

0

Question 7

what is the sum of the oxidation numbers in a compound

Answer 7

-if the compound is neutral the sum of the oxidation numbers is 0
-if the compound has an overall charge the sum of the oxidation numbers is equal to the charge on the compound

Question 8

in a compound which element is given the negative oxidation number

Answer 8

-oxygen is usually -2
-but always the more electronegative element is given the negative oxidation number

Question 9

what is the oxidation number of flourine in a compound

Answer 9

always -1

Question 10

what is the oxidation number of hydrogen in a compound

Answer 10

+1
except when combined with a less electronegative atom, then it is -1

Question 11

what is the oxidation number of oxygen

Answer 11

-2
except in peroxides, then it is -1
except when combined with flourine, then it is +2

Question 12

if the oxidation number of an element gets more negative, has the element been oxidised or reduced

Answer 12

reduced

Question 13

if the oxidation number of an element gets more positive, has the element been oxidised or reduced

Answer 13

oxidised

Question 14

what is disproportionation

Answer 14

the simultaneous oxidation and reduction of an element in a species in a single reaction

Question 15

what is meant by the systematic name of a compound

Answer 15

in an ion can have different oxidation numbers, the oxidation number of the ion is given to specify which ion is being used
e.g. iron(II) sulfate is FeSO4
iron(III) sulfate is Fe2(SO4)3