3.1 Physical Chemistry: .7 Oxidation, reduction and redox reactions Flashcards Preview

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Flashcards in 3.1 Physical Chemistry: .7 Oxidation, reduction and redox reactions Deck (22):
1

what is oxidation?

the loss of electrons

2

what is reduction?

the gain of electrons

3

what is an oxidising agent?

atom/molecule that accepts electrons and gets reduced its self

4

what is an reducing agent?

atom/molecule that donates electrons and gets oxidised its self

5

what does the oxidation state of an element tell you?

-it tells you the total number of electrons it has donated or accepted

6

what are the oxidation states of elements?

0

7

what are the oxidation states of elements bonded to identical atoms?

0

8

what are the oxidation state of an overall compound?

the ion charge
e.g if has no charge the oxidation is 0
if it has a charge of -2 then the oxidation state is -2

9

what is the oxidation state of a simple monatomic ion?

it is the same as its charge
e.g Na+ would have oxidation state of +1

10

what is the oxidation state of elements in group 1 in a compound?

+1

11

what is the oxidation state of elements in group 2 in a compound?

+2

12

what is the oxidation state of elements in group 6 in a compound?

-2

13

what is the oxidation state of elements in group in group 7?

-1

14

what is the oxidation state of oxygen,
what are the exceptions?

-the oxidation state of oxygen is -2
-but when oxygen is in a peroxide it is -1 H2O2
-when it is bonded with fluorine it is +2 e.g OF2
-when its in O2F2 it is +1

15

what is the oxidation state of chlorine? what are the exceptions?

-the oxidation state of Chlorine is -1
-BUT when it is bonded with Oxygen it is +1

16

what is the oxidation state of Hydrogen? what are the exceptions?

-the oxidation state of Hydrogen is +1
-BUT when it is bonded with any element in group 1 it is -1

17

what is the oxidation state of Cl in the Chlorate (I) ion (ClO-)

+1
because...
Cl O-
+1 -2= -1

18

what does an increase in oxidation number mean?

-it means that the chemical has gone through oxidation
-there has been a loss of electrons

19

what does a decrease in oxidation number mean?

-it means that the chemical has gone through reduction
-there has been a gain of electrons

20

state whether this reaction is a redox reaction?
Zn + 2HCl --> ZnCl2 + H2

Zn + 2HCl --> ZnCl2 + H2
ox no of Zn= 0
ox no of H=+1
ox no of Cl= -1

ox no of Zn= +2
ox no of Cl= -1
ox no of H= O

Zn has gone up in oxidation number so it is oxidation
Hydrogen has gone down in oxidation number so it reduction.
Therefore this is a redox reaction.

21

in this reaction state which is the oxidant and which is the reducing agent
Zn + 2HCl --> ZnCl2 + H2

H+ is the oxidant (it oxidised the Zn)

Zn is the reducing agent (it reduces the H+ ion)

22

when balancing a combined ionic equation, what are the steps that you should follow?

-work out the oxidation states of each element
- work out the electrons
-work out if there water molecules and H+ ions are required
-balance the electrons