3: Oxidation Numbers

Question 1

What is oxidation?

Answer 1

Loses electrons or increase in oxidation number

Question 2

What is reduction?

Answer 2

Gains electrons or decrease in oxidation number

Question 3

What is the oxidation number of uncombined elements and explain?

Answer 3

0

Haven’t accepted or donated any electrons

Question 4

What is the oxidation number of a monotomic ion?

Answer 4

Same as it’s charge

Question 5

What is the oxidation number of a molecular ion?

Answer 5

Sum of the oxidation numbers of each atom equals the overall charge

Question 6

What is the oxidation number of a neutral compound?

Answer 6

Sum of the oxidation numbers is 0

Question 7

What is the oxidation number of hydrogen?

Answer 7

+1

Except in metal hydrides when its -1, and 0 in H2

Question 8

What is the oxidation number of oxygen?

Answer 8

-2

Except in peroxides when its -1, and 0 in O2

Question 9

Where will the electrons be in the ionic half equation for reduction?

Answer 9

Reactant + Electrons -> Product

Question 10

Where will the electrons be in the ionic half equation for oxidation?

Answer 10

Reactant -> Product + Electrons

Question 11

What is the oxidation number of fluorine?

Answer 11

-1

Question 12

In general what are the oxidation numbers of metals?

Answer 12

Positive

Question 13

In general what are the oxidation numbers of non-metals?

Answer 13

Negative

Question 14

What do roman numerals show in a compound?

Answer 14

Oxidation number of that ion

Question 15

What does the suffix -ate suggest?

Answer 15

The compound contains oxygen

Question 16

What charge should you assume is on a compound if one is not given?

Answer 16

0

Question 17

What charge is a cation and anion?

Answer 17

Cation - positively charged

Anion - Negatively charged

Question 18

What does redox mean?

Answer 18

Reduction and oxidation is occurring simultaneously

Question 19

What is an oxidising agent?

Answer 19

Something that gets reduced and causes something to get oxidised

Question 20

What is a reducing agent?

Answer 20

Something that gets oxidised and causes something to get reduced

Question 21

What occurs to the oxidation number when one electron is lost?

Answer 21

Increases by 1

Question 22

What occurs to the oxidation number when one electron is gained?

Answer 22

Decreases by 1

Question 23

What do metals normally undergo in a redox reaction?

Answer 23

Donate electrons to form positive ions (positive oxidation numbers)

Question 24

What do non-metals normally undergo in a redox reaction?

Answer 24

Gain electrons to form negative ions (negative oxidation numbers)

Question 25

What is a disproportionation reaction?

Answer 25

Redox reaction where an element from a single species is simultaneously oxidised and reduced

Question 26

When combining half equations what must you ensure with the number of electrons?

Answer 26

Same number must be on each side so they can cancel out

Question 27

What can you add to balance redox reactions?

Answer 27

Electrons H+ ions Water