Redox reactions

Question 1

What is oxidation?

Answer 1

Loss of electrons

Question 2

What is reduction?

Answer 2

The gain of electrons

Question 3

How do you know which element in a compound will have a positive oxidation state?

Answer 3

It will be the least electronegative one

Question 4

What is the oxidation state of an element?

Answer 4

It is always zero

Question 5

What is the oxidation state of a monotonic ion?

Answer 5

It is equal to the charge of the ion

Question 6

What is the usual oxidation state of Hydrogen?

What are the exceptions?

Answer 6

+1

Except when H is in compounds containing elements which are less electronegative, in which case it is -1

Question 7

What is the sum of oxidation states of atoms in a neutral compound?

Answer 7

Zero

Question 8

What is the sum of oxidation states in a charged compound?

Answer 8

It is equal to the overall charge

Question 9

How do you write a half equation in acidic conditions?

Answer 9

1. Balance elements other than O and H in the equation
2. Balance the O atoms by adding water molecules to the opposite side of the equation
3. Balance the H atoms by adding H+ ions to the opposite side
4. Add up the charges on both sides. Make them equal by adding enough electrons to the more +ve side

Question 10

How do you combine to half equations?

Answer 10

Multiply the amount of electrons as needed for them to be equal in both equations

Question 11

How do you determine whether a reaction is redox?

Answer 11

Find out the oxidation state of every species in the equation and see if both reduction and oxidation have occurred?