Module 3 Lecture 1

Question 1

How does a reaction with two neutral atoms as reactants produce an ionic compound as a product?

Answer 1

By having half equations within them that the neutral atoms react to cations or anions

Question 2

What happens in redox equations?

Answer 2

The transfer of electrons

Question 3

What must be added to half equations to balance the charge on each side?

Answer 3

electrons

Question 4

What is oxidation?

Answer 4

A process in which chemical species loses and electron (or electrons)

Question 5

What is reduction?

Answer 5

A process in which a chemical species gains an electron or electrons

Question 6

What do we get when we add the two half equations together and balance it?

Answer 6

The overall reduction-oxidation (redox) equation

Question 7

What needs to be cancelled out in the overall redox equation?

Answer 7

electrons and other species that are the same on both sides.

Question 8

What is an oxidant (oxidising agent)?

Answer 8

A chemical substance which gains an electron/s in an electron transfer reaction.
It oxidises the other thing.
Is itself reduced.

Question 9

What is a reductant (reducing agent)?

Answer 9

A chemical substance which loses an electron/s in an electron transfer reaction.
It reduces the other thing.
Is itself oxidised.

Question 10

What is the oxidation number of atoms that exist as elements?

Answer 10

Zero

Question 11

What is the oxidation number of a monotomic (one atom) ion?

Answer 11

The same as the charge on the ion.

Question 12

What is the oxidation number of Hydrogen?

Answer 12

In compounds is +1

Except in metal hydrides which we don’t study.

Question 13

What is the oxidation number of oxygen?

Answer 13

In compounds is -2

Except in Hydrogen peroxide (H2O2) where is is -1

Question 14

What is the sum of the oxidation numbers of atoms in a molecule?

Answer 14

Zero

Question 15

What is the sum of oxidation numbers of atoms in a polyatomic (ions containing more than one atom) ion?

Answer 15

Equal to the charge on the ion

Question 16

If an element undergoes an increase in oxidation number what is happening to it?

Answer 16

It is being oxidised

Question 17

If an element undergoes a decrease in oxidation number, what is happening to it?

Answer 17

It is being reduced.

Question 18

If oxygen is O2 in a neutral molecule what does its oxidation number end up being?

Answer 18

-2 x 2 = -4

Question 19

When balancing the overall equation, what is added to balance oxygen?

Answer 19

H2O

Question 20

When balancing the overall equation, what is added to balance the hydrogens?

Answer 20

H+

Question 21

If an elements oxidation number goes from +7 to +2 how many electrons must be added?

Answer 21

5

Question 22

What must be initially done if the redox reaction is taking place in a basic conditions?

Answer 22

It must first be treated as though it is in acidic conditions, balanced.

Question 23

What must be added with the H+ ions?

Answer 23

OH- ions must be added in the same amount there is H+ ions and to BOTH sides of the equation.

Question 24

What must happen to the side of the equation that has H+ and OH- in it?

Answer 24

They add to give water, so change to H2O

Question 25

What is the last step of balancing redox equations in basic conditions?

Answer 25

Cancel out the extra H20

Question 26

What body system involves a series of redox reactions?

Answer 26

Metabolism