O.2

Question 1

The sun radiates energy from which regions of EM waves?

Answer 1

Infrared, visible and ultraviolet.

Question 2

The earth mainly radiates energy from which region of EM waves?

Answer 2

Infrared.

Question 3

Carbon dioxide and methane in the atmosphere are examples of what?

Answer 3

Greenhouse gases.

Question 4

What are two things that can happen when carbon dioxide and methane absorb the infrared radiation from the earth to cause warming of the atmosphere?

Answer 4

1. Absorption of infrared causing an increase of vibrational energy of carbon dioxide and methane molecule, and this energy can be transferred to other molecules in the air, increasing their kinetic energy, and raising the temperature of the air.
2. Some infrared is re-emitted by molecules, back towards earth as well as out towards space.

Question 5

Apart from carbon dioxide and methane, what other naturally abundant gas in the atmosphere is a greenhouse gas?

Answer 5

Water vapor.

Question 6

What is the IR window?

Answer 6

The certain wavelengths of infrared radiation that water vapor doesn’t absorb.

Question 7

What is the general definition of an acid?

Answer 7

A substance which donates H+ ions in a chemical reaction.

Question 8

What is the general definition of a base?

Answer 8

A substance which accepts the H+ ions in a chemical reaction.

Question 9

What is a reaction known as when it involves the transfer of H+ ions from one substance to another?

Answer 9

An acid-base reaction.

Question 10

A proton donor refers to what kind of substance?

Answer 10

An acid.

Question 11

A proton acceptor refers to what kind of substance?

Answer 11

A base.

Question 12

What is it called when a base is dissolved in a solution?

Answer 12

Alkali.

Question 13

What is pH a measure of?

Answer 13

The concentration of H+ ions in a solution.

Question 14

What mathematical equation is pH defined as?

Answer 14

-log10([H+])

Question 15

Solutions with a pH of what value is considered neutral?

Answer 15

7

Question 16

When pH value changes by 1, what factor does the concentration of H+ ions change by?

Answer 16

Factor of 10.

Question 17

What pH values are defined for acids?

Answer 17

Less than 7.

Question 18

What pH values are defined for alkalis?

Answer 18

More than 7.

Question 19

What is the definition of a strong acid?

Answer 19

It has a strong tendency to donate H+ ions and therefore dissociates completely in solution.

Question 20

With HA representing a strong acid, what is the equation of the reaction where HA dissociates completely in solution?

Answer 20

HA(aq) + H2O(l) → H3O+(aq) + A-(aq), if water is in excess and left out it can be simplified to,
HA(aq) → H+(aq) + A-(aq)

Question 21

What are three examples of strong acids?

Answer 21

HCl, HNO3, H2SO4.

Question 22

What is the definition of a weak acid?

Answer 22

It has a weak tendency to donate H+ ions and therefore doesn’t dissociate fully in solution.

Question 23

With HA representing a weak acid, what is the equation of the reaction where HA dissociates partially in solution?

Answer 23

HA(aq) ⇌ H+(aq) + A-(aq), the equilibrium sign shows that a significant concentration of undissociated HA is present alongside H+ and A-.

Question 24

In terms of equilibrium, when the position of the equilibrium is to which side is the defined as a weak acid?

Answer 24

To the left.

Question 25

How can the pH of a strong acid be calculated?

Answer 25

Because HA dissociates fully, [HA] is effectively the same as [H+], then you can calculate using -log10[H+].

Question 26

What is the rearranged pH equation that allows you to calculate the concentration of H+ given the pH?

Answer 26

10^-pH

Question 27

What is Ka?

Answer 27

An equilibrium constant known as acid dissociation constant used to calculate the concentration of H+ ions in a weak acid.

Question 28

What are the two assumptions about weak acids that allows us to find the concentration of H+?

Answer 28

1. [H+] = [A-], so the top can be simplifies to [H+]^2, this is an assumption because there could be another source of H+, such as water but it produces insignificant amounts of H+.
2. [HA]equi = [HA]init, because Ka is small assume it doesn’t dissociate much at all.

Question 29

When does the assumption [H+] = [A-] become less valid?

Answer 29

At lower concentrations of acid.

Question 30

When does the assumption [HA]equi = [HA]init become less valid?

Answer 30

As Ka increase, so with not so weak acids.

Question 31

What is the definition of a strong alkali?

Answer 31

Dissociates completely in solution.

Question 32

What equilibrium is used to calculate the pH of a strong alkali?

Answer 32

Kw, ionization product of water.

Question 33

What are the ionic products of water?

Answer 33

H+(aq) and OH-(aq).

Question 34

What is the equation that shows the ionization of water?

Answer 34

H2O(l) ⇌ H+(aq) + OH-(aq)

Question 35

What is the expression of Kw?

Answer 35

Kw = [H+(aq)][OH-(aq)]

Question 36

What is the value of Kw?

Answer 36

1x10^-14

Question 37

Using the ionic products of water, what is the definition of an acidic solution?

Answer 37

[H+] > [OH-]

Question 38

Using the ionic products of water, what is the definition of an alkaline solution?

Answer 38

[H+] < [OH-]