Physical Chemistry

Question 1

Equilibrium

Answer 1

When the composition of the reactants and products remain constant and the rate of the forward reaction equals that of the reverse reaction.

Question 2

What is the equilibrium constant and what is its unit

Answer 2

K it doesn’t have units

Question 3

What happens when temperate is increased

Answer 3

The equilibrium will shift towards the products If the reaction is endothermic thus increasing the K value

Question 4

What happens when temperature is decreased

Answer 4

When temperature is decreased in an endothermic reaction the equilibrium shifts towards the reactants this causing the k value to lower

Question 5

What effect does a catalyst have on the equilibrium constant

Answer 5

No effect.

Question 6

The ionisation of water equation

Answer 6

H2O(l) + H2O(l) -> H30+(aq) + OH-(aq)

Question 7

What is the H3O+ ion called

Answer 7

The hydronium ion, a hydrated proton

Question 8

What does amphoteric mean and why is this quality applied to water

Answer 8

Amphoteric means can act as an acid or a base

Question 9

What represents the disassociation constant of water

Answer 9

Kw=[H3O+][OH-]

Question 10

How can pH be calculated

Answer 10

pH= -log10[H3O+]

Question 11

Brønsted Lowry definition of an acid

Answer 11

A proton donor

Question 12

Brønsted Lowry definition of a base

Answer 12

A proton acceptor

Question 13

Why acids and bases are completed disassociated in solution

Answer 13

Strong acids and strong bases

Question 14

Which acids and bases are only partially disassociated in solution

Answer 14

Weak acids and weak bases

Question 15

Examples of strong acids

Answer 15

Hydrochloride acid, sulfuric acid, nitric acid.

Question 16

Examples of weak acids

Answer 16

Carbonic acid, sulfurous acid, ethanoic acid.

Question 17

What are strong bases

Answer 17

Solutions of metal hydroxides

Question 18

Examples of weak bases

Answer 18

Ammonia and amines

Question 19

How to calculate the pH of acids

Answer 19

pKa=-log10Ka

Question 20

How to Calculate pH of weak acid

Answer 20

pH= 1/2pKa-1/2log10C

Question 21

What does a strong acid and strong base produce

Answer 21

A neutral salt

Question 22

What does a weak acid and a strong base produce

Answer 22

Alkaline salt

Question 23

What does a strong acid and a weak base produced

Answer 23

Acidic salt

Question 24

Buffer solution

Answer 24

A solution in which the pH remains approximately constant when small amounts of acid and base or water are added.

Question 25

How is an acidic buffer made

Answer 25

A weak acid And it’s salt

Question 26

How do acidic buffers work

Answer 26

The weak acid provides hydrogen ions when these are removed by the addition of a small amount of base. The salt of the weak acid provides the conjugate base which can absorb excess hydrogen ions produced on the addition of a small amount of ache

Question 27

How is a basic buffer made

Answer 27

A weak base and its salt

Question 28

How do basic buffers work

Answer 28

The weak base removes excess hydrogen ions when acid is added and the conjugate acid provides by the salt supplies hydrogen ions when bases are added.

Question 29

How is pH of a buffer be calculated

Answer 29

pH= pKa-log10[acid]/[salt]

Question 30

What is an indicator

Answer 30

A weak acid in which the disassociation constant can be represented as HIn(aq) + H2O(l) -> H3O+(aq) + In-(aq)

Question 31

How is the color of an indicator determined

Answer 31

By the ratio of HIn to In-

Question 32

When does the color change occur in an indicator

Answer 32

When H3O+=KIn

Question 33

Enthalpy of formation

Answer 33

The enthrall change when one mole of a substance is formed from its elements in their standard state

Question 34

Standard state

Answer 34

Pressure of 1 atmosphere and temperature of 298 Kelvin

Question 35

Entropy

Answer 35

The measure of the degree of disorder in a system

Question 36

What type of entropy do solids have

Answer 36

Low entropy

Question 37

What type of entropy do gases have

Answer 37

High degree of entropy

Question 38

What happens to entropy when temperature increases

Answer 38

Entropy increases

Question 39

1st law of thermodynamics

Answer 39

Energy cannot be created nor destroyed so the entropy of the universe is constant

Question 40

2nd law of thermodynamics

Answer 40

States that the total entropy of a reaction system and its surroundings always increases for a spontaneous process

Question 41

What happens to entropy when heat energy is released into surroundings

Answer 41

The entropy of the surroundings increase

Question 42

What happens when heat energy is released from surrounding

Answer 42

The entropy of surroundings decrease

Question 43

Third law of thermodynamics

Answer 43

The entropy of a perfect crystal at 0K is zero

Question 44

What happens when the free energy between reactants and products is negative

Answer 44

The reaction is said to be feasible

Question 45

What happens when the free energy difference between reactants and products are positive

Answer 45

the reaction is not feasible

Question 46

What does free energy equal at equilibrium

Answer 46

^G=0