Reaction Feasibility + Chemical Equillibrium for some reason

Question 1

What is the standard enthalpy of formation?

Answer 1

The enthalpy change when 1 mole of a substance is formed from its elements in their standard states

Question 2

standard enthalpy equation?

Answer 2

ΔH°= ΣΔHf (products) – ΣΔHf (reactants)

Question 3

What is entropy(S)?

Answer 3

A measure of the degree of disorder

Question 4

What does the second law of thermodynamics state?

Answer 4

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

Question 5

Heat energy absorbed by the reaction system from the surroundings

Answer 5

decreases the entropy of the surroundings

Question 6

an increase in temperature increases

Answer 6

entropy

Question 7

What does the third law of thermodynamics state?

Answer 7

The entropy of a perfect crystal at 0K is zero

Question 8

Gibbs equation?

Answer 8

ΔG° = ΔH° - TΔS°

Question 9

negative ΔH°
positive ΔS°

Answer 9

ΔG° is negative, reaction is always feasible

Question 10

positive ΔH°
negative ΔS°

Answer 10

ΔG° is positive, reaction is never feasible

Question 11

negative ΔH°
negative ΔS°

Answer 11

Reaction is only feasible at low temperatures

Question 12

positive ΔH°
positive ΔS°

Answer 12

Reaction is only feasible at high temperatures

Question 13

To calculate the temperature let

Answer 13

ΔG°=0

Question 14

K depends on the reaction

Answer 14

temperature

Question 15

K>1 means

Answer 15

the equillibrium lies to the right (more products than reactants)

Question 16

K<1 means

Answer 16

the equillibrium lies to the left (more reactants than products)

Question 17

K=

Answer 17

[C][D] /[A][B] (products on the numerator, reactants on the denominator) (raise each to the number of moles)

Question 18

What is the equillibrium constant? (K)

Answer 18

characterises the equillibrium composition of the reaction mixture

Question 19

The concentrations of pure liquids and solids is

Answer 19

1

Question 20

For endothermic reactions, a rise in temperature causes an _________ in K and the yield of the product is ____________

Answer 20

increase, increased

Question 21

What does amphoterric mean?

Answer 21

can act as both an acid and a base

Question 22

pH equation?

Answer 22

pH= -log[H+]

Question 23

What is Kw?

Answer 23

dissociation constant

Question 24

Kw equation?

Answer 24

Kw=[H+][OH-]

Question 25

H+ equation?

Answer 25

[H+]=10^-pH

Question 26

How to calculate the concentration of one ion if the other ion is known?

Answer 26

use Kw or pH+pOH=14

Question 27

Bronsted-Lowry definition of an acid?

Answer 27

A proton donor

Question 28

Bronsted-Lowry definition of a base?

Answer 28

a proton acceptor

Question 29

What does Ka represent?

Answer 29

The acid dissociation constant

Question 30

pKa equation? (strong acid pH equation)

Answer 30

pKa=-logKa

Question 31

weak acid pH equation?

Answer 31

pH=1/2pKa-1/2logc

Question 32

A soluble salt of a strong acid + strong base=

Answer 32

neutral solution

Question 33

A soluble salt of a weak acid + strong base=

Answer 33

alkaline solution

Question 34

A soluble salt of a strong acid + weak base=

Answer 34

acidic solution

Question 35

What is a buffer solution?

Answer 35

one in which the pH remains approximately constant when small amounts of acid, base or water are added

Question 36

What is a buffer made up of?

Answer 36

A weak acid/base and the salt of that weak acid/base

Question 37

Describe an acid buffer solution

Answer 37

In an acid buffer solution, 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 when these are produced by the addition of a small amount of acid

Question 38

Describe a basic buffer solution

Answer 38

In a basic buffer solution the weak base removes excess hydrogen ions, and the conjugate acid provided by the salt supplies hydrogen ions when these are removed.

Question 39

pH of acid buffer solution equation

Answer 39

pH=pKa-log x [acid]/[salt]

Question 40

At 25C the value of Kw is

Answer 40

1 x 10^-14