Physical y13

Question 1

what is entropy

Answer 1

The tenancy for everything to move from a state of order to chaos. increase in disorder.

Question 2

How do you calculate entropy change

Answer 2

sum of entropy of products- sum of entropy of reactants

Question 3

Units of entropy

Answer 3

J K-1 Mol-1

Question 4

Units of enthalpy

Answer 4

Kj mol-1

Question 5

What does the y-intercept show on a Gibbs free energy change

Answer 5

delta H.
enthalpy change

Question 6

What does the gradient show on a gibbs free energy graph

Answer 6

-delta S
entropy change

Question 7

How do you calculate gibbs free energy change

Answer 7

delta G= delta H- k delta S

Question 8

When will a reaction occur, relevant to gibbs free energy

Answer 8

if G < 0

Question 9

If delta H is positive and delta S is positive what happens to the feasibility as temp increases

Answer 9

Feasible above a certain temperature

Question 10

+ve enthalpy -ve
l
————————————-
entropy l
-ve l
what is G for each quadrant

Answer 10

high temp to always -ve
be -ve

always +ve low temp
to be -ve

Question 11

units of delta G

Answer 11

KJ mol-1

Question 12

What is enthalpy change of atomisation

Answer 12

amount of energy required to produce 1 mol of atoms, normally diatomic gas-> atoms

Question 13

What is enthalpy change of ionisation

Answer 13

The amount of energy required to remove 1 mol of electrons from 1 mol of substance in their gaseous state

Question 14

Oxidation state of H, O, Halogen, Group 1 metals

Answer 14

H- +1 Unless metal hydride (-1)
O- -2 unless h2o2 or with F
Halogen- -1
group 1- +1

Question 15

What is enthalpy change of formation

Answer 15

Amount of energy required to form 1 mol of a compound

Question 16

Lattice formation energy

Answer 16

enthalpy change when 1 mol of a solid ionic compound is formed from its gaseous ions.

Question 17

Enthalpy of lattice dissociation

Answer 17

enthalpy change when i mol of solid ionic compound dissociates to form its constituent gaseous ions.

Question 18

enthalpy change of combustion

Answer 18

Enthalpy change when 1 mol of substance is burned in excess oxygen

Question 19

hydration enthalpy

Answer 19

the enthalpy change when water molecules surround 1 mol of gaseous ions

Question 20

Enthalpy of solution

Answer 20

Enthalpy change when 1 mol of solute completely dissolves in enough solvent that the molecules or ions are far enough apart to not interact with each other.

Question 21

What is enthalpy of the 1st electron affinity

Answer 21

the enthalpy change when 1 mol of gaseous atoms is converted to 1 mol of gaseous 1- ions

Question 22

how are ionic bonds dependant on charge density

Answer 22

small atoms with high charge are charge dense and these can form stronger ionic bonds

Question 23

What can cause a difference in theoretical ionic lattice enthalpies and experimental ones

Answer 23

covalent character

Question 24

How can you calculate enthalpy of solution

Answer 24

enthalpy of lattice dissociation + sum of enthalpies of hydration of ions

Question 25

What is mean bond enthalpy

Answer 25

enthalpy change when 1 mol of gaseous molecules break to form 2 free radicals, averaged over a range of compounds

Question 26

What is a typical rate equation

Answer 26

k [A]^m [B]^n

Question 27

what does k represent in the rate equation

Answer 27

the rate constant

Question 28

what is the power the conc of reactant is raised to known as in the rate equation

Answer 28

the order of the reactant

Question 29

in a multi step reaction, which step is seen to limit the reaction

Answer 29

the rate determining step, which is the slowest step

Question 30

How can we measure changing rates`

Answer 30

change in ion concentration volume of gas produced time taken for visual change pH probe titrations at given intervals.

Question 31

What do rate vs time graphs look like for different orders

Answer 31

zero order, straight horizontal line first order linear line second order quadratic curve

Question 32

What is the arrhenius equation

Answer 32

k=Ae^(-Ea/RT)

Question 33

What is the gas constant

Answer 33

8.31 KJ K-1 mol-1

Question 34

how can you rearrange the arrhenius equation using logarithms

Answer 34

ln(k)= ln(A)- Ea/RT

Question 35

What is the equation for the contact process

Answer 35

2SO2 +02 <=> 2SO3

Question 36

What is partial pressure

Answer 36

the pressure one of the gases in a mixture would exert if it were in a container alone

Question 37

how do you calculate mole fraction

Answer 37

n(partial atom)/ n(total)

Question 38

how do you calculate partial pressure

Answer 38

mole fraction x total pressure

Question 39

What should be used for electrode if both elements of cell are in same state

Answer 39

platinum as it is inert

Question 40

what happens to an oxidising agent

Answer 40

it gets reduced

Question 41

what happens to a reduction agent

Answer 41

it gets oxidised

Question 42

how do oxidation numbers need to be ordered

Answer 42

-2 charge then number

Question 43

What does a large, +ve electrode potential mean in terms of redox agents

Answer 43

strong oxidising agent, weak reduction agent

Question 44

when constructing a cell, which electrode potential equation should be flipped`

Answer 44

most -ve

Question 45

What connects the half cells in a cell

Answer 45

a salt bridge

Question 46

What are electrode potentials compared to

Answer 46

the electrode potential of hydrogen (0)

Question 47

What conditions are the standard H+ electrode measured under

Answer 47

1M H+ 298K] 100kPa Platinum electrode

Question 48

Which way round are electrode potential equations written

Answer 48

always as reductions

Question 49

how do you calculate the electrode potential of a cell

Answer 49

electrode potential RHS- electrode potential LHS RHS- most +ve LHS- most -ve

Question 50

How do you draw a Zn Cu cell short hand

Answer 50

Zn(s) I Zn2+ (aq) II Cu2+ (aq) I Cu ( s) must include state symbols I represents phase boundary II represents salt bridge

Question 51

How does concentration affect electrode potential

Answer 51

more concentrated -> more +ve electrode potential

Question 52

What is a bronstead lowri acid

Answer 52

proton donor

Question 53

what is a bronstead lowri base

Answer 53

proton acceptor

Question 54

equation for pH

Answer 54

pH= -log[H+]

Question 55

how many d.p should pH be to

Answer 55

2

Question 56

What is Kw

Answer 56

1 x 10^-14 mol^2 dm^-6 at 298K and 1 atm

Question 57

equation for kw

Answer 57

[H][OH-]=[H+]^2

Question 58

explain steps for calculating pH when 10cm3 acid added to 25cm3 base

Answer 58

- work out moles H+ and OH- - work out excess OH- -work out [OH-] - use kw to find [H+] -convert [H+]to pH

Question 59

what is the definition of a neutral solution

Answer 59

same amount of H= and OH-, not pH 7

Question 60

how to work out pH of strong bases

Answer 60

use kw, kw/[OH-] = [H+]

Question 61

what is the acid dissociation constant ka

Answer 61

value of kc related to a weak acid = [H+][A-] [HA]

Question 62

how does ka and pka relate to pH

Answer 62

larger the value, the weaker the acid

Question 63

equation for pka

Answer 63

-log Ka

Question 64

what is the inflection range, start pH and end pH for strong acid strong base titration curve

Answer 64

3-10 ~1 ~12

Question 65

what is the inflection range, start pH and end pH for strong acid weak base titration curve

Answer 65

3-8 ~1 ~8-11

Question 66

what is the inflection range, start pH and end pH for weak acid strong base titration curve

Answer 66

6-10 ~3 ~12

Question 67

what is the inflection range, start pH and end pH for weak acid weak base titration curve

Answer 67

no major inflection ~3 ~8-10

Question 68

how must weak acid weak base titrations be measured

Answer 68

using a pH probe

Question 69

What makes a suitable indicator for a titration

Answer 69

changes colour completely within the inflection range of the titration due to only one drop have a clear and obvious colour change

Question 70

what is a buffer

Answer 70

a solution which resists pH changes when a small volume of acid or alkali is added to it

Question 71

what does an acid buffer contain

Answer 71

a weak acid and one of its salts

Question 72

How can a buffer resist pH changes

Answer 72

acid equilibrium shifts to compensate for change in H+ or OH-

Question 73

what does a basic buffer contain

Answer 73

a weak base and one of its salts

Question 74

other than adding a conjugate salt, how else can buffers be made

Answer 74

taking a weak acid and adding small amount of strong base or viceversa