Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CHEM > Module 2: Energetics, Rates and Driving Forces of Chemical Reactions > Flashcards

Module 2: Energetics, Rates and Driving Forces of Chemical Reactions Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

Which factor, when increased, will increase the rate of any reaction?

A

Temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In the rate law, k is constant for a given ___?

A

T temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Three factors which affect rate (collision model)

A

Collision rate
Collision effectiveness
Collision orientation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why are the terms [A] and [B] in the rate law?

A

Higher concentrations increase collision rate, and therefore reaction rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Activation energy

A

The minimum energy required for breaking and forming bonds in a collision for successful reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When Gibbs energy is negative, is energy still required for an effective collision?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Boltzmann distribution (energy of molecules)

A

Distribution of kinetic energy is exponential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which quality of a molecule will increase the number of collisions with correct orientations?

A

Symmetry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which properties will molecules with low chances of correct collision orientations possess?

A

Lots of different functional groups (no symmetry) hard to get correct orientation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Molecularity

A

Number of molecules that have to collide for a successful reaction

A way to classify elementary reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Three classes of molecularity

A

Unimolecular
Bimolecular
Termolecular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which molecularity is very unlikely to cause successful collision?

A

Termolecular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Transition state

A

Loosely bound complex containing party broken and partly formed bonds

Only exists for a short time and cannot be isolated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

‡

A

Transition state denotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

k = Ae^(-Ea/RT)

A

Arrhenius equation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

k = Ae^(-Ea/RT)

What do these symbols stand for?

A 
k is rate constant
A is frequency factor
e is an exponential
Ea is activation energy
R is gas constant (8.314 J K^-1 mol^-1)
T is temperature
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In the Arrhenius equation
k = Ae^(-Ea/RT)

Which factors will increase k, and which will decrease k?

A

Increase: A (frequency factor) and T (temperature)

Decrease: Ea (activation energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the two approaches of determining Ea or A

A
  1. Use natural log version of Arrhenius equation. Take T and k at two different points and substitute
  2. Measure T and k at lots of points and plot a graph of lnk vs 1/T
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Redox reaction

A

Reduction oxidation reaction in which electron transfer occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Ionic compound

A

Compound made of two or more ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Oxidation

A

Loss of electrons- resulting in a positive change in oxidation number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Reduction

A

Gain of electrons- resulting in a negative change in oxidation number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Oxidation number

A

A way of identifying oxidation and reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

When atoms exist as elements, what is their oxidation number?

A

Zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the oxidation number of a monatomic ion?

A

The same as the charge on the ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Oxidation number of hydrogen in compounds

A

+1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the oxidation number of oxygen in compounds? What is the exception?

A

+2

Exception is H2O2 hydrogen peroxide: -1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What can we infer about the oxidation numbers of atoms within a molecule?

A

The sum is zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What can we infer about the oxidation numbers of atoms in a poly atomic ion?

A

The sun is equal to the charge on the ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Half equation

A

Equation of one species in a redox reaction

They add together to give total reaction equation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What must both half reactions have in common?

A

Same number of electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Oxidising agent

A

Species which is reduced by gaining electrons- oxidises other species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Reducing agent

A

The species which is oxidised by losing electrons- reducing the other species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What must exist for a redox reaction to occur?

A

A potential difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Units of potential difference

A

J C^-1

Joules per coloumb
Energy per unit charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Reduction potential

A

A substance’s potential to attract electrons

37
Q

What decides which species will gain electrons in a redox reaction?

A

The reduction potential. The species with highest (most positive) reduction potential will gain electrons.

38
Q

Equation for overall potential difference

A

E reaction = E reduction process - E oxidisation process

39
Q

What will the overall potential difference be for a spontaneous reaction?

A

Positive

40
Q

Purpose of galvanic cells

A

To measure potential difference in a redox reaction

41
Q

How do galvanic cells measure potential difference?

A

They separate the half reactions into two half cells and measure the electron transfer through the wire with a voltmeter

42
Q

Two electrodes

A

Cathode

Anode

43
Q

What does a salt bridge in a galvanic cell do?

A

Allows migration of ions between the cathode and anode

44
Q

What occurs at the cathode?

A

Reduction

45
Q

What occurs at the anode?

A

Oxidation

46
Q

What indicates which electrode of a galvanic cell contains the reduction process?

A

The sign of the overall cell potential

47
Q

Equation for overall cell potential

A

E cell = E RHS - E LHS

48
Q

SHE

A

Standard hydrogen electrode

A reference electrode used to find the sign and magnitude of individual reduction potentials in a galvanic cell

49
Q

What is the reduction potential of a SHE?

A

0.00V

50
Q

Is SHE the anode or cathode?

A

Can act as either

51
Q

E(standard) reaction = RT/nF lnQ

What does n stand for?

A

Number of electrons transferred

52
Q

How do we find which species is being reduced in a redox reaction?

A

See which reduction potential is more positive

53
Q

How do we balance electrons in half equations?

A

Multiply equations to get same number of electrons

54
Q

How to find E(standard) reaction?

A

Subtract oxidation reduction potential from reduction reduction potential

55
Q

When do we use E reaction instead of E(standard) reaction?

A

When conditions aren’t standard e.g. concentrations not 1 mol L^-1

56
Q

Which reduction potentials depend on pH?

A

Those involving complex ions like MnO4^-1

57
Q

Four steps for balancing redox equations

A

Balance for non oxygen and hydrogen ions

Balance oxygens by adding H2O molecules

Balance hydrogens by adding H+ ions

Balance charges by adding electrons

58
Q

If H+ ions are present in a solution, what happens to E reaction if pH is increased?

A

Concentration of H+ ions will increase, therefore Q will change, and so will E reaction

59
Q

What do the concentration of H+ ions ins a solution if pH=4?

A

1 x 10^-4

60
Q

Biological standard state

A

All species at 1 mol L^-1 concentrations

Except H+ which is at 1 x 10^-7 mol L^-1

61
Q

If we know E cell and reduction potentials, what can we find?

A

Concentrations

62
Q

Ion selective electrode function

A

Can be used to measure concentration of specific ion in a solution

63
Q

Concentration cells

A

Galvanic cell that contains the same species in each half cell at different concentrations

64
Q

Do electrons flow when the half cells contain the same ions?

A

Yes- concentrations influence reduction potential of total cell

65
Q

When writing half equations for a concentration cell, what must we ensure?

A

Electrons and reduced species cancel on both sides

We are just left with oxidised species on each side

66
Q

When calculating E cell of concentration cells, what is E(standard) cell?

A

0, because at standard conditions, both concentrations at each half cell are 1 mol L^-1

Both cells contain same species, and at same concentrations, there is no difference- electrons won’t flow

67
Q

Value of E cell for spontaneous reaction?

A

Positive

68
Q

Why are ‘chemical’ oxidants not good for biological systems? (3)

A

Toxic
Require low pH solutions
Unselective (will oxidise anything

69
Q

Which groups are oxidised in FAD?

A

N=C oxidised to N-H

70
Q

Which group is oxidised in NADH?

A

C=H oxidised to H-C-H

71
Q

Basic overview of metabolism (food molecules)

A

Food molecules are oxidised in a series of steps and the change in energy is used to perform work.

The electrons from these reactions are passed from oxidant to oxidant until they are given to O2.

72
Q

Transition metal oxidants

A

Biological oxidants based on transition metal ions

73
Q

Cytochromes

A

Iron-containing molecules in which the iron atom can undergo the oxidation

74
Q

Enzymes that contain transition metal ions do what?

A

Catalyse redox reactions

75
Q

Ligand

A

A molecule or ion in which one or more donor atoms have a lone pair of electrons

76
Q

A ligand is a Lewis ____?

A

Base (electron pair donor)

77
Q

The transition metal ion is a Lewis _____?

A

Acid (electron pair acceptor)

78
Q

What do ligands bond to and reduce?

A

Transition metal cations

79
Q

Most common donor atoms of a ligand (2)

A

Nitrogen and oxygen

80
Q

Metalloproteins

A

Proteins in which donor atoms bond to transition metals in R groups of amino acids

81
Q

In a metalloprotein, the ligand is the ____?

A

Amino acid

82
Q

How does a metal ion get close to the R groups of amino acids?

A

A chain of proteins can fold itself to bring the side chains of its amino acids closer to the ion

83
Q

Heme-based ligand

Other name?

A

Four nitrogen atoms arranged in a cyclic shape

Heme

84
Q

What does (L) mean in an equation?

A

Ligand

85
Q

What do ligands change about the metal ion they bond to?

A

It’s reduction potential

86
Q

What determines the change in reduction potential of the metal ion by the ligand?

A

Their relative electron densities

87
Q

List the cytochromes in order of reduction potentials

A

b
a
c

88
Q

Which cytochrome attracts electrons the most?

A

Cytochrome c

CHEM (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions