IBC Exam 3

R= 8.314 J mol -1 K -1

Universal gas constant

F = 96,487 C/mol e-

Faraday’s constant

What is energy?

the ability to do work

What is kinetic energy?

Energy associated with motion

What is potential energy?

Energy associated with position or composition

What is the 1st Law of Thermodynamics?

The total energy of the universe is constant. Energy cannot be created nor destroyed, only transformed/constant.

What does an open system do?

exchanges mass + energy

What does a closed system do?

exchanges energy but not mass

What does an isolated system do?

exchanges neither energy nor mass

What is heat?

The transfer or exchange of thermal energy caused by a temperature difference

What is ΔH? What unit is typically used?

Enthalpy: heat gained/lost in a reaction at constant pressure; Usually in kJ/mol

What does an exothermic reaction do?

It releases energy to surroundings as heat

What does an endothermic reaction do?

It absorbs energy from surrounding as heat

What is a state function?

A value that only depends on the system’s state, not the path taken

What is ΔE?

The change in internal energy of a system

If system does work, w is ___

negative

If work is done on the system, w is __

positive

If system gains heat, q is __

positive

If system loses heat, q is ___

negative

What does 0<ΔH mean? How about 0>ΔH?

Endothermic reaction (system absorbs heat from its surroundings)
Exothermic reaction (system is releasing heat to its surroundings)

What are the standard states of elements? (gas, temp, solution)

gas- 1atm

temp- 278K (25 degrees C)

solution - 1M

What is potential energy when covalent bond forms? When it breaks?

Potential energy decreases when covalent bond forms (bond stabilizes). It increases when covalent bond breaks.
Bond form=exothermic
Bond breaking=endothermic

What is the relative rate of all reactants consumed and products formed if the equation is:
aA + bB —> cC + dD

Rate = [C]^c * [D]^d / [A]^a [B]^b

What is the rate law when n=0, 1, and 2?

n=0 —> zero order: rate is independent of reactant concentration; M S-1

n=1 —> first order rate is directly proportional to reactant concentration S-1
n=2 —> second order; rate is proportional to [reactant]² M-1 S-1

Rate law is __ vs __

[reactant] vs rate

Integrated rate law is __ vs __

time vs [reactant]

Integrated rate law- Zero order graph x-axis and y-axis

Time vs [A]

Integrated rate law- First order graph x-axis and y-axis

Time vs ln[A]

Integrated rate law- Second order graph x-axis and y-axis

Time vs 1/[A]

When a reaction is exergonic, is it spontaneous or non spontaneous? What is ΔG in this reaction?

Spontaneous; ΔG<0

When a reaction is endergonic, is it spontaneous or non spontaneous? What is ΔG in this reaction?

Nonspontaneous; ΔG>0

What is the general rate law?

Rate=k[A]^n

What is ΔG?

Gibbs Free Energy; The maximum amount of useful work that can be extracted from a system at constant temperature and pressure

Intepretations of ΔG

• ΔG < 0: Spontaneous process (favorable)

• ΔG = 0: Equilibrium

• ΔG > 0: Non-spontaneous process

What is ΔS? What units are typically used?

Entropy; the degree of randomness or disorder in a system; Usually J/mol·K

Interpretation of ΔS

• ΔS > 0: More disorder

• ΔS < 0: More order

What is the 2nd Law of Thermodynamics?

The total energy of the universe always increases in a spontaneous process

What is the 3rd Law of Thermodynamics?

At T= 0K (absolute zero), S=0 and movement of atoms is 0.

Interpretation of K (the equilibrium constant) and Q (reaction quotient)?

When K<Q, the rxn moves toward reactants; when K>Q, the rxn moves towards products

Coenzymes and cofactors: organic or inorganic?

Coenzymes = organic
Cofactor= inorganic

What is the chemical equation of cellular respiration?

C6H12O6 + 6O2 —> 6CO2 + 6H2O

What is the difference between substrate-level phosphorylation vs OXPHOS?

substrate-level phosphorylation: direct binding of phosphate group
OXPHOS: using energy from electrons passed through the ETC and the chemiosmotic gradient

catabolism vs anabolism

cracks molecules apart vs assembles molecules together

What are some common rules for oxidation rates in molecules?

Oxygen is usually -2 and Hydrogen is usually +1

What is the standard notation for a Galvanic cell?

Anode (electrode) | Solution || Solution | Cathode (electrode)

What is cell potential (E naught cell)? How to interpret it:

The measure of the voltage generated by a galvanic cell when the cell operates; driving force for a spontaneous rxn
E naught cell > 0 —> for spontaneous reaction

E naught cell < 0 for non spontaneous reaction

What is e naught?

Reduction potential; amount of drive needed to reduce

What happens in the Warburg Effect?

Cancer cells favor aerobic glycolysis over OXPHOS even in the presence of adequate O2.

Half reaction for standard hydrogen electrode

2H+ + 2e- —> H2

What order is radioactive decay?

Always first order

What is standard reduction potential?

E cell = 0

What is electrolysis?

the use of electric current to stimulate a non-spontaneous reaction

What are the four stages of cellular respiration?

Glycolysis, pyruvate decarboxylation, Krebs cycle, oxidative phosphorylation

List the following for glycolysis:

• Location in a eukaryote

• starting product (with number of carbons)

• ending products (with number of carbons)

• If ATP is produced, substrate-level or OXPHOS? How many?

• cytoplasm

• glucose (6 carbons)

• pyruvate (2 × 3 carbons each, 2NADH)

• substrate-level (2 ATP)

List the following for pyruvate decarboxylation:

• Location in a eukaryote

• starting product (with number of carbons)

• ending products (with number of carbons)

• If ATP is produced, substrate-level or OXPHOS? How many?

• matrix

• pyruvate (2 × 3 carbons each)

• acetyl coA (2 × 2 carbons each), 2 CO2, 2NADH

• NO ATP

List the following for krebs cycle:

• Location in a eukaryote

• starting product (with number of carbons)

• ending products (with number of carbons)

• If ATP is produced, substrate-level or OXPHOS? How many?

• matrix

• acetyl coA (2 × 2 carbons each)

• 4 CO2, 6 NADH, 2 FADH2

• substrate level, 2ATP

List the following for oxidative phosphorylation:

• Location in a eukaryote

• starting product (with number of carbons)

• ending products (with number of carbons)

• If ATP is produced, substrate-level or OXPHOS? How many?

• inner mitochondrial membrane

• 10 NADH, 2 FADH2, O2

• H2O, NAD+, FAD

• Oxidative phosphorylation, 30-32 ATP

Order for electron transfer through the ETC (2 ways)

1. Complex 1 - Q - Complex 3 - Cyt C - IV

2. Complex 2 - Q - Complex 3 - Cyt C - IV

anaerobic respiration vs fermentation

Anaerobic respiration: ETC without O2, uses alternative electron acceptors, moderate ATP field

• produces lactate in animals

Fermentation: No ETC, only glycolysis plus a step to regenerate NAD+

• NADH transfers its electrons directly to pyruvate generating lactate

• produces ethanol in alcohol fermentation