OD 515 Thermodynamics- Questions Exam 1 with
complete solutions.
What does LIFE represent in terms of energy?
LIFE is a 'big spender' (non-spontaneous, endergonic reactions) and a 'big earner' (spontaneous,
exergonic reactions).
What is the first law of thermodynamics?
The total energy of an isolated system is constant; energy can neither be created nor destroyed,
only transformed or transferred.
What is the second law of thermodynamics?
Energy spontaneously tends to disperse or become more disorderly over time.
What is Gibbs free energy (ΔG)?
Gibbs free energy represents the amount of energy capable of doing work during a reaction at
constant temperature and pressure.
How do endergonic and exergonic reactions differ in terms of ΔG?
Endergonic reactions have a positive ΔG (energy is gained), while exergonic reactions have a
negative ΔG (energy is released).
What is entropy (S)?
Entropy is a quantitative expression for the randomness or disorder in a system.
What does a negative ΔS indicate?
A negative ΔS indicates that the reactants are more disordered than the products.
,What does a positive ΔS indicate?
A positive ΔS indicates that the products are more disordered than the reactants.
What is enthalpy (H)?
Enthalpy is the heat content of the reacting system, reflecting the number and kinds of chemical
bonds in the reactants and products.
What does a negative ΔH indicate?
A negative ΔH indicates that the reaction releases heat and is exothermic.
What does a positive ΔH indicate?
A positive ΔH indicates that the reaction absorbs heat and is endothermic.
What is the equation for free energy change (ΔG)?
ΔG = ΔH − TΔS.
What condition must be met for a process to occur spontaneously?
ΔG must be negative for a process to occur spontaneously.
What is the relationship between K′eq and ΔG′°?
ΔG′° = -RT ln K′eq, indicating whether a reaction is thermodynamically favorable.
What does it mean if K′eq is greater than 1.0?
If K′eq is greater than 1.0, ΔG′° is negative, and the reaction proceeds forward.
What does it mean if K′eq is less than 1.0?
If K′eq is less than 1.0, ΔG′° is positive, and the reaction proceeds in reverse.
, What is the role of autotrophs in energy extraction?
Autotrophs use CO2 from the atmosphere as their sole source of carbon.
What is the role of heterotrophs in energy extraction?
Heterotrophs cannot use atmospheric CO2 and must obtain carbon from their environment.
What drives the flow of electrons in cells?
The flow of electrons is driven by sunlight or metabolic redox reactions.
What is the significance of oxidation-reduction reactions?
Oxidation-reduction reactions involve the transfer of electrons, where one reactant is oxidized
(loses electrons) and another is reduced (gains electrons).
What is the Boltzmann constant?
The Boltzmann constant is k = 1.381 × 10−23 J/K.
What is Avogadro's number?
Avogadro's number is N = 6.022 × 10^23 mol−1.
What is the Faraday constant?
The Faraday constant is F = 96,480 J/V • mol.
What is the gas constant?
The gas constant is R = 8.315 J/mol • K.
What is the unit of ΔG and ΔH?
The units of ΔG and ΔH are J/mol (or cal/mol).
complete solutions.
What does LIFE represent in terms of energy?
LIFE is a 'big spender' (non-spontaneous, endergonic reactions) and a 'big earner' (spontaneous,
exergonic reactions).
What is the first law of thermodynamics?
The total energy of an isolated system is constant; energy can neither be created nor destroyed,
only transformed or transferred.
What is the second law of thermodynamics?
Energy spontaneously tends to disperse or become more disorderly over time.
What is Gibbs free energy (ΔG)?
Gibbs free energy represents the amount of energy capable of doing work during a reaction at
constant temperature and pressure.
How do endergonic and exergonic reactions differ in terms of ΔG?
Endergonic reactions have a positive ΔG (energy is gained), while exergonic reactions have a
negative ΔG (energy is released).
What is entropy (S)?
Entropy is a quantitative expression for the randomness or disorder in a system.
What does a negative ΔS indicate?
A negative ΔS indicates that the reactants are more disordered than the products.
,What does a positive ΔS indicate?
A positive ΔS indicates that the products are more disordered than the reactants.
What is enthalpy (H)?
Enthalpy is the heat content of the reacting system, reflecting the number and kinds of chemical
bonds in the reactants and products.
What does a negative ΔH indicate?
A negative ΔH indicates that the reaction releases heat and is exothermic.
What does a positive ΔH indicate?
A positive ΔH indicates that the reaction absorbs heat and is endothermic.
What is the equation for free energy change (ΔG)?
ΔG = ΔH − TΔS.
What condition must be met for a process to occur spontaneously?
ΔG must be negative for a process to occur spontaneously.
What is the relationship between K′eq and ΔG′°?
ΔG′° = -RT ln K′eq, indicating whether a reaction is thermodynamically favorable.
What does it mean if K′eq is greater than 1.0?
If K′eq is greater than 1.0, ΔG′° is negative, and the reaction proceeds forward.
What does it mean if K′eq is less than 1.0?
If K′eq is less than 1.0, ΔG′° is positive, and the reaction proceeds in reverse.
, What is the role of autotrophs in energy extraction?
Autotrophs use CO2 from the atmosphere as their sole source of carbon.
What is the role of heterotrophs in energy extraction?
Heterotrophs cannot use atmospheric CO2 and must obtain carbon from their environment.
What drives the flow of electrons in cells?
The flow of electrons is driven by sunlight or metabolic redox reactions.
What is the significance of oxidation-reduction reactions?
Oxidation-reduction reactions involve the transfer of electrons, where one reactant is oxidized
(loses electrons) and another is reduced (gains electrons).
What is the Boltzmann constant?
The Boltzmann constant is k = 1.381 × 10−23 J/K.
What is Avogadro's number?
Avogadro's number is N = 6.022 × 10^23 mol−1.
What is the Faraday constant?
The Faraday constant is F = 96,480 J/V • mol.
What is the gas constant?
The gas constant is R = 8.315 J/mol • K.
What is the unit of ΔG and ΔH?
The units of ΔG and ΔH are J/mol (or cal/mol).
