Thermodynamics (1) Flashcards
Anabolism
Biochemical reactions that make larger molecules from smaller subunits (ex. dehydration synthesis reactions).
Catabolism
Biochemical reactions that break-down large molecules to make smaller subunits (ex. hydrolysis reactions).
Metabolism
All biochemical reactions that take place within an organism.
Energy
The ability to do work (move an object) or heat an object, measured in Joules (J) or kilocalories (kcal).
Kinetic Energy
The energy of an object is due to its motion.
Potential Energy.
The energy that is stored in an object due to its relative position, charge, or stress
First Law of Thermodynamics (Law of Conservation of Energy)
Energy cannot be created nor destroyed; only converted from one form to another. (Energy Into System Energy Out of System)
Enthalpy (H)
The total energy (sometimes called heat) content of a substance.
ΔH
The change in the amount of heat in a reaction system as reactants turn into products.
Exothermic Reaction
A chemical reaction that overall releases energy. ΔH is a negative value
Endothermic Reaction
A chemical reaction that overall absorbs energy. ΔH is a positive value
Entropy (S)
The amount of disorder/randomness in a system.
ΔS
The change in entropy of a system as reactants turn into products.
Second Law of Thermodynamics
Reactions that increase the entropy (ΔS > 0) of the universe are favoured.
Spontaneous Reaction
A reaction that will occur on its own without an external source of energy.
What is Gibbs Free Energy (G) and how is ΔG calculated?
Gibbs Free Energy (G) is the useful (free) energy within a system. The change in free energy (ΔG) is calculated as:
ΔG =ΔH−T ΔS
where:
ΔG = free energy change (J)
ΔH = enthalpy change (J)
T =temperature (K)
ΔS = entropy change (J/K)
Q: What do the values of
ΔG indicate about a reaction?
ΔG<0: Reaction is exergonic (spontaneous).
ΔG>0: Reaction is endergonic (not spontaneous) and requires an external energy source.
ΔG=0: Reaction is at equilibrium.
what does this picture represent:
endergonic reaction requires an external energy source to complete. Overall, it absorbs energy.
what does the picture represent:
exergonic reaction does not require an external energy source to complete. Overall, it releases energy.
Q: How does the ΔG of cellular respiration relate to energy production?
Cellular respiration has
kJ/mol
ΔG=−2870kJ/mol, making it a spontaneous process that releases energy from glucose. This energy is used to synthesize ATP, a more readily available energy source for cells.
How does the ΔG of photosynthesis relate to energy absorption?
Photosynthesis has
ΔG=2870kJ/mol, making it a non-spontaneous (endergonic) process. It absorbs energy from sunlight to synthesize glucose.
What is the ATP-ADP cycle?
The ATP-ADP cycle is how cells get and use energy. ATP loses a phosphate to become ADP, releasing energy for the cell to use. ADP is then turned back into ATP using energy from food.
What happens when ATP is used to provide energy?
When ATP provides energy, it is coupled with another reaction that uses the released energy to perform work or drive the process forward.
