PH1125 - Thermodynamics Flashcards
what do all living things require?
- a continuous supply of energy
what is the relationship between wavelength and energy?
- the shorter the wavelength the higher the energy and vice versa
what does photosynthesis provide to a plant? (2)
- provides chemical energy (ATP)
- stores captured energy as sugars
what do thermodynamics tell us? (3)
- whether a reaction will occur or not
- tell use that a protein will fold
- predict the molecular shape of a drug
- why molecules cross biological membranes
what is the first law of thermodynamics? (5)
- ENERGY CANNOT BE CREATED OR DESTROYED IT IS ONLY INTERCONVERTED
- there are lot of different types of energy
- energy can be changed from one form to another
- during the transformation, energy is neither created nor destroyed
- we can infer the total energy in the universe is constant
what is the equation for the first law of thermodynamics? (4)
- ΔU = Ufinal - Uinitial = q + w
- U is energy
- q is heat absorbed by the system
- w is work done on the system
where is q derived from in the first law of thermodynamics equation ?
- random molecular movement / vibration
what is the formula for w?
- force x distance
what is an exothermic process in term of q?
- releases heat where q is -ve
what are the units for energy? (3)
- J (joules)
- kg m2 s-2
- N m
what is the equation for enthalpy? (5)
- H = U + PV
- H is enthalpy
- U is energy
- P is pressure
- V is volume
what is the second law of thermodynamics? (2)
- the universe is always moving towards maximum disorder
- or in nature the only processes that occur are those for which the entropy remains the same or increases
what is the equation for the second law of thermodynamics? (4)
- S = kB ln W
- S is entropy
- kB is boltzmann constant
- W is the number of ways of arranging a system
in the second law of thermodynamics what happens when temperature rises?
- the structure of any substance becomes more disordered
what is the third law of thermodynamics?
- at absolute zero (0 K) the entropy of a perfect crystalline substance is 0
what is the equation for gibbs free energy? (5)
- G = H - TS
- G is free energy
- H is enthalpy
- T is the temperature (in K)
- S is the entropy
what is the gibbs free energy equation at a constant temperature and pressure?
- ΔG = ΔH - TΔS
what is the difference between enthalpy and entropy?
- entropy is a measure of disorder in a system
- enthalpy is a measure of the overall amount of energy in the system
what does a large ΔS mean in gibbs free energy equation?
- a reaction is more likely to happen
what is the equation for free energy differences?
- ΔG = ∑ΔGf(products) - ∑ΔGf(reactants)
what is the relevance of free energy to pharmacy? (3)
- enzymes are biological catalysts that accelerate most biochemical processes
- enzymes can be thought of as a mechanism for a system to achieve thermodynamic equilibrium
- an enzyme cannot promote a reaction that has a positive ΔG
what happens in ΔG = ΔH - TΔS when ΔG is positive?
- the reaction is non-spontaneous and will not proceed in the forward direction unless coupled with an energetically favourable reaction
What happens when ∆H is -ve and ∆S is +ve? (2)
- the reaction is exothermic and endotropically favoured
- t is spontaneous at all temperatures
What happens when ∆H is -ve and ∆S is -ve? (2)
- the reaction is exothermic but endotropically disfavoured
- only spontaneous at low temperatures
What happens when ∆H is +ve and ∆S is +ve? (2)
- the reaction is endothermic and entropically favoured
- only spontaneous at high temperatures
What happens when ∆H is +ve and ∆S is -ve? (2)
- the reaction is endothermic but endotropically disfavoured
- it is not spontaneous at any temperature
