What is a system?
anything of interest to the biologist. Always open in biology(energy and matter can enter and leave the system).
Energy:
Is the ability ti cause change and is needed for a system to do work.
1st law of thermodynamics:
Energy can not be created nor destroyed. Can change location and forms.
Stored energy due to position is called ______________ and energy of the motion/change is called _____________.
Potential energy
Kenetic energy
Where do cells get their energy?
1) High energy electrons: molecules with many non-polar covalent bonds have lots of PE(polar covalent have less).
2) Electrochemical gradient: PE due to difference in concentration across the membrane across the cell membrane.(more difference=more PE)
Enthalpy:
The sum of PE and KE in a system, changes when work occurs. Can either be endothermic, or exothermic.
How is enthalpy measured?
By the amount of heat released and absorbed in a system.
Products having less energy then reactents with a negative deltaH value is a _______________, Reactants having less energy then products with a positive deltaH is a ________________.
Exothermic reaction(released heat to the surrondings)
Endothermic reaction(absorbed heat from the surrondings)
Spontaneous reactions:
A reaction that can occur under the current set of conditions (is cube melting at room temp)
If a reaction is sponataneous can its reverse reaction also be spontaneous in the same set of conditions?
No (an ice cube can not form from water at room temp).
Nonspontaneous reaction:
A reaction that cannot happen in the current set of conditions.
What are important conditions to consider when figuring out of a reaction can be sponataneous?
Temp, pH, concentration of reactants and products, and pressure.
2nd law of thermodynamics:
The total entropy of the universe is always increasing(becoming more disperse). Every transfer of energy increases the total entropy of the universe.
What is entropy:
How dispersed the energy of the system+surrounding is.
How is change in entropy measured:
By the degree to which the energy has changed.
_____________ determines _______________.
Entropy
Spontanaity
When change in entropy(deltaS) is positive the reaction is ____________, when change in entropy(deltaS) is negative the reaction is _____________.
Spontaneous ( more dispersed )
NonSpontaneous ( Less dispersed )
Total entropy:
Change in entropy total = change in surroundings + change in system. * Has to be positive (change in system entropy can be negative if change in surroundings entropy is positive to a larger degree.
Free energy (G)
The measure of the energy in a system that is avaliable to do work(the reactants must have more G then products to do work)
How is free energy measured?
Measured by the amount of energy that was used to do work.
If a reaction is spontaneous:
Free energy(G): is negative + exergonic
Entropy (S): is Positive + energy is more dispersed.
Enthalpy (H): is negative(exothermic)
Metabolism: Catabolic
If a reaction is nonsponatneous:
Free energy(G): is positive + endergonic.
Entropy(S): is negative + less dispersed.
Enthalpy(H): is positive(endothermic).
Metablosim: anabolic
If energy is available:
deltaG is negative and the reaction is exergonic+spontaneous.
If energy is not avaliable:
deltaG is positive and the reaction is endergonic+spontaneous.
