topic 2 - thermodynamics Flashcards
system vs surroundings
system = what we are interested in
surroundings = everything outside the system
what is the difference between an isolated, closed, and open system
isolated = doesn’t exchange matter or energy
closed = exchanges energy only
open = exchanges energy and matter
what type of system is a bio system
open system
- must acquire energy and matter from their surroundings
what types of work are done inside the cell
synthesis of bio molecules
transport of molecules
cell division
motility
what is the 1st law of thermodynamics
energy is neither created nor destroyed
energy can change locations, and into different forms
how does potential energy change inside an atom
as an electron moves closer to the atomic nucleus, PE is converted to toehr types of energy
farther away the e- is from the nucleus = more PE
what type of bonds give molecules the most PE
more covalent bonds = more PE
what happens to PE and KE during mvmt along an electrochemical gradient
relative concen of molecules on each side of the membrane becomes a source of PE (high concen = high PE)
free mvmt across membrane along concen gradient means PE is converted to KE
what is enthalpy
sum of PE and KE in the system
measured as the amount of heat that is released to/absorbed from the surroundings
delta H kJ/mol
what is an exothermic reaction in terms of enthalpy
products have less enthalpy than the reactants
energy released as heat
what is an exothermic reaction in terms of enthalpy
products have more enthalpy than the reactants
energy absorbed
what does it mean if a reaction is spontaneous
reaction can happen under the current set of conditions
energetically favourable
NOT instantaneous (can happen over variety of time frames)
is a reaction is spontaneous then (under the same conditions) it is non spontaneous in the opposite direction
what does it mean if a reaction is non spontaneous
reaction can not occur under the current set of conditions
what are important current conditions for reactions
pH
temp
concentration of reactants and products
pressure
salinity
changes in condition can potentially make the reaction spontaneous in the reverse direction
does enthalpy determine if a reaction is spontaneous
no
exo and endothermic can both be spontaneous
what is entropy
S - measured in J/molK
- how dispersed/spread out the energy of the system and its surroundings is
- everything has entropy
what is the difference in delta H (enthalpy) when heat is released and absorbed
heat released = - delta H
heat absorbed = + delta H
what is the difference in delta S when energy is more and less dispersed
more dispersed = + delta S (spontaneous)
less dispersed = - delta S (non spontaneous - violates 2nd law of thermodynamics)
what is the second law of thermodynamics
total entropy of the unvierse is always increasing
- every transformation must increase the total entropy of the universe
entropy determines spontaneity
can the entropy of the system decrease
yes - as long as the entropy of the surroundings increases to a greater degree (positive change overall)
what does it mean if a reaction is exergonic
- free energy is released
- delta G
- spontaneous
- products have less free energy than reactants
what does if mean if a reaction is endergonic
- free energy is gained
- delta G
- non spontaneous
- products have more free energy than reactants
what is free energy
G - measured in kJ/mol
energy of the system that is available to do work
- for work to occur, the energy must be available to carry out the change (reactants have more energy than the products)
what is the difference in delta G when energy is/isn’t available
energy available = - delta G
energy not available = + delta G
how to calculate delta G (free energy change)
delta G = -T(delta S total)
delta G = delta H - T(delta S system)
when does chemical equilibrium occur
when the rates of the forwards and reverse reactions are equal
- reactions never go to completion
- proportion of reactants and products are constant
what is metabolism
sum of all reactions in a cell
what is catabolism
breaking down of complex molecules
- proteins broken into amino acids
- break down fats/carbs
exergonic (releases chem energy)
what is anabolism
building up of complex molecules
- building muscle, DNA, proteins
overall process = endergonic
indiviudal reactions = exergonic
what is a connected reaction
product of the first reaction is the substrate (reactant) for the second reaction
(first reaction of glycolysis produces G6P and the second reaction uses it)
what are the components of ATP
nitrogenous base - adenine
sugar - ribose
3 phosphates
why does ATP have PE
compressed negative charges in the phosphate groups
what occurs with the breakdown of ATP
breaking ATP bonds with water = hydrolysis
products = Pi, ADP
negative change in delta G (free energy) - spontaneous
what is a coupled reaction
2 reactions that happen at the same time and in the same place
- used to carry out reactions that otherwise would be endergonic (use released free energy from exergonic to drive endergonic)
