Thermodynamics Flashcards
Define system.
easily measured & controlled. Matter, energy, work or a combination may cross the boundary.
Define closed system.
only work & energy can cross the boundary.
Give the First Law of Thermodynamics.
energy can neither be created nor destroyed / the energy (U) change of a system is defined as the difference between the heat (Q) absorbed by the system from the surroundings and the work (W) done by the system on the surroundings.
Work =
force x distance moved
Give the Second Law of Thermodynamics.
‘The total entropy of any isolated thermodynamic system tends to increase over time, approaching a maximum value.’ – a law of statistics.
An isolated system allows…
no transfer of matter, energy or work across the boundary.
Define entropy.
measure of disorder in a system.
Define orderliness.
related to how likely an arrangement is to happen by chance, the more ways it could happen by chance (eg more options for different arrangements), the greater the disorder.
Eqn for a closed system.
deltaS = Sf -Si
Eqn for an isolated system.
deltaU = 0
deltaS > 0
Define the Gibbs fucntion.
combines both the change in entropy in the closed system, and the disorder added to the environment by heat in a single function, so that the entropy change of the isolated system (universe) can be calculated.
Give the Gibbs eqn.
deltaG = deltaH –(T x deltaS) in J mol-1
Entropy is a function of…
concentration.
Define coupled reactions & why they occur.
- life operates far from equilibrium & is well ordered
- this is because extremely favourable reactions are coupled with extremely unfavourable reactions
- relies on the reverse of the unfavourable reaction being very slow in the cell
- cells maintain pools of accessible, favourable reactions that can be used to drive other reactions
