Electrochemistry

Does spontaneity determine the speed of a reaction?

No, determining spontaneity is not the same as determining rate of reaction (kinetics)

Four factors that spontaneity is dependent on.

Enthalpy (ΔH), Temperature, Entropy (ΔS), and Gibbs Energy (ΔG)

What are microstates

Micro states are the number of possible arrangements for molecules in a system

More micro destates =

More entropy

What do you need to watch out for/decide with enthalpy of fusion?

You need to pick a sign for enthalpy of fusion → if melting → enthalpy is positive (system gains heat), if freezing→ enthalpy is negative (system loses) heat

What conditions always make a system therm. favorable

if enthalpy is negative (-ΔH) and Entropy is positve (+ΔS),

than Gibbs Energy will always be negative (-ΔG)

What force drives the spontaneity if -ΔH and -ΔS

the rxn is drive by Enthalpy (ΔH), and you want a low temperature for for -ΔG

What force drives the spontaneity if +ΔH and +ΔS

the rxn is drive by Entropy (ΔS), and you want a lhigh temperature for for -ΔG

What force drives the spontaneity if +ΔH and -ΔS

This reaction will always never be thermodynamically favorable

What is ΔG at equilibrium (phase changes)

ΔG = 0

What is ΔG when reaction is spontaneous

ΔG < 0

What is ΔG when reaction is not spontaneous

ΔG > 0

How does adding a catalyst affect ΔG

It has no effect

How to solve Gibbs energy calculations w Hess’s Law

manipulate the equations given to match need and add up the values

does breaking bonds absorb or release energy?

breaking bonds absorbs energy (+ΔH)

does forming bonds absorb or release energy?

forming bonds releases energy (-ΔH)

Is the value of K greater, less than or equal to 1 at equilibrium WHEN the system is therm. favorable

K>1