Unit 4 Quiz 3 - Enthalpy, entropy, and Free Energy

What is enthalpy?

The heat transferred from a particular process

What is entropy?

The change in disorder of a physical or chemical process, measured in J/mol K

Substances with _____ disorder are more likely to interact than substances with _____ disorder

high disorder; low disorder

The universe prefers systems with ____ entropy

with high entropy

Equation for entropy

Sum of entropy of reactants - sum of entropy of products

What happens as you transition from the solid, to liquid, to gas phase?

You increase entropy as disorder increases; delta S >0 (+delta S)

What happens when you transition from a gas, to a liquid, to a solid?

You decrease entropy because disorder decreases; delta S<0 (-delta S)

What is thermodynamically favorable?

Processes that occur without outside intervention or help —> spontaneous reactions

if delta G < 0 (-delta G) then

the reaction is favorable( no external effect is required)

if delta G > 0 (+delta G) then

the reaction is unfavorable (external effect is required)

if delta G = 0 then

the reaction is at equilibrium

First equation for delta G

delta H - T * delta S

Second equation for delta G reaction (given G of each substance)

sum of delta G of products - sum of delta G of reactants

When is a reaction ALWAYS favorable(- delta G)?

When it is exothermic (-delta H) that increases disorder (+delta S)

When is a reaction NEVER favorable(+ delta G)?

when it is an endothermic process (+ delta H) that decreases disorder (- delta S)

When is a reaction favorable only at high temperatures?

When it is endothermic (+ delta H) and increases disorder (+ delta S)

When is a reaction only favorable at low temperatures?

when it is exothermic (- delta H) and decreases disorder (- delta S)

When does temperature matter?

When enthalpy and entropy are in competing directions, as it will then determine the overall charge of delta G( and if reaction is favorable)

What does an unfavorable reaction indicate(- delta G)?

it indicates that the reverse reaction is favored