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spontaneous rxns

q : "explain the meaning of spontaneous in a thermodynamic context"
answer is positive delta S total (entropy)

i thought the answer was enthalpy must be negative because its what shows the heat content of the reaction, what has entropy got to do with it????
Reply 1
Avatar for Hunter h
Hunter h
1
its what you have learnt in u4 chemistry. Read your chemistry books and you will find the answer:smile:
Reply 2
Avatar for Pigster
Pigster
20
You obviously haven't studied entropy, yet, or you would know.

Endothermic reactions do take place, e.g. acid + sodium hydrogencarbonate. They happen as there is an increase in entropy - the effect of which is greater than the increase in enthalpy.
Original post by Pigster
You obviously haven't studied entropy, yet, or you would know.

Endothermic reactions do take place, e.g. acid + sodium hydrogencarbonate. They happen as there is an increase in entropy - the effect of which is greater than the increase in enthalpy.

Ok but if the entropy was negative and and delta H postive it wouldnt happen.. So why is entropy considered the main factor???
Reply 4
Avatar for Pigster
Pigster
20
There are two ways of working out spontaneity, Delta G is one way, but it looks like the way you will do is in terms of total entropy change - which includes enthalpy change in the calculation.

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