12A.3 Flashcards
when gas is formed from Liquid and Solid what will the total entropy be
positive
if the total entropy is positive the reaction is
thermodynamically spontaneous
what happens when an ionic solid dissolves
- the lattice structure is broken down
- the ions are hydrated
the breakdown of a lattice structure is a
endothermic process
how does the breakdown of lattice structure increase the entropy
even though it’s an endothermic process, the number of moles of the particles increases when the ions are separated so more arrangements so more entropy
the hydration of ions is a
exothermic process
how does the hydration of ions decrease the entropy
even though it is an exothermic process, the hydration of the ions causes the water molecules to become more order as they arrange them selfs around the negative and positive ions causing less disorder so less entropy
the ordering of water molecules (during hydration) is significant when dissolving
Anhydrous salts
the solubility of a solid depends on 3 factors, what are they
- the change of entropy in the system
- the value of H solution (change in)
- T
if the S total of a solid is negative it will be (when reacting with water)
insoluble
if the S total of a solid is positive it will be (when reacting with water)
soluble
If you increase the number of moles the number of particles will
increase
what will happen to S total if the number of moles in the product is more than the number of moles in the reactant
it will increase since more moles mean more particles which means more arrangments which means more entropy
solubility of a metal hydroxide increases
down the group
solubility of a metal sulfate increase
up the group
why does the solubility increase down the group for metal hydroxides
Because as you go down the group the value of change in solution enthalpy becomes more negative giving us a larger value for change in entropy of surroundings, and the entropies of cations become more positive down the group which favors solubility
why are the standard entropies of the hydroxide ion left out of the explanation of the trends in MOH
because the ion is common to all metal metal hydroxides
the trend in the entropies of the hydrated cations mirrors the
the trend in the S system (change in)
why are the standard entropies of the sulfate ion left out of the explanation of the trends in MSO4
because the ion is common amongst all the other MSO4
why are metal sulfates more soluble up the group
as you go up the group the change in the enthalpy of the solution becomes more negative causing the entropy change of the surrounding to be greater, and even though as you go up the group the change of entropy of the hydrated cation increases the change in the entropy of the surrounding would be further greater making it more soluble
