Dissolving

when is a solution formed

when a substance known as a solute is dissolved in another substance known as the solvent

what is solubility

the relative amount of substance that will dissolve

what does solubility depend on

* the relative strength of the attraction between solvent and solute particles
* the strength of attraction between the solute and solvent particles in the mixture

what does separating particles do in terms of energy

requires energy

what does creating new forces of attraction do in terms of energy

it release energy

what makes dissolving more likely to occur

* if more energy is release when the new attractions form than that needed to separate the particles in the solvent and solute

what makes it more likely to form solutions

substances with similar forces of attraction between their particles

what must occur in order for an ionic solid to dissolve

* the strong ionic bonds holding the ions together in the solid must be overcome


* along with the intermolecular forces of attraction between the water molecules

how do ionic solids dissolve

* the ions are spread among the water molecules
* the polar water molecules are attracted to the ions at the surface of the solid

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what happens to the cations and anions when being dissolved in water

* the cations are surrounded by water molecules (negative ends pointing towards the ion)
* the anions are surrounded by water molecules (positive ends pointing towards the ion)
* these separated ions are then surrounded by water molecules to form hydrated ions

what causes the ionic solid to dissolve in water

if the ion-water attractions are stronger than the total of the ion-ion attractions plus the attractions between the water molecules

diagram of polar water molecules being attracted to ions

pg. 147

what causes different ionic compounds

the amount of energy required to break up an ionic lattice and separate the water molecules (so hydrated ions can be produced)

when are ionic compounds insoluble

if more energy is required to separate the ions and water molecules than can be gained by formed hydrated ions

why are compounds containing non-polar molecules less likely to dissolve in water (and other polar solvents)

if the attraction between the polar solvent molecules and the non-polar solute molecules is not very strong compared to the attraction between the solute molecules and the solvent molecules

why may compounds containing non-polar molecules in a non-polar solvent dissolve

if the attractions between the molecules in the solute, the solvent and in the solution are all weak attractions \`