Water and Solutions Flashcards
Define Latent Heat of Fusion
The energy required to convert one mole of a substance from a solid to a liquid at its melting point
Define Latent Heat of Vaporisation
The energy required to convert one mole of a substance from a liquid to a gas at its boiling point
Define Specific Heat Capacity
The energy required to raise the temperature of 1g of a substance by 1 degree Celsius
Define Density
A measure of the mass of a substance per unit volume (eg g/L)
Define Solubility
The degree to which a given solute will dissolve in a given solvent. Often expressed quantitatively with the units ‘g/100g solvent’
Dissolution
The process of dissolving. Called dissociation for ionic compounds (as the ions ‘dis-associate’)
Miscible
Refers to two liquids which can mix together readily (opposite = immiscible)
Solvation
The process of water molecules surrounding a solute molecule or ion and bonding with it
Ionisation
A reaction between a molecule (eg an acid) and water, resulting in the formation of two dissolved ions
Suspension
Where a solid substance is dispersed in a solvent but not dissolved. The solid particles are distinguishable from the solvent particles. Suspensions usually settle over time and the solid can be separated by filtration.
Colloid
A stable suspension, which will not settle over time
Ion-dipole force
An attractive force between an ion and the oppositely charged pole of a polar molecule (such as water)
Ionic Equation
A chemical equation in which the ‘spectator ions’ are omitted.
ppm
A unit of concentration referring to ‘parts per million’: the concentration of a dissolved solute with the effective units of mg/L (in water) or micrograms per gram of solvent.
%w/w
Concentration of a dissolved solute with the effective units of g/100g solvent
%w/v
Concentration of a dissolved solute with the effective units of g/100mL solvent
%v/v
Concentration of a dissolved liquid solute, with the effective units of mL/100mL solvent
Solubility Curve
A graphical depiction of how the solute concentration required to form a saturated solution changes across a range of temperatures
Saturated Solution
A solution in which the maximum amount of solute is dissolved, at that temperature
Unsaturated Solution
A solution in which less than the maximum amount of solute is dissolved, at that temperature
Supersaturated Solution
A solution in which more than the maximum amount of solute is dissolved, at that temperature. This is an unstable situation which can arise when a saturated solution cools, and is likely to result in crystallisation of some of the solute
Crystallisation
Where a dissolved solute forms a solid due to it being in a supersaturated solution. This often arises due to the cooling of a saturated solution; the slower the solution cools the larger the crystals appear.
