2.1 Flashcards
Solutions: what are mixtures?
- most natural substances
- have variable composition
- retain component properties
what is a solution?
- homogenous mixture (uniform distribution) of 2 or more substances in A SINGLE PHASE
Gas and solid solutions what happens?
- gases completely miscible (be able to mix)
- gas dissolved in solid: occupies spaces in solid lattice eg. H2 in Pd
What is an alloy?
solid solution of metals ( a metal made by combining 2 or more metallic element)
true or false: substances with similar types of intermolecular forces will dissolve in each other
true
The solution process: what are the factors which determine whether a substance dissolves
enthalpy- exothermic favors dissolving
entropy- always favors solution formation ( solutions form naturally; not pure substances)
true or false: energy required to separate particles
true
true or false: energy released when particles mixed and new attractions form
true
What does delta H soln stand for?
Heat of solution: it = the total enthalpy change when solution forms from pure solvent and pure solute
What does forming a solution involve?
- ) solute particles separate - endothermic
- ) solvent particles separate - endothermic
- ) solute + solvent particles mix - exothermic
express delta H solution = ….
overall enthalpy change - reflection of strength of intermolecular attractions
delta H solution = delta H solvent + delta H solute + delta H mixture
What are the heats of solution measured by?
calorimeter
true or false: When the delta H solution is highly positive, it is likely that the solute is highly insoluble
true
What does hydration mean?
solvation in water
true or false: solvation of ions in water is always exothermic
true
delta H hydration =….
delta H h20solvent + delta H mix
what is delta H hydration related to?
- charge density of ion
- distance between ion and dipole
why does the higher the charge the more negative the delta H of hydration?
water molecules can experience a greater magnitude and attraction to ion
why does the smaller the ion the more negative the delta H of hydration
the closer the ions can come to the water
What does lattice energy mean?
it is the amount of energy required to separate a solid ionic compound into GASEOUS IONS
express delta H solution when ionic compound is dissolved in water
delta H soln = delta H solute + delta H hydration
define solubility
maximum amount of solute THAT WILL dissolve in a solvent at a certain temperature
What are solutions classified as?
saturated and supersaturated
Define saturated
contains maximum quantity of dissolved solute in presence of solid( at that temperature) ; if we add anymore will not dissolve anything
define super saturated
contains more solute than equilibrium amount of solute dissolved is unstable
what happens to solutions at equilibrium?
for solid in solution with time:
rate of dissolving = rate of crystallization
What are the factors which affect rate of dissolution
solvent molecules must make contact with solute
rate of dissolution increased by:
- increasing surface area of solute (also stirring)
- increase temperature
definition of dissolution
is the process in which a solute forms a solution in a solvent
true of false: most ionic solids are more soluble at higher solvent temperatures
true
Does increasing the temperature usually increase the amount of solute that dissolves to give a saturated solution
yes
what does henry’s law state
that the solubility of gas in liquid is proportional to gas pressure
Express henry’s law
Sg= KhPg
what does Sg mean?
solubility of gas in liquid (mol L-1)
what does Kh mean?
henry’s constant (mol L-1 atm-1)
what does Pg mean?
partial pressure of gas above solution (atm)
the relationship of temperature and solubility
as solvent temperature increases, gas solubility decreases
think of cold water
