Solubility and Equilibrium Flashcards
Electrolyte strength reflects…
- the NUMBER OF IONS that can be formed from an electrolyte in an aqueous solution.
- strong electrolytes fully ionize
- a solution that conducts electricity
General examples of weak electrolytes
- weak acids/bases that are not fully ionized/dissociated
- salts that are weakly soluble
To know for the solubility guidelines: what are acetates, bicarbonates, perchlorates
acetates C2H3O2-
bicarbonates HCO3-
perchlorates CLO4-
Characteristics of water
- unusually high boiling point (100C @ 1atm)
- Density of solid is less than liquid
- high specific heat capacity
- polar solvent
When 2 aqueous solutions are mixed…
1 - identify whether a precipitate will form. If not, no reaction.
2- write a MOLECULAR EQUATION - balanced equation, including states
3- write TOTAL IONIC EQUATION - spare species into anions and cations
4- Write NET IONIC EQUATION - cancel any spectator ions (dissolved ions that are in both sides of the equation)
What is represented by the equilibrium constant, K?
- determines amount of products formed
- unitless ratio of product to reactant activities, a, at equilibrium.
How to calculate K for general aqueous or gas phase reactions
K=
concentration/pressure of products (to the power of their stoichiometric coefficients) multiplied together
divided by
concentration/pressure of reactants (to the power of their stoichiometric coefficients) multiplied together
** for gasses, P in bar
** for solutions, C in mol/L
-Don’t include solids or liquids in expressions
What does the magnitude of the equilibrium constant, K, tell us?
- Very small: mostly reactants, reaction barely proceeds
- Intermediate: mix of reactants/products
- Very large: mostly products, reactions goes to completion
what is Kow?
Octanol-water partition coefficient
measures the lithophilicity/hydrophobicity of a solute
Large Kow and log(Kow) = highly lithophilic/hydrophobic
3 characteristics of Persistent Organic Pollutants (POPs)
- Persistant (resist transformation)
- Toxic (ex. carcinogen)
- Bioaccumulate (concentration in fatty tissues) - log(Kow) used to measure this
Define Le Châtelier’s principle
When an equilibrium system is subject to stress, system responds by attainting a NEW EQUILIBRIUM that partially offsets the stress.
STRESS = change in temperature, pressure, concentration of a reactant or product
How does change in volume effect a system at equilibrium?
REDUCE V/increase partial P = favours direction that produces LESS moles of gas
INCREASE V/decrease partial P = favours direction that produces MORE moles of gas
How does change in temperature effect a system at equilibrium?
RAISE T = favours direction of ENDOTHERMIC reaction
LOWER T = favours direction of EXOTHERMIC reaction
NOTE
Equilibrium constants change with temperature
Define Q
- reaction quotient
- ratio of products to reactants at any given instant
- not a constant , can take on any value
- calculated the same way as K, but with the current pressure or concentrations in the reaction
Describe the effects of different relationships between K and Q
Q>K reaction shifts LEFT
Q