Karteikarten
SCH4U Equilibrium
Karten in diesem Stapel (22)
- 1Quantitative reaction- reaction in which virtually all of the limiting reagent is consumed
- only forward reaction
- yields only products - 2Reversible reaction- reaction can proceed in both the forward and reverse directions
- 3Dynamic equilibrium- rate of the forward and reverse reactions are balanced
- amount of reactants created = amount of products created
- doesn't mean nothing is happening!
- ex: standing in the middle of a moving elevator; you have to put in work to stay there, but you're at a constant point
-ex: when the rate of condensation>rate of evaporation, its raining. if rate of evaporation>rate of condensation, the air is dry. If they're equal, air is comfortable --> this is dynamic equilibrium - 4Systems at equilibrium- macroscopic properties (colour, pH, etc) are constant
- closed system such that no external reactions occur and no matter is lost
- forward rate=reverse rate, established in either direction - 5Achieving equilibrium- Starting with only product: [product] decreases to a constant, [reactant] increases to a larger constant at which point the curves of each concentration are parallel
- starting with only reactant: [reactant] decreases to a constant, [product] increases to a smaller constant
- starting with both: [product] increases to a constant, [reactant] increases to a smaller constant - 6Equilibrium constant- Keq
- determined by writing an equation [products]/[reactants] with stoichiometric molar ratios as exponents
- in the forward direction its K, and in the reverse direction its the reciprocal (1/k) - 7Steps to solve problems involving equilibrium constants1. write the balanced equilibrium equation
2. create an ICE table & fill out
3. use stoich to deduce unknowns in the table - 8DINK rule- a million dollars + a nickel is still basically a million dollars
- When adding, if the difference between Keq and initial concentrations is very large (magnitude of 10^3 or more) we can eliminate the addition/subtraction and write DINK - 9Homogeneous vs heterogeneous reaction- homo= reactants and products are all in the same phase/state
- hetero= reactants and products are in different phases/states - 10Reaction quotient- Q
- Represents the same ratio as Keq, just not at equilibrium
- if Q>K, there are more products than reactants; equilibrium shifts left to consume it
- if Q - 11Le Chatelier's Principle- When a chemical system at equilibrium is disturbed by a stress, the system adjusts/shifts to oppose the change
- Stress can be change in concentration of any species, change in temp or volume, etc - 12Increasing [reactant]/ decreasing [product]- causes the equilibrium to shift right (toward products) to consume the reactant/increase the amount of product
- 13Increasing [product]/decreasing [reactant]- causes equilibrium to shift left to consume excess product/to yield more product and make up for what's missing
- 14Increasing volume (decreasing pressure)- causes less frequent collisions between particles
- shifts toward the side with more moles of gas in order to increase collision frequency - 15Decreasing volume (increasing pressure)- increases number of collisions
- shifts to side with fewer moles to reduce number of collisions - 16Changes in temp for exothermic systems- energy is released
- increasing temp is like increasing product concentration; equilibrium shifts left
- decreasing temp is like decreasing product concentration; equilibrium shifts right - 17Changes in temp for endothermic systems- energy/heat is absorbed
- increasing temp is like increasing reactant concentration; equilibrium shifts right *more energy available to be absorbed
- decreasing temp is like decreasing reactant concentration; equilibrium shifts left - 18Variables that don't affect position of equilibrium- catalyst; speeds up the forward and reverse reaction the same amount. this decreases the time required to achieve equilibrium, but not the position of it
- inert gases; increases the pressure, which increases the rate, but once again only affects how quickly equilibrium is reached - 19Solubility rules- salts = more soluble in hot water
- gases = more soluble in cold water
- alkali metal salts are very water soluble
- ammonium salts are very water soluble
- Salts containing the nitrate ion are very water soluble
- Salts containing Cl, Br and I etc. ions are soluble. A salt containing Ag or Pb (2+) is not soluble - 20Dissolving a salt/precipitation- ionic compound in a crystal lattice structure
- metal cation bound to nonmetal anion
- dissolution = example of equilibrium
- Cations and anions attract, but also attract to the poles of water
- If the intermolecular forces within the salt crystals exceed the strength of the dipole-dipole force, the salt won't dissociate, but if they intermolecular forces are weaker then it will
*solubility table tells us which are stronger/weaker
- If the IMFs are weaker, then at first, only dissociation occurs
- eventually once there are ions present in the solution, the ions collide with each other/the remaining crystal and are pulled back together to form a new crystal
- this is precipitation
- - 21Saturated vs unsaturated- when the rate of dissociation of a salt = rate of precipitation, the system is at equilibrium
- this is a saturated solution; there is no change in concentrations or amount of precipitate present
- unsaturated = rate of dissociation is greater than ppt'ion
- supersaturated= rate of ppt'ion > rate of dissociation - 22Common ion effect- introducing a common ion (a compound which contains an ion that's a product in the reaction) shifts the equilibrium toward the reactants, making more solid salt
Informationen
- Beschreibung
- Karteikarten am SCH4U Equilibrium, erstellt von Isabelle Poulin am 16/06/2018.
- Erstellt von
- Isabelle Poulin
- Aufrufe
- 0
- Bewertung