kinetics and equilibrium Flashcards
kinetics
deals with the rates of chemical reactions
rate
describes how fast a reaction takes place
* high rate = fast (less time)
* low rate = slow (more time)
collision theory
for reactions to occur reactant particles must collide.
1) spatial orientation must be exact
2) activation energy must be met
factors affecting reaction rates
temperature
an increase of temp, increases the reaction rates, due to more KE
factors affecting reaction rates
concentration
the greater the concentration (M) of reactants, the great the reaction rates
factors affecting reaction rates
nature of reactants
ionic substances react faster (dissociate) than covalent ones (larger and contain more bonds)
factors affecting reaction rates
surface area
increase in surface area, increases the reaction rate because more surfaces are exposed
* keyword = powder
factors affecting reaction rates
pressure
increasing pressure on gases, increases the reaction rates bc it increases the concentration of the particles
* little to no effect on liquids and solids
factors affecting reaction rates
catalyst present
increases the reaction rate by lowering the activation energy and creates an alternate pathway
potential energy
is the energy stored within the bonds of reactants and products of a reaction
heat content (heat of reaction)
the amt of heat absorbed or release in a chemical reaction
*formula: heat of reaction = PE(products) - PE(reactants)
endothermic reactions
gain more energy than is released
- energy of the products is higher than the reactants
- energy is absorbed
- heat of reaction is POSITIVE
exothermic reactions
more energy is lost to the surroundings
- products have less energy than reactants
- energy was released
- heat of reaction is NEGATIVE
surrounding temperature
exothermic reactions
release energy so the surrounding temp (outside the reaction) gets warmer/hotter
- ex: heat pack, or dissolving of NaOH, LiBr
surrounding temperature
endothermic reactions
absorb energy so the surrounding temperature get colder/cooler
- ex: cold pack, or dissolving of NH4Cl, KNO3, NH4NO3
equilibrium
is the state of balance between 2 opposite reactions occurring at the same time
- most reactions are reversible
- must take place in a closed system
- state of equilibrium is dynamic = changing
equilibrium is reached when the reaction rates (forward and reverse)…
…are EQUAL
- are the same
at equilibrium the concentration of reactants and products…
…are CONSTANT
- staying the same
point of equilibrium is affected by:
- temperature change (delta t)
- change in concentration
- change in pressure (on gases only)
a reaction is NON-REVERSIBLE when:
1) a product is removed
2) a product is a gas and the gas escapes
3) a product is a precipitate (insoluble product) and cannot react again
- (s) = solid
- double replacement
4) a product is H2O
types of physical equilibrium
1) phase equilibrium
- at 0°C in a closed container, both water and ice exist at the same time
ex: H2O (s) ⇌ H20 (l) - at 100°C in a closed container, both liquid and gas exist at the same time
ex: H20 (l) ⇌ H20 (g)
***THIS OCCURS IF TEMP IS CONSTANT
types of physical equilibrium
2) solubility
mass of a solute (solid) which can dissolve in a given amount of solvent
- rate dissolving = rate recrystalizing
- solution is SATURATED (table G; point is on the curve, and indicates equilibrium)
