equilibrium

what is a chemical system

chemicals involved in a rxn

what are the surroundings

anything around a chemical system

what is a closed system

if the chemicals are contained within a space and cannot enter or leave 

what is an open system 

if substances can be added or lost

what is a physical change

products change state and physical properties alter

what is a chemical change

reactants form products with diff physical and chemical properties

what are reversible rxns

rxns where reactants form products and vice versa

are all physical changes reversible

yes 

are all chemical changes reversible

no

what is a forward rxn

reactants forming products

what is a reverse rxn

products forming reactants

what is the reversibility of rxns dependant on 

ea of both forward and reverse rxns

what is the ea

amount of energy required to break bonds of reactants

when are reversible rxns likely to form

when ea of both forward and reverse rxns are low enough that sufficient particles have energy for successful collision

what is dynamic equilibrium

state reached when amount of reactants and products remains constant

what properties are constant at equilbirium

macroscopic properties such as ph, colour and vol

what does adding reactants to a system result in 

fast initial rate of forward rxn that gradually slows as reactants form products 

what does conc change do to a system

rate of forward rxn slows and rate of reverse rxn increases 

when does dynamic equilibrium happen

when rates of forward and reverse rxns are equal and conc of products and reactants are constant

how do we graph rxn rate and time

1. rate of forward rxn is initially high

2. rate of reverse rxn is initially zero 

3. rate of forward rxn will decrease 

4. rate of reverse rxn will increase

5. rates of 2 rxns become equal and equilibrium is reached 

how do we graph conc and time

1. conc of reactants is initially large

2. conc of products is initially zero 

3. conc of reactants decreases, initially quickly then more slowly.

4. conc of products increases, initially quickly then more slowly

5. all concs will plateau when system reaches equilibrium

what is k

mathematical relationship between concs of reactants and products

specific for a particular rxn at a particular temp.

what is included in k

solutions and gases

what is not included in k when the system is heterogenous

solids and liquids

what is included in k when the system is homogenous

solutions, gases, solids and liquids

what does q = k mean

system is at dynamic equilibrium

what does q > k mean

there are more products and less reactants than at equilibrium

what does q < k mean

there are less products and more reactants than at equilibrium

where are the products in k

on top of the fraction

what does it mean if the k value is large

rxn goes toward completion

more products are present than reactants

equilibrium lies to right 

what does it mean if the k value is small

rxn only occurs to small extent

more reactants are present than products

equilibrium lies to left

what does it mean if the k is close to 1

there are significant concs of both products and reactants present.

what is yield

how much product can be produced

what is yield dependant on 

position of equilibrium

what is the yield in rxns with low k values

low yield due to low conc of products