how far? Flashcards
what does it mean when a reaction is at equilibrium?
the rate of the forward and reverse reactions are equal
what are the methods that can be used to measure equilibrium
- measure the change in colour or colour intensity using colourimeter
- use a pH probe
- measure electrical conductivity
- titration (when equilibrium is slow so that titration can be completed before there is much change in e
what does mole fraction mean?
the amount of a given component in a given reaction mixture
state the equation used to calculate mole fractions
mole fraction = number of moles of substance A / total number of moles of all substances
what does partial pressure mean
the pressure exerted by a single species in a reaction vessel
what is the symbol for partial pressure
P
state the equation used to calculate the partial pressure
partial pressure = mole fraction x total pressure
what is the relationship between the concentration of a substance and its partial pressure?
concentration of a substance is proportional to its partial pressure
what are the 3 common units of pressure used in chemistry?
- pascals (Pa)
- atmospheres (atm)
- newtons per square metre
what type of brackets are used in Kc expressions?
square [ ]
what type of brackets are used in Kp expressions?
round ( )
a reaction has the equation:
aA(g) + bB(g) -> cC(g) + dD)g)
what is its Kp expression?
Kp = p(Cc) p(Dd) / p(Aa) p(Bb)
what is the symbol of the equilibrium constant?
K
what does it mean when K is greater than 1?
reaction favours product
what does it mean when K is less than 1?
the reaction favours reactants
what is the effect of increasing temperature on K?
equilibrium shifts to the direction of the endothermic reaction
what is the effect of decreasing temperature on K?
equilibrium shifts to the direction of the exothermic reaction
what is the only factor that affects K?
temperature
what is the effect of increasing temperature on K for a forward endothermic reaction?
K increases as temperature increases
what is the effect of increasing k for a forward exothermic reaction?
K decreases as temperature increases
what effect does the catalyst have on K?
catalysts don’t have an effect on the position of the equilibrium
they only affect the rate of reaction
