Topic 7: Equilibrium
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physical system
rate of codensation= rate of evaporation= rate of melting
chemical system
rate of reaction of produts and reactants equal
features of equillibrium
• its dynamic • in a closed system • product and react CONCENTRATIOn is constant • no macroscophic changes • equillibrium can be reached from either direction
equillibrium position (Q)
proportion of reactants and products in equillibrium mixture left (in favour of reactants) right ( in favour of products)
Kc
equillibrium constant; fixed value for a particular reaction at specified temperature for which the sytem is at equillbirum - only temp affects Kc
kc formula
products/reactants
kc magnitude
shows the extent of the reaction (small Kc; in favour of reactants; large Kc; in favour of products) when kc= 1; equillibrium
reaction quotient
Q; meausure of relative amounts of reactnants and products present in a reaction at a particuarl time (substitute reaction concentration into Kc expression)
la chateliers principle
a system as equillibrium when disrupted will response in such a way to minimized the effects of change
change in conc
• increase in reactants; E shifted to right - increase in products; E shifted to left
change in pressure
only affects gaseous molecules with unequal ration of gas molecules on each side -system favours side with few gas molecules with the increase of pressure
changes in temp
• change kC value exothermic reactions; increase in temp shifts E to left to favour reactants in forward reactions (heat as product) - kc decreases endothermic reactions: increase in temp shifts right to favour products in forward reaction (heat as a reactant) - kc increases
catalyst
speeds up rate at with equillibrium is reached • increases rate equally of forward + backward reactions • doesnt affect Kc or equillibrium positions
haber process
production of ammonia: exothermic forward reaction high pressure (4:2 ratio of gaseos molecules) medium temperature of 450.c (exoterhmic reaction; need fast reaction rate but also high yield) catalyst: iron, aluminum or magneisum oxides ruthenium
contact process
combustion of sulfur to form SO2 oxidation of sulfur to form SO3 SO3 + water to produce sulfuric acid • high pressure • moderate tempreature (450C) • cataluyst; vanadium (V) oxide
methanol production
production of methanol from carbon monoxide and hydrgen (exothermic) - high pressure - low temperature (250C) Catalyst: - copper -zinc oxide -aluminium trioxide