irreversible reactions
reactions in which reactants cvrt to prods but prods cannot cvrt back to reactants
reversible reactions
reactions which proceed in both forward and backwards directions
dynamic equilibrium
no net change in concentrations of reactants and products, mixture of recatants and products said to be at dynamic eqlm. It is the state of reversible process in a closed system which rate of forward = rate of backwards reactions, but not equal to 0.
what is a close system and does a reversible reaction complete here
only free transfer of energy, no completion as as soon as reactants form products, products decompose back into reactants
what is a open system and does a reversible reaction complete here
free transfer of energy and matter, reversible reaction can go into completion as reactants/products are removed from the system
state eqlm law, Kc expression
for a reversible reaction at eqlm, ratio of the product of concentrations of products to the product of concentrations of reactants, each raised to a power equal to its coefficient in the chemical equation.
state the effect of temp, change in conc of reactants/products on Kc
temperature dependent, no change
state the effect of temp, as well as changes in partial pressure of reactants and products on Kc
temp-dependent, no change
at a given temp, what is the relationship between partial pressure of gas and its concentration
directly proportional
le chatelier’s principle
if a system at dynamic eqlm is subjected to a change which disrupts the eqlm, position of eqlm will hift to counteract effect of change to establish new eqlm
how does p.o.c shift with increase/decrease in concentration
shift opposite (foward/backward) to decrease/increase concentration
effect of increasing total pressure of system by decreasing volume
p.o.c shift to decrease pressure, by reducing amount of gaseous particles, p.o.c shift left/right.
partial pressures of all gaseous particles increase, rate of <favoured> reaction increases more than other one, due to more reactants than products</favoured>
what happens when an inert gas is added constant volume
increase in total pressure of, due ot increase in amt of gaseous particles at a constant volume, but partial pressure of each gas component remains unchanged, p.o.c does not shift (no effect on forward/backward)
what happens when partial pressures of gaseous component is increased/decrease
p.o.c will shift to decrease/increase partial pressure of gaseous component
what happens when an inert gas is added constant pressure
increase in total volume, partial pressure of all gaseous components decrease, p.o.c shift to increase no. of moles of gaseous particles, rate of forward and backward reaction decrease
what must be known in determining effect of temp change and how does p.o.c change with increase in temperature
state effect on forward and backward reactions as well as kp, kc
standard enthalpy change of reaction, position of eqlm shifts to decrease temperature of system, favour endothermic reaction that absorbs heat
forward backward increase with increased temp, but rate of reaction for endothermic reaction increases by greater extent
kp/kc will increase if more products are formed (fwd reaction favoured) and change in temp (increases)
effect of ctaalyst on position of eqlm and rates of reactions (foward and backward)
no change in p.o.c, increases forward and backward reaction by same extent by providing alternative pathway for reaction to occur at lower activation energy
conditions used in haber process
450 temp, about 250 atm, finely divided iron catalyst with alumnium oxide, with Al2O3 and potassium oxide as promoters for the iron catalyst
explain why relatively high temp of 450 is used
forward reaction exothermic, lower temp favour higher yield of ammonia but reacting particles need sufficient energy for effective collisions to form ammonia so moderately high temperature needed to have sufficient energy
explain why high pressures are avoided
high pressure favour forward reaction produce more ammonia, due to mole ratio 4:2, but cost of production increase since equipment need to withstand high temperature, thus carried out at mod pressure of 200-250 atm.
