Equilibria and redox reactions Flashcards
What does dynamic mean?
both forward and backward reactions are occurring simultaneously
What are the features of a dynamic equilibrium?
- Forward and backward reactions are occurring at equal rates
- The concentrations of reactants and products stay constant
What is Le Chateliers principle
It states that if an external condition is changed the equilibrium will shift to oppose the change and reverse it
What is the effect of temp on equilibrium?
- temp up = shifts in endothermic (absorbs heat)
- temp down = shifts in exothermic (releases heat)
effect of pressure?
- pressure up = shifts to side with less gaseous moles
What happens if there are the same number of gaseous moles on each side?
No change in equilibrium
effect of concentration?
- conc up = shifts to reduce the conc of that substance (to use more of it up)
Effect of a catalyst?
Doesn’t effect position of equilibrium but speeds up the rate at which equilibrium is achieved?
Why don’t catalysts effect the position of equilibrium?
They speed up the forward and backward by the same amount
Haber process?
N2 + 3H2 –> 2NH3 (+ve)
- 450 degress, 200-1000 atm, Fe catalyst
Contact process?
1) S + O2 –> SO2
2) 2SO2 + 0.5 O2 –> SO3 (-ve)
- 450 degrees, 10 atm, V2O5 catalyst
Production of methanol?
CO + 2H2 –> CH3OH (-ve)
- 400 degress, 50 atm, Cr/ Zn oxides catalyst
Hydration of ethene to make ethanol?
C2H4 + H2O –> CH3CH2OH (-ve)
- 300 degrees, 70 atm, c. H3PO3 catalyst
Why are compromise temps and pressures used in industry?
- High temp = fast rate but expensive (low temp = high yield)
- High pressure = high yield and fast rate but expensive (equipment to achieve high pressures)
Why are catalysts used in industry?
Speed up rate, so lower temp can be used (cheaper) and equilibrium is effected
