Topic 10 Chemical Equilibruim Flashcards
what is a reversible reaction
reaction that can go in forward & backward direction
what is dynamic equilibruim
occurs when forward & backward reaction occur at equal rates and the the concentration of products & reactants are constant
what are the 2 conditions needed for dynmanic equilibruim
- must be reversible
- Must be in closed container
what is Le Chatelier’s principle
States that if an external condition is changed, the equilibrium will shift to oppose the change and try to reverse it.
what is the only case when Le Chatelier’s principle can be applied
This only works in homogeneous equilibrium, which is when reactants and products are in the same state.
how does change in concentration effect position of equilibruim & why
If we increase the concentration of a reactant or product, the equilibrium will shift to reduce it.
If we decrease the concentration of product or reactant, the equilibrium will shift to try to increase it.
how does change in pressure effect position of equilibruim & why
If we increase pressure, the equilibrium will shift to the site with fewer numbers of particles to reduce the pressure.
If we decrease pressure, the equilibrium shifts to the side with a greater number of particles to increase pressure.
how do you know if the forward reaction is exothermic or endothermic
If enthalpy change of the forward reaction is negative, the forward reaction is exothermic. If enthalpy change is positive, the forward reaction is endothermic.
how does change in temperature effect the position of equilibruim and why
If we increase temperature equilibrium will shift to. Oppose this by moving to endothermic direction to try and reduce temperature by absorbing heat.
If we reduce temperature, equilibrium shifts to oppose by moving to exothermic direction to try to increase heat by giving it out.
what effect do catalyst have on position of equilibruim & why
Catalysts have no effect on position of equilibrium as a catalyst will speed up rate of forward and backward reaction equally. Catalyst speeds up the row which equilibrium is reached but have no effect on the yield.
what are the normal conditions in the ethanol reaction
- Pressure : 60 Atmospheres
- Temperature : 300 degrees c
- Catalyst : Phosphuric acid (H3PO4)
how will changing temperature effect postion of equilibruim in the ethanol reaction
Since forward reaction is exothermic, so decreasing the temperature will favour the endothermic side, so equilibrium shifts to right to produce more ethanol.
why do we still keep temperature high despite higher temperature favouring ethanol production
Lower temperature means lower rate of reaction, so 300°C is a compromise between yield / rate.
how will change in pressure effect change in position of equilibruim in ethanol reaction
Higher pressure means equilibrium will move to right to produce more arsenal. Higher pressure also increases rate of reaction, so it’s a win-win situation.
why do we still keep a lower pressur despite a higher one resulting in more yield & speed of ethanol
High pressure environments are expensive due to more robust and thicker pipes being needed. There is a compromise between yield & speed /cost
