3.1.6 equilibria Flashcards
what does completion mean?
they continue until all the reactants are used up, then the reaction stops
What are the reactions called that do not go to completion?
reversible reactions
what is the chemical equilibrium reached?
A chemical equilibrium is reached in a reversible reaction with the rate of the forward reaction is equal to the rate of the reverse reaction
What is dynamic equilibrium?
rate of the forwards and backwards reactions are equal and the concentration remains constant
what can chemical equilibria either be?
homogeneous or heterogeneous
what are characteristics of a dynamic equilibrium?
- A dynamic equilibrium can only occur in a closed system
- reactions continue to occur - the reaction is dynamic
- The concentrations of reactants and products remain constant
- The equilibrium can be established from either side of the reaction
what is a closed system?
No more reactants are added, and no reactants are removed
as the pressure of the system is constant
what are the three factors that affect the position of an equilibrium?
Temperature, pressure and concentration
what does Le Chatelier’s principle state?
A system at equilibrium will shift to oppose any change imposed upon it
Is the position of a chemical equilibrium affected by a catalyst?
why?
No
catalysts speed up the forwards and backwards reactions equally
If the concentration of one of the reactants is increased, what will happen to the equilibrium?
The position of the equilibrium will shift to oppose the change
pressure only affects the position of chemical equilibria that involve what?
Gases
if the pressure is increased equilibrium that the position of the equilibrium moves, where?
To the sides of the reaction with fewer gaseous moles
as this reduces the pressure of the gaseous system
where the temperature of a reaction is increased, what reaction is favoured, and why?
The endothermic reaction is favoured
As this remove the added heat also opposes the increase in temperature
where the temperature of reaction is decreased, what reaction is favoured? why?
The exothermic reaction is favoured
As this releases, heat, energy and opposes the decrease in temperature
what are the optimum conditions for the Haber process?
- The forward reaction, producing ammonia is exothermic, answer releases, heat, energy
- Applying Le Chatelier’s principle, this is favoured by lower temperatures as this will shift the equilibrium to the right and increase the yield of ammonia at equilibrium
what temperatures and pressures are the best yields obtained at?
very low temperatures and very high pressures
at …….. temperatures, the reaction rate is …….. and although the ………. of product is better, the rate of …………. is too slow to be ……… …………….
low
slow
yield
production
cost effective
what conditions do industrial chemists use that produce an acceptable yield an acceptable rate?
compromise conditions
what are two important chemicals that are increasingly finding use as fuels?
ethanol and methanol
what’s the chemical formula for ethanol?
C2H5OH
ethanol is prepared by the hydration of what?
Ethene
what is Kc?
A ratio of the concentration of the products to reactants at equilibrium
does the left side or right side of an equation go on the top when writing Kc values?
right
