Unit 6 Flashcards
Entropy
Measure of the distribution of total available
energy between particles in a system
More disorder =
Entropy increasing
Equilibrium state ( during a reaction )
Equilibrium is dynamic. At equilibrium state the rate of the forward reaction is equal to the rate of the backward reaction.
Reaction takes place at teh same rate as its reverse reaction, so no net change is observed
What does equilibrium is dynamic mean
Just because no change is visible it does nit mean the reaction has stopped . The reaction hasn’t stopped but both forward and backward reactions are still occurring
What does equilibrium is achieved i a closed system mean
A closed system prevents exchange of matter with the surroundings, so equilibrium is achieved where both reactants and products can react and recombine with each other.
What - The concentrations of reactants and products remain constant at equilibrium
The concentrations of reactants and products remain constant at equilibrium
At equilibrium there is no change in what type of properties ( what does this mean ? )
At equilibrium there’s no change in macroscopic properties (This refers to observable properties such as colour and density. These don’t change as they depend on the concentrations of the components of the mixture.)
Two features of dynamic equilibrium
- Forward and backward reactions are occurring at
equal rates. - The concentrations of reactants and products stay constant
Effect of temprature on equilibrium ( increased ‘
If temp is increased the equilibrium will shift to oppose this and move to the side of the endothermic reaction by absorbing heat ( normally endothermic reaction is becjawrds )
Temp on equilibrium ( decreased )
Move to the exothermic side to try and increase teh temperature by giving out heat
Effect of increasing pressure on equilibrium
Increasing pressure will cause the equilibrium to shift towards the side with fewer moles of gas to oppose the change and thereby reduce the pressure.
Why not very low tempratures for yield
Low temperatures may give a higher yield of product but will also result in slow rates of reaction. Often a compromise temperature is used that gives a reasonable yield and rate.
Why not super high pressure ?
Increasing pressure may give a higher yield of product and will produce a faster rate. Industrially high pressures are expensive to produce ( high electrical energy costs for pumping the gases to make a high pressure) and the equipment is expensive (to contain the high pressures)
Amount of product used ( formula )
Rate of reaction * time taken
Why is cotton wool sometimes placed on flasks taht have gases as products
Cotton wool is usually placed in the mouth of the flask which allows gas out ( so taht loss of mass can be measured ) but prevents any materials from being ejected from the flask (if the reaction is vigorous)
