Chapter 10 Flashcards
What is a reversible reaction?
A reaction that goes both ways
As the reactants get used up, what happens to the forward reaction?
It slows down
As more of the product is formed, what happens to the reverse reaction?
It speeds up`
What is a dynamic equilibrium?
When the forward reaction will be going at the same rate as the backward reaction, so the amounts of reactants and products will not be changing
At an equilibrium, what happens to the concentration of the reactants and products?
The concentrations stay constant
What is a closed system?
When nothing can get in or out
What is the only system that a dynamic equilibrium can be achieved in?
A closed system
What is the symbol of the equilibrium constant?
Kc
What does the equilibrium constant give you an idea of?
How far left or right the equilibrium is.
What is a homogeneous system?
A system in which everything is in the same state
For a general reaction, aA +bB —> dD + eE, what is the equilibrium constant?
K=(D)^d x (E)^e / (A)^a x (B)^b
In the formula of the equilibrium constant, what do the lower case letters represent?
The number of moles in each substance
In the formula of the equilibrium constant, what do the upper case letters represent?
The concentration in moldm^-3
What is a heterogeneous system?
A system where not everything’s in the same state
When calculating the equilibrium constant of a heterogeneous system, what don’t you include in the calculation?
Solids or pure liquids, as their concentration stay constant throughout the reaction
Why don’t you include catalysts in expressions for the equilibrium constant?
Because catalysts don’t affect the equilibrium concentrations of the products or reactants
What can you use to achieve a dynamic equilibrium quicker?
A catalyst
What does le chatelier’s principle predict?
What will happen if conditions are changed
If you move the position of the equilibrium to the left, what will you get more of?
The reactants
If the position of the equilibrium moves to the right, what will you get more of?
The products
If there’s a change in the concentration, pressure or temperature, what will happen to the position of the equilibrium?
It will change
If you increase the concentration of the reactant, what does the equilibrium do?
It tries to get rid of the extra reactant, so it makes more product, so the equilibrium is shifted to the right
What state does increasing the state only affect?
Gases
What does increasing the pressure do to the position of the equilibrium?
It shifts the equilibrium to the side with fewer gas molecules, in order to reduce the pressure
What does increasing the temperature of a reaction do to the position of the equilibrium?
It shifts it in the endothermic reaction
What does decreasing the temperature of a reaction do to the position of the equilibrium?
It shifts it in the endothermic direction
In an industrial process, what balance has to be achiveved?
A balance between high rate and high yield
What can ethanol be formed from?
Ethene and steam
Is the forward reaction of the production of ethanol a endothermic or exothermic reaction?
It is an exothermic reaction
What pressure and temperature is ethanol formed at?
60-70 atmospheres and 300C
Despite the forward reaction of ethanol being exothermic, what is the negative consequence of low temperatures?
A slower rate of reaction
Why do you use a fairly high pressure in the production of ethanol?
Because it favours the forward reaction
