Unit 1: Section 6: Equilibria and Redox Reactions Flashcards
Explain how dynamic equilibrium happens
The forward reaction slows down as the reatants get used up and more products are formed and the backwards reaction speeds up
After a while, the forward and backward reaction happens at the same time
What is dynamic equilibrium
When the forward reaction is happening at the same rate and time as the backwards reaction
What is a condition in order for dynamic equilibrium to happen
The reaction has to happen in a closed system
What is Le Chatelier’s principle
If a reaction at equilibrium is subjected to a change in concentration, pressure or temperature, the position of equilibrium will move to counteract the change
If a reaction is at equilibrium and you increase the concentration of the reactants what will happen
The equilibrium will act to get rid of the extra reactant by making more product
If a reaction is at equilibrium and you increase the pressure of the reactants what will happen
Changin pressure only affects equilibria involving gases
Increasing pressure shifts equilibrium to the side with the fewer gas molecules
If a reaction is at equilibrium and you increase the temperature of the reactants what will happen
The equilibrium shifts in the endothermic direction to absorb this heat
Explain the experiment you can do to follow equilibrium shifts
The reaction of [Cu(H20)6]^2+ with concentrated HCl
The ion reacts with the solution of HCl to form a copper chloride complex - [CuCl4]^2-
This reaction is reversible - at any point there will be any of the two solutions present
[Cu(H20)6]^2+ is light blue and [CuCl4]^2- is green/yellow
You can use the colour change to monitor the position of the equilibrium
What is Kc
Equilibrium constant
It is the ratio of the concentrations of the products and reactants after equilibrium is reached
What is the formula for Kc
aA + bB ⇌ dD + eE (The lower case letters are just the number of moles of each substance in the equation)
Kc = ([D]^d [E]^e)/([A]^a [B]^b)
How do you find the units of Kc
Substitute the units in the formula instead of the contentration
What units does the volume have to be in order to work out the molar concentration of a substance
dm^3
What is the relationship between the change in product and the Kc
If the product increases then the Kc increases
If the product decreases then the Kc decreases
What happens with regards to the Kc if the concentration of one of the substances in the reaction changes
The concentrations of the other substances will change to keep the value of Kc the same
What does adding a catalyst do the Kc
Nothing
The catalyst increases the forward and backward reaction at the same rate
What is oxidation
Loss of electrons
What is reduction
Gain of electrons
What do oxidising and reducing agents do
Donate and recieve electrons to be oxidised and reduced
What is the oxidation state
The oxidation state of an element tells you the total number of electrons it has donated or accepted
What is the oxidation state of uncombined elements
Oxidation state of 0
What is the oxidation state of elements that have just bonded to identical atoms
Oxidation state of 0
What is the oxidation state of a simple monatomic ion
The same as it’s charge
In a compound ion which ion will have the negative oxidation state
The most electronegative element
What is the oxidation state of neutral compounds
Oxidation state of 0
What is the oxidation state of oxygen
It usually has an oxidation state of -1
What is the oxidation state of hydrogen
It usually has an oxidation state of 0
How can oxidation states be shown using systematic names
Roman numerals
What do you have to do in order to combine two ionic half equations
Multiply the electrons in the each equation so that there are the same electrons in each equation and just combine them and then cancel out the electrons
What do you do if on one side of the half equation you have oxygen atoms and one side you don’t
Add H20 to the side with no oxygen atoms and add H+ ions to the other side to balance the equation
