C8 rate and equilibrium

Created by

Lissy

Cards (31)

What are the 2 ways to calculate rate of reaction
1-measure the amount of one of the products that is formed - when a gas is formed and collected in a gas syringe
2-measure the amount of the reactant used up over time by putting the reaction on the scale and checking the mass
What are the 2 rate of reaction equations
Mean rate of reaction= quantity of reactant used/time
Mean rate of reaction= quantity of product formed/time
If a product is solid how will it be measured and what is the unit for rate
Measured in grams
Unit for rate g/s
If reactant/products is a liquid or solution how will it be measured and what is the unit for rate
Measured in $cm^3$
Unit for rat3 $cm^3$ /s
What is the collision theory
States that for a sucessful chemical reaction to happen
particles must collide in order to react
the particles must have enough energy when they collide for a collision to be successful
the minimum amount of energy needed is called activation energy
What conditions change the frequency of collisions
Temperature, concentration, pressure and surface area
What will the reaction on a head on collision be
More energetic
Has activation energy
Reaction takes place
what will the reaction energy on a glancing blow be
Less energetic
No reaction
No activation energy
what is termperature
The average kinetic energy of the particles
What happens if the temperature of a substance increases
Kinetic energy increases
Particles will move faster
There will be more frequent collisions and the collisions will have more energy
There will be more frequent successful collisions
The rate of reaction will increase
What is the concentration of a solution
A measure of the number of solute particles dissolved in a given volume of a solution
How can you increase and decrease concentration
Increase= add more solute
Decrease= add more solvent
What happenes if you increase the concentration of a solution/pressure of gas
There will be more reactant particles in a given volume
there will be more frequent collisions between the reactant particles
there will be more frequent successful collisions
the rate of reaction will increase
What is the formula linking solvent solute and solution
Solute dissolves in the solvent to form a solution
What is a catalyst
A substance that speeds up a rate of reaction
Reduces the amount of activation energy needed
is not used up in a reaction so can be used again
often using transition metals
in form of pellets powders of gauzes
What do catalysts NOT do
Increase frequency of collisions
make collisions more energetic
What DO catalyst do
Provide an alternative reaction pathway
Lower activation energy
Higher proportion of reacting particles have enough energy to react
More frequent successful collisions
Advantages of catalysts
Cheaper to pay for a precious metal catalyst then to pay for extra energy needed without one
Avoids burning fossil fuels and conserves non-renewable resources
Stops carbon dioxide entering atmosphere
A tiny catalyst can be used over and over again
Disadvantages of catalyst
Made of very expensive precious metals (gold, platinum, palladium)
Catalysts in chemical plants eventually become poisoned and don’t work
what is a reversible reaction
Where the products react together to produce the original reactants
A+B ⇌ C+D
The reaction where A+B=C+D is the forwards reaction
The reaction where C+D=A+B is the backwards reaction
What is the ammonium chloride reversible reaction
The forward reaction is thermal decomposition (where the compound breaks down when heated)
What type of reactions are forward and backwards reactions
Forward= exothermic
Backwards= endothermic
What is an irreversible reaction
→
new compound is made
What is a closed system
Where products cannot escape or be gained
What makes something an equilibrium
At macroscopic level nothing appears to be happening but at microscopic level particles are in constant motion
What is A dynamic equilibrium
a closed system where particles are in constant motion and cannot escape
When does a dynamic equilibrium exist in a closed system
when the rate of forward reaction is equal to the rate of the reverse reaction
When concentrations of the reactants and products remain unchanged
Dynamic equilibrium example
The rate at which $CO_2$ leaved the water is equal to the rate which $CO_2$ enters the water
The concentration of $CO_2$ in the air and in the water is not changing
What is an equilibrium
microscopic particles moving in a constant motion
Always gas or aqueous
no change in reactants or products
What is le chateliers principle
If a dynamic equilibriums system is disturbed by a change in temp, pressure or concentration of one component the position of the equilibrium will shift in order to oppose the effect of this change so the dynamic equilibrium is main

The shift will either be to the right (forward reaction favoured) or left (backwards reaction favoured) whichever helps to oppose the applied change
How can the position of an equilibrium be changed
Concentration of reactants or products
Temp
pressure