Rates of Reaction - C8 Flashcards
What is the equation for rate of reaction
= Amount of reactant used or product formed / Time
What units are used for rate of reaction
g/s and cm3/s
What is rate of reaction
It is a measure of the change in a reaction per unit time
How do you measure the rate at a certain point of a graph
You draw a tangent off that point
What is activation energy
It is the minimum amount of energy the particles need to react together
How can rate of reaction be increased
Increasing the frequency of collisions
Increasing the energy of collisions
Lowering the activation energy
What factors affect rate of reaction
Temperature
Catalyst
Surface Area
Concentration
Why does temperature affect rate of reaction
It gives particles more energy causing them to go faster
This causes more frequent collisions
Collisions have more energy
What is concentration
A measure of the number of particles of a substance in a certain volume
Why does concentration affect rate of reaction
More particles, so more frequent collisions
What is a catalyst
It is a substance that speeds up chemical reactions without being used up
This works by providing an alternative reaction pathway which has a lower activation energy
Why does catalysts affect the rate of reaction
Because it lowers the activation energy for the reaction
This means that particles can react even with moderate amounts of energy
Why does Surface Area affect rate of reaction
More reactant is exposed so more frequent collisions
What method can you use for surface area
Loss in mass method
What method can you use for temperature
The cross at the bottom of the flask method
What method can you use for concentration
Gas syringe method
What is a reversible reaction
It is a reaction which once completed can react backwards to form the original reactants
If the forward reaction is endothermic, what is the reverse reaction
exothermic
What is a salt
A compound formed when hydrogen is replaced by a metal
What is water of crystallsation
It is water molecules contained in crystalline lattice
What is a hydrated salt
It is a salt with water of crystalline
What is a anhydrous salt
It is a salt where water of crystalline is not present
What is dynamic equilibrium
It is when the rate of the forward reaction is the same as the rate of the backward reaction in a closed system
What is Le Chatelier’s Principle
That when a change in condition is introduced to a system at equilibrium, the position of the equilibrium shifts to cancel out the change
How does changing the concentration in equilibrium effect the equilibrium
When a substance is added to the left hand side, the equilibrium shifts to the right
How does changing the temperature in equilibrium effect the equilibrium
When the temperature is increased the equilibrium shifts to the side that the endothermic reaction is going
When the temperature is decreased the equilibrium shifts to the side that the exothermic reaction is going
How does changing the pressure in equilibrium effect the equilibrium
When the pressure is increased the equilibrium shifts to the side with less moles
When the pressure is decreased the equilibrium shifts to the side with more moles
What is the Haber process
It is the process of making ammonia from nitrogen and hydrogen
The forward reaction is exothermic
Where does the nitrogen come from for the Haber process
It comes from the air and is separated
Where does the hydrogen come from for the Haber process
It comes from methane or other natural gases
How does the Haber process work
- Gas containing hydrogen and nitrogen is compressed to a pressure of 200 atm and heated to 450 degrees - This is to increase the rate of reaction
- The mixture then goes into the reaction vessel containing a iron catalyst where an equilibrium is formed - This is to increase the rate
- The mixture is then cooled and the Ammonia liquefies and is separated
- Unreacted nitrogen and hydrogen and fed back into the system
What conditions is the Haber process carried out in
High Pressure - Increase the rate of reaction and shift the equilibrium to the right
Quite High Temperature - Increases the rate of reaction but shifts the equilibrium to the left which reduces the yield
