Unit 3 Flashcards
why is it important that a reaction doesn’t happen too slow
it won’t be economically viable
why is it important that a reaction doesn’t happen too fast
an explosion could occur
why must reaction rates be controlled in industrial processes
- it won’t be economically viable
- an explosion could occur
what can collision theory be used to explain
the effect of concentration, pressure, surface area, temperature, and collision geometry
what theory can explain the effect of concentration, pressure, surface area, temperature, and collision geometry
collision theory
what does a potential energy diagram show
the energy pathway of a reaction
what can be used to show the energy pathway of a reaction
potential energy diagram
what is temperature a measure of
the average kinetic energy of the particles in a substance
what is the average kinetic energy of the particles in a substance
temperature
activation energy
the minimum kinetic energy required by colliding particles before a reaction may occur
the minimum kinetic energy required by colliding particles before a reaction may occur
activation energy
what can energy distribution diagrams be used to explain
the effect of changing temperature on the kinetic energy of particles and reaction rate
what can be used to explain the effect of changing temperature on the kinetic energy of particles and reaction rate
energy distribution graphs
what two things must happen before a successful reaction occurs
- reactants must collide with the correct geometry
AND
- posses a minimum energy
- reactants must collide with the correct geometry
AND
- posses a minimum energy
what two things must happen before a successful reaction occurs
what is temperature a measure of
the average kinetic energy of the particles in a substance
what is the average kinetic energy of the particles in a substance
temperature
activation energy
the minimum kinetic energy required by colliding particles before a reaction may occur
the minimum kinetic energy required by colliding particles before a reaction may occur
activation energy
what does an energy distribution diagram explain
why increasing the temperature increases the reaction rate
why increasing the temperature increases the reaction rate
what does an energy distribution diagram explain
reaction profiles
show the enthalpy change that occurs in a reaction and the activation energy
what shows the enthalpy change that occurs in a reaction and the activation energy
reaction profiles
enthalpy change of exothermic reaction
negative enthalpy change
enthalpy change of endothermic reaction
positive enthalpy change
what reactions have a negative enthalpy change
exothermic
what reactions have a positive enthalpy change
endothermic
activated complex
high energy, unstable arrangement of atoms.
formed at the top of the activation energy barrier
high energy, unstable arrangement of atoms.
formed at the top of the activation energy barrier
activated complex
what is formed at the top of the activation energy barrier
activated complex
when is the activated energy formed
formed at the top of the activation energy barrier
how do catalysts speed up reactions
by lowering the activation energy
how does increasing temp increase the reaction rate
there is more particles that have energy greater than or equal to the activation energy
there is more particles that have energy greater than or equal to the activation energy
how does increasing temp increase the reaction rate
enthalpy change reaction
delta H = H(products) - H(reactants)
how does increasing conc lead to increase in rate
increases the number of collisions
how does increasing pressure lead to increase in rate
increases the number of collisions
how does decreasing particle size lead to increase in rate
increases the number of collisions
how does the use of a catalyst lead to increase in rate
the activation energy decreases
what can you add to decrease the activation energy
a catalyst
what two things to consider about rates of reaction graphs
- the gradient/steepness of the graph
- where the graph ends
- the gradient/steepness of the graph
- where the graph ends
what two things to consider about rates of reaction graphs
what can the gradient of a reaction graph show
the sleeper the slope, the faster the reaction
the enthalpy change of a reaction is _____ ___ ___ ______ _______
independant of the route taken
Molar volume
Volume per mole
Volume per mole
Molar volume
Units for molar volume
L mol^-1
What is molar volume dependent on
Temperature
What two factors are important in industrial chemistry
Percentage yeild
Atom economy
Actual yeild
Amount obtained
Amount obtained
Actual yeild
Theoretical yeild
Amount obtained worth full conversion of the limiting reactant
Amount obtained worth full conversion of the limiting reactant
Theoretical yeild
Environmental considerations for industrial processes
Minimise waste
Avoiding the use or production of toxic substances
Making proteomic products that can biodegrade
Atom economy
Measure of how much of the products are useful
High atom economy = ____ waste
Less
Factors influencing industrial processes
Availability, sustainability and cost of feedstock
Opportunities for recycling
Energy requirements
Marketability of by-products
Product yeild
How to ensure a costly reactant is converted into protect
Excess or less expensive reactant is used
Raw material
Substance obtained from nature
Feedstock
A chemical which is reacted to produce other chemical products. This can be from extraction or chemical synthesis.
Chemical equilibrium involves..
2 way reactions
Reversible reaction
One they can do both forwards and backwards
The final equilibrium position is _____ whether you start work the product or reactant
The same
When will the reverse reaction begin
When products form
Eventually, the rages of forward and reverse reactions will become ____
Equal
Chemical equilibrium
Equal rates of forwards and backward reactions
Constant concentration of products and reactant
Equal rates of forwards and backward reactions
Constant concentration of products and reactant
Chemical equilibrium
Dynamic equilibrium
50% reactants and 50% products.
When can dynamic equilibrium only be achieved
In a closed system
If a reaction mixture contains less than 50% products where does the equilibrium lie
To the left
What can affect the position of equilibrium
Concentration
Pressure
Temperature
Increase or decrease in conc on equilibrium
Reaction no longer at equilibrium
Increase in reactant conc
Decrease in product conc
Equilibrium position shifts to the side of products
Equilibrium position shifts to the side of products
Increase in reactant conc
Decrease in product conc
Increase in product conc
Decrease in reactant conc
Equilibrium position shifts to the side of reactants
Equilibrium position shifts to the side of reactants
Increase in product conc
Decrease in reactant conc
What happens if temp is increased on equilibrium
Reaction will move in the direction which will reduce the temperature and cool the reactants down
Why does an increase in concentration lead to the equilibrium shifting to the right
Allows the product concentration to increase
What way does the reaction move if temperature increases
In the direction in which heat is used up
The endothermic direction
What causes..
Equilibrium shifts in the direction in which heat is used up
The endothermic direction
Increase temperature
What does the reaction do if temperature is decreased
Reaction moves in the direction which will increase the temperature and heat the reaction up
Moves in the direction that uses heat up (exothermic)
Reaction moves in the direction which will increase the temperature and heat the reaction up
Moves in the direction that uses heat up (exothermic)
Decrease in temperature
Pressure changes will only affect reactions in which…
There of atleast one gas involved
There of a volume change going from reactant to products
There of atleast one gas involved
There of a volume change going from reactant to products
Requirements for pressure affecting a reaction
Equilibrium if pressure is increased
Reaction will move in the direction they will lower the pressure
In the direction where the total gas volume is lower
Reaction will move in the direction they will lower the pressure
In the direction where the total gas volume is lower
Equilibrium of pressure increased
Equilibrium of pressure decreased
Reaction will move in the direction that will increase the pressure
In the direction where the total gas volume is higher
Reaction will move in the direction that will increase the pressure
In the direction where the total gas volume is higher
Equilibrium of pressure decreased
If pressure decreased, equilibrium would move to the side with the _______ number of moles
Highest
If pressure increases, equilibrium would move to the side with the _______ number of moles
Lowest
What does equilibrium solely depend on
Products and reactants
Catalyst affect on equilibrium
Doesn’t change position of equilibrium
What type of reaction is combustion always
Exothermic
Negative value
Enthalpy of combustion
The enthalpy change that occurs when one mole of a substance burns completely in oxygen
With all reactants and products being in their standard states
The enthalpy change that occurs when one mole of a substance burns completely in oxygen
With all reactants and products being in their standard states
Enthalpy of combustion
Balanced equation for Enthalpy of combustion
Must show 1 mole of the substance that is being burnt
Molar bond Enthalpy
The energy required to break one mole of X-Y bond
2 points about making bonds
Energy released
Exothermic -^H
Energy released
Exothermic -^H
Bonds making
Bonds breaking
Energy used
Endothermic +^H
Energy released
Exothermic -^H
Making bonds
Bond Enthalpy
Energy required to break 1 mole of a particular bond between a pair of atoms in the gaseous state
Energy required to break 1 mole of a particular bond between a pair of atoms in the gaseous state
Bond Enthalpy
What is chromatography for
To seperate components present in a mixture
To seperate components present in a mixture
Chromatography
What does chromatography seperate substances based on
Polarity
Molecular size
Y axis for chromatography
Quantity of substance
X axis for chromatograph
Retention time
