2.3.2 Rates and equilibrium

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What is the collision theory?
reactions can only occur when collisions take place between articles with sufficient amount of energy // energy to break relevant bonds// min energy is called activation energy
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What is activation energy?
min energy required which particles need to collide to start a reaction
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What will increasing conc and Pa for a gas do to collisions?
more particles per unit vol - particles collide with greater frequency and there will be a higher rate of successful collisions
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What is a catalyst?
increases reaction rate by providing an alternative route with a lower activation energy without being used up
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What are the benefits of using catalysts?
lower temps/Pa // save energy costs as reduced energy demand// fewer CO2 emissions // enable different reactions to take place // better atom economy // less waste // fewer undesired products // less hazardous products
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What types of catalysts are most commonly used and why?
enzymes // used to produce very specific products // operate effectively at RTP
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What is the economic importance of catalysts?
Fe in ammonia production // Ziegler-natta in poly(ethene) production
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What is rate of reaction?
the change in concentration of a substance per unit time
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What is the Maxwell Boltzman distribution (MBD) ?
shows the spread of energies that molecules of a gas or liquid have at a particular temp
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According to the MBD what will happen if temp increases?
distribution shift towards having more molecules with higher energies
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On a MBD what will an increase in conc do?
area under the line will increase as more particles
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On a MBD what will a catalyst do?
more particles will have Ea as it is lower
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On a MBD what will increasing surface area do?
collisions occur more frequently
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What will rate curves illustrate?
different concentrations have sam initial rate // steeper gradient = faster rate
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What is dynamic equilibrium?
forward and backward reactions occurring at equal rate
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What is Le Chatelier's Principle?
if an external condition is changed, the eqm will shift to oppose it
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What effect will an increase in temp do to eqm?
will hit towards endothermic reaction to decrease temp
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What effect will an increase in Pa do to eqm?
shift towards reaction with fewest molecules
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What effect will an increase in conc of a molecule do to eqm?
shift to decrease amount
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What effect will a catalyst have on eqm?
no effect // will speed up rate at which eqm achieved
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Why are there compromises on temp involving eqm?
low temp may give higher yield of products but slow rate // compromise for temp and yield rate
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Why are there compromises on Pa involving eqm?
high Pa may give high yield and rate // Pa expensive to produce // equipment expensive // hazardous
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What are the compromises in the Haber process?
low temp gives high yield but slow rate // high Pa good yield but expensive // catalyst used to speed up rate
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What else can be done to improve yields?
recycle unreacted reactants back into the reactor
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Card 2

Front

What is activation energy?

Back

min energy required which particles need to collide to start a reaction

Card 3

Front

What will increasing conc and Pa for a gas do to collisions?

Back

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Card 4

Front

What is a catalyst?

Back

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Card 5

Front

What are the benefits of using catalysts?

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