3.1.5: Kinetics Flashcards

1
Q

What is a rate of reaction and how is it calculated?

A

how quickly something changes
(reactants -> products)

rate of reaction= (reactants used or product produced)/ time

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2
Q

What is collision theory?

A
  • in order for atoms to bond, they must collide in the correct orientation with sufficient energy (energy to overcome atom repulsion)
  • there needs to be enough energy to overcome atom repulsom
  • when bonds break, molecules to deform to rearrange atoms

increasing temperature, increases energy (kinetic)

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3
Q

How do you put Relative reaction Rates on a graph?

A

volume × concentration= where y axis ends
molecule size/ temperature= steepness of the line/ how steep

this is because the larger s.a. of the molecule and higher temperature, the faster the rate of reaction.

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4
Q

What is activation energy?

A

the minimum energy required for a reaction to take place (Ea)

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5
Q

What’s an endothermic and exothermic reaction?

A

Exothermic (-△H)- energy is released in making bonds (more energy in reactants than products)
Endothermic (+△H)- energy is absorbed in breaking bonds (less energy in reactants than products)

BENDy MEXican

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6
Q

What do you annotate on an exothermic and endothermic graph?

A
  • reactants
  • products
  • overall energy change (△H)
  • activation energy (Ea)
  • transition state
  • x= time/ reaction progress
  • y= energy
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7
Q

What is the highest point on a endothermic/ exothermic graph?

A

transition state/ active complex
A+B-C–>A-B+C
- reactions occur as when 2 particles approach and the repulsion between atoms causes an increase in potential energy
- all 3 atoms (A,B and C) join by partial bonds and as bond AB forms, BC breaks and potential energy forms

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8
Q

What is a rate of Reaction?

A

How quickly a reaction takes place

rate of reaction= reactants used (or product produced)÷ time

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9
Q

What are the different methods to test for rates of reaction?

A
  • collecting gas in a syringe (reduction/ gain oxygen)
  • measure change in mass
  • pH tracker
  • measure concentration change
  • measure precipitate formed

÷ time

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10
Q

What factors affect rates of reaction?

A
  • concentration
  • pressure
  • surface area
  • temperature
  • catalyst
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11
Q

How does concentration affect a rate of reaction?

A
  • there is more particles in the same volume (or the reactant than the water)
  • more frequent collisions
  • however, as the reactants get used up in a reaction, the concentration drops slowing down the rate
  • this increases the rate of reaction
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12
Q

How does pressure affect a rate of reaction?

gases only

A
  • gas particles are compressed into smaller volume
  • more frequent collisions
  • this increases the rate of reaction
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13
Q

How does surface area affect a rate of reaction?

A
  • more particles exposed at the surface
  • so there’s more space for collision to occur between the reactants
  • more frequent successful collisions
  • this increases the rate of reaction
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14
Q

How does temperature affect a rate of reaction?

A
  • particles gain more kinetic energy
  • particles move faster so there’s more frequent collisions
  • collide with more energy to meet Ea (with frequency and speed)
  • this increases the rate of reaction
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15
Q

How does the presence of a catalyst affect a rate of reaction?

A
  • creates an alternative reaction pathway
  • lowers activation energy
  • more particles can react with the same energy (small amount)
  • this increases the rate of reaction without getting used up
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16
Q

What is the maxwell-boltzman distribution?

A
  • ## shows how speed/ energies of moving molecules vary at different temperatures
17
Q

What is the maxwell-boltzman curve?

A
  • no molecules with 0 energy
  • few molecules with high energy
  • lower temp.- higher curve, towards left, ends earlier approaching asymptope
  • area under graph always the same for each curve though diff. temperatures
  • as temp. increases, so does probability of molecules that meet Ea
  • adding catalyst lowers Ea
    x axis- energy E

y axis- fraction particles with energy E

18
Q

How do you draw a maxwell-boltzman curve?

A
  • increasing temp. makes molecules on average have more kinetic energy and move faster
  • so more molecules have energies greater than Ea
  • as molecules have more ke, they collide more frequently
  • temperature increasing also increases frequency and energy of molecules
  • this increases rate of reaction