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chemistry 🧪 > kinetics > Flashcards

kinetics Flashcards

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1
Q

what are the 4 conditions for a chemical reaction? (kinetics)

A
  • collisions
  • collisions where the energy that they collide with is higher than the activation energy
  • successful conditions
  • energy is bigger than the activation energy & has the correct orientation
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2
Q

what are the 5 factors that affect the rate of reaction? (kinetics)

A
  • temperature
  • concentration
  • pressure
  • surface area
  • catalysts
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3
Q

how does temperature affect the rate of reaction? (kinetics)

A
  • increasing the temperature increases the speed of the molecules
  • this increases both their energy & the number of collisions
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4
Q

how does concentration affect the rate of reaction? (kinetics)

A
  • increasing the concentration of a solution causes there to be more particles
  • if there are more particles present in a given volume then collisions are more likely
  • this increases the rate of reaction
  • however as a reaction proceeds the reactants are used & their concentrations fall
  • in most reactions the rate of reaction drops as it continues to
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5
Q

hows does pressure affect the rate of reaction? (kinetics)

A
  • increasing the pressure of a gas reaction has the same effect as increasing the concentration of a solution
  • there are more molecules/atoms in a given volume therefore collisions are more likely
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6
Q

how does surface area affect the rate of reaction? (kinetics)

A
  • increasing the surface area of solid reactants means that the greater the total surface area of a solid, the more of its particles are available to collide with molecules in a gas or liquid
  • this means that breaking a solid lump into smaller pieces increases the rate of reaction as there are more sites for reaction
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7
Q

how do catalysts affect the rate of reaction? (kinetics)

A
  • catalysts are substances that can change the rate of reaction without chemically changing themselves
  • they are not used up in the reaction
  • they lower the activation energy by providing an alternative pathway that requires less energy
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8
Q

how do you calculate the mean rate of reaction? (kinetics)

A
  • quantity of products ÷ time taken
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9
Q

how do you calculate the mean time taken? (kinetics)

A
  • quantity of products made ÷time taken
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10
Q

define activation energy (kinetics)

A
  • the minimum energy needed to start a reaction
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11
Q

what is an exothermic reaction? (kinetics)

A
  • reaction where the reactants have more energy than the products
  • release energy into the environment
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12
Q

draw the enthalpy diagram for an exothermic reaction (kinetics)

A
  • refer to folder
  • reactants should have more energy than the products
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13
Q

what are exothermic reactions? (kinetics)

A
  • reactions where the products have more energy than the reactants
  • takes energy in from the environment
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14
Q

draw the reaction profile for an endothermic reaction (kinetics)

A
  • refer to folder
  • product should have more energy than the reactants
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15
Q

define transition state (kinetics)

A
  • the line at the top of the curve in an enthalpy diagram
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16
Q

what happens during the transition state? (kinetics)

A
  • some bonds are in the process of being made
  • some bonds are in the process of being broken
  • it has extra energy & is unstable
17
Q

what does the Maxwell-Boltzmann distribution tell us about? (kinetics)

A
  • the distribution of energy amongst particles
18
Q

draw the Maxwell-Boltzmann distribution graph (kinetics)

A
  • no. of molecules on your axis
  • kinetic energy on x axis
  • graph peaks to the left & levels off close to zero on the right
19
Q

what happens to the Maxwell-Boltzmann distribution graph at higher temperatures? (kinetics)

A
  • the peak of the curve is lower & moves to the right
  • the number of particles with very high energy increases
  • the total area under the curve is the same for each temperature because it represents the total number of particles
20
Q

what does the shaded area of the Maxwell-Boltzmann distribution graph represent? (kinetics)

A
  • the number of molecules that have greater energy than Ea at each temperature
21
Q

what does the Maxwell-Boltzmann distribution graph show about higher temperatures? (kinetics)

A
  • shows that at higher temperatures more of the molecules have greater energy than Ea, so a higher percentage of collisions will result in reaction
  • this is why reaction rates increase with temperature
  • a small increase in temperature produces a large increase in the number of particles with energy greater than the activation energy
22
Q

do concentration & pressure affect the Maxwell-Boltzmann distribution? (kinetics)

A
  • no
  • increased number of molecules makes collisions more likely anyway
23
Q

what type of energy does new bonds being created provide? (kinetics)

A
  • new bonds being creates will provide more kinetic energy to the system
  • this fuels further successful collisions
24
Q

what do catalysts provide? (kinetics)

A
  • catalysts provide an alternative reaction route with a lower activation energy
  • they do not impact the distribution

chemistry 🧪 (12 decks)

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