kinetics and equilibrium

    Cards (83)

    • What is the activation energy (EA)?
      Minimum energy needed for a reaction
    • What does the Maxwell-Boltzmann energy distribution illustrate?
      Spread of energies in gas or liquid
    • Why does the energy distribution curve go through the origin?
      No molecules have zero energy
    • Why does the energy distribution curve never meet the x-axis?
      No maximum energy for molecules exists
    • Where is the mean energy of particles located on the curve?
      Not at the peak of the curve
    • What does the area under the Maxwell-Boltzmann curve represent?
      Total number of particles present
    • Why do a few particles have low energies?
      Collisions cause some particles to slow down
    • How can a reaction go to completion if few particles exceed EA?
      Particles can gain energy through collisions
    • What does Emp represent in the energy distribution?
      Most probable energy of particles
    • What happens to the energy distribution as temperature increases?
      More molecules have higher energies
    • What remains constant as temperature increases?
      Total area under the curve
    • How does the range of energies change with temperature?
      Wider range of energies at higher temperatures
    • What happens to Emp and mean energy at higher temperatures?
      Both shift to higher energy values
    • What is the rate of reaction defined as?
      Change in concentration over time
    • How is the rate of reaction determined from a concentration vs. time graph?
      Gradient of the curve indicates rate
    • What is the initial rate of reaction?
      Rate at the start of the reaction
    • How can reaction rates be calculated from graphs?
      By drawing a tangent and calculating gradient
    • What effect does increasing concentration have on particle collisions?
      Increases frequency of effective collisions
    • How does the shape of energy distribution curves change with concentration?
      Curves become higher, area increases
    • What happens to the number of molecules with energy > EA when concentration increases?
      More molecules exceed activation energy
    • What state do all reversible reactions reach?
      Dynamic equilibrium state
    • How do different volumes of the same initial concentrations affect reaction rates?
      Same initial rate, different final amounts
    • What is the general reaction for the formation of ammonia?
      N2 + 3H22NH3
    • What are the two features of dynamic equilibrium?
      1. Forward and backward reactions occur at equal rates.
      2. Concentrations of reactants and products remain constant.
    • What factors increase the rate of reaction?
      Higher concentration, temperature, surface area
    • What does the term 'position of equilibrium' refer to?
      Composition of the equilibrium mixture
    • How is the reaction rate measured in the sodium thiosulfate and hydrochloric acid experiment?
      As 1/time for cross disappearance
    • What happens if the position of equilibrium favors the reactants?
      Equilibrium mixture contains mostly reactants
    • Why is measuring 1/time an approximation for reaction rate?
      It does not include concentration changes
    • What does Le Chatelier’s principle state?
      • If an external condition changes, equilibrium shifts to oppose the change.
      • It tries to reverse the effect of the change.
    • How does increasing temperature affect equilibrium?
      Shifts to endothermic direction to absorb heat
    • What happens when concentration is doubled?
      Double the number of particles per volume
    • What is the effect of increasing temperature on ammonia yield?
      Lower yield of ammonia
    • How does increasing surface area affect reaction rates?
      Increases frequency of successful collisions
    • What happens if temperature is decreased in a reaction?
      Equilibrium shifts to exothermic direction
    • What is the definition of a catalyst?
      Increases reaction rates without being used
    • What is the trade-off with low temperatures in reactions?
      Higher yield but slower reaction rates
    • How does increasing pressure affect equilibrium?
      • Shifts towards side with fewer moles of gas.
      • Reduces pressure by opposing the change.
    • How do catalysts increase reaction rates?
      By providing an alternative route with lower EA
    • What is the effect of increasing pressure on methanol yield?
      Higher yield of methanol
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