Kinetics: Reaction Rates Flashcards

1
Q

What is the definition of the rate of reaction?

A
  • The change of concentration of reactant/product over time
  • The measure of the amount of product formed or reactant used over time
  • The units of rate of reaction may be given as g/s, cm3 / s or mol/s
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2
Q

What factors will increase the rate of reaction?

A
  • Increase in temperature
  • Increase in concentration of reactants
  • Increase in pressure of gaseous reactants
  • Increase in surface area of solid reactants
  • Adding a catalyst
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3
Q

What is the effect of temperature on the rate of reaction?

A
  • At higher temperatures, the particles are moving faster, so the collision frequency increases
  • Increased movement of the molecules means collisions will occur more often and with greater energy
  • Increased temperature increases rate of reaction
  • Increases collision frequency
  • Increases proportion of successful collisions
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4
Q

What is the effect of concentration of reactants on the rate of reaction?

A
  • When the concentration of a sample is increased, more molecules of substance occur in the same volume meaning they are packed closer together
  • This increases collision frequency
  • Increased concentration increases rate of reaction
  • Increases collision frequency
  • Speed of particles are the same so the proportion of successful collisions remains the same
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5
Q

What is the effect of pressure of gaseous reactants on the rate of reaction?

A
  • When pressure is increased, the gas particles occur in a smaller volume - packed closer together
  • This increases collision frequency
  • Increased pressure increases rate of reaction
  • Increases collision frequency
  • Speed of particles are the same so the proportion of successful collisions remains the same
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6
Q

What is the effect of surface area of solid reactant on the rate of reaction?

A
  • Increasing the surface area of a solid reactant means a greater surface exposed for collisions
  • This means the collision frequency increases, as such there are more successful collisions
  • Therefore a faster rate of reaction
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7
Q

What is the effect of adding a catalyst on the rate of reaction?

A
  • A catalyst is a substance that increases the rate of a chemical reaction without being changed in chemical composition or amount
  • Catalysts work by providing an alternative reaction route of lower activation energy
  • Increases rate of reaction
  • More particles have sufficient energy so proportion of successful collisions increase
  • Collision frequency remains the same
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