Rates Of Reaction
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Activation energy?
Minimum energy required for the reaction to occur
What happens to the energy of particles at higher temperatures?
More particles have greater energy This leads to a greater rate of reaction due to more frequent successful collisions.
At lower temperatures, what is the effect on the rate of reaction?
• Fewer particles have greater energy • Rate of reaction is slower • Fewer successful collisions in a given time Lower temperatures result in decreased energy and fewer effective interactions among particles.
Define a catalyst.
A substance that increases the rate of reaction but remains unchanged at the end of the reaction Catalysts work by providing an alternative route with lower activation energy.
What is the difference between homogeneous and heterogeneous catalysts?
• Homogeneous catalysts: same state as the reactants • Heterogeneous catalysts: different state from the reactants The state of the catalyst can affect its efficiency and application in reactions.
True or false: Heterogeneous catalysts are in the same state as the reactants.
FALSE Heterogeneous catalysts are in a different state from the reactants.
How do catalysts benefit the environment?
They lower the energy demand This reduction in energy demand can lead to more sustainable chemical processes.
What does increasing the surface area do in a reaction?
• Increases the number of reactant molecules • Increases the frequency of successful collisions A larger surface area allows more reactant molecules to collide, enhancing the reaction rate.
How does increasing the temperature affect the rate of reaction?
• Molecules have more energy at higher temperatures • More molecules exceed activation energy • More frequent successful collisions Higher temperatures increase molecular movement, leading to more effective collisions.
What is the Maxwell-Boltzmann distribution?
A statistical distribution of molecular speeds in a gas It shows the spread of energies among molecules at a given temperature.
In the context of reactions, what does Ea stand for?
Activation energy It is the minimum energy required for a reaction to occur.
True or false: Only molecules with energy greater than or equal to Ea can lead to a successful reaction.
TRUE Molecules must have sufficient energy to overcome the activation barrier for a reaction to take place.
What happens to the number of molecules with energy greater than Ea as temperature increases?
The number of molecules increases Higher temperatures provide more molecules with sufficient energy to react.
What is the formula for Rates of Reaction?
Rates of Reaction = Change in concentration / Time This formula expresses how the concentration of reactants changes over time.
Increasing the concentration of reactants leads to what effect on reaction rates?
• Increases the number of reactant molecules in a given volume • Increases the frequency of collisions between molecules • More frequent successful collisions Higher concentration results in a greater likelihood of reactant interactions.
How does increasing the pressure affect reaction rates?
• More molecules in a given volume • More frequent successful collisions Pressure can be adjusted using the reaction vessel; larger volumes result in lower pressure, while smaller volumes result in higher pressure.
True or false: Lower pressure leads to more frequent successful collisions.
FALSE Lower pressure results in fewer molecules in a given volume, decreasing the likelihood of collisions.
What happens to reaction rates when pressure is increased?
Higher pressure leads to more frequent successful collisions This is due to more molecules being present in a smaller volume.
What does using lower temperatures during a reaction do to CO2 emissions?
Reduces CO2 emissions due to less fossil fuels being burned
What’s the effect of a catalyst on Boltzmann curve
Ea is lowered when catalyst used More molecules with energy greater than or equal to Ea Higher frequency of successful collisions