kinetics Flashcards
(13 cards)
what is collision theory?
when two particles collide in the right direction and collide with a certain minimum amount of kinetic energy.
what is activation energy?
-the minimum amount of kinetic energy particles need to react.
-this is needed to break bonds in reactants
what is the Maxwell-boltzmann distribution?
a graph of the numbers of molecules in a gas with different kinetic energies.
what effect does temperature have on reaction rate?
-if you increase the temperature of gas, molecules will have more kinetic energy so move faster, so more molecules have the activation energy, more frequent collisions, pushing the Maxwell-boltzmann curve to the right.
-if you decrease the temperature of gas, molecules will have less kinetic energy and move slower, so less molecules have the activation energy, pushing the Maxwell-boltzmann curve to the left.
what effect does concentration have on reaction rate?
-if you increase the concentration, more particles in the same volume/particles will be closer together, collisions are more frequent, so more successful collision/more chances to react, this raises the Maxwell-boltzmann curve.
-if you decrease the concentration, particles will be further away from each other, so collisions are less frequent, so less chances to react, this lowers the Maxwell-boltzmann curve.
what effect does pressure have on reaction rate?
-if you increase the pressure, more particles in the same volume/particles will be closer together, collisions are more frequent, so more successful collision/more chances to react, this raises the Maxwell-boltzmann curve.
-if you decrease the pressure, particles will be further away from each other, so collisions are less frequent, so less chances to react, this lowers the Maxwell-boltzmann curve.
what effect does surface area have on reaction rate?
greater surface to collide, so greater frequency of collisions so more successful collisions.
what effect does a catalyst have on reaction rate?
allows a different reaction pathway that has a lower activation energy, so more particles have the activation/sufficient energy so greater frequency of collisions
what is a catalyst?
increases the rate of a reaction by providing an alternative reaction pathway with a lower activation energy, chemically unchanged at the end of the reaction.
how do catalysts work?
lowers the activation energy so more particles have enough energy to react when they collide, allows reaction to go via different route.
what is rate of reaction?
the change in the amount of a reactant or product over time.
what is the equation for rate of reaction?
rate of reaction= amount of reactant or product formed/ time
describe a practical for the time taken for a precipitate to form.
-stand a conical flask on a white tile with a black mark on it
-add volumes of sodium thiosulfate and hydrochloric acid
-start the timer and stop it when a yellow precipitate covers the black mark
