kinetics Flashcards
describe a chemical reaction in terms of collision theory
reactions occur when reactant particles collide with sufficient energy called activation energy
define activation energy
the minimum energy needed for a chemical reaction to occur and collision to be successful
explain why most collisions between particles do not result in a chemical reaction
the energy of reactant particles is distributed with very few having energy >= activation energy
why does the maxwell-boltzman graph start at the origin?
because there are no particles that have 0 kinetic energy
why does a raise in temperature result in an increase in rate of reaction?
at a higher temperature, more particles have energy greater than or equal to the activation energy, so more collisions are successful
define rate of reaction
the change in the amount of reactant or product per unit time
explain how a reaction between HCl and sodium thiosulfate can be monitored
the reaction produces a sodium ppt, so measure the time it takes for the ppt to obscure the cross. rate = 1/time
explain why the reaction between HCl and sodium thiosulfate has to be kept small scale
toxic sulfur dioxide is the product
how does increasing the concentration affect the rate of reaction?
increased rate of reaction as increased number of reactant particles per unit volume so increased number of successful collisions per unit time
how does increasing the pressure affect the rate of reaction?
increased rate of reaction as increased number of reactant particles per unit volume so increased number of successful collisions per unit time
define catalyst
a substance that increases rate of reaction without being permanently changed or used up
how do catalysts work?
provides an alternative reaction pathway with a lower activation energy so more particles have energy greater than or equal to the activation energy
