topic 2: controlling the rate Flashcards
state the two conditions required for a successful collision
-the activation energy for the reaction is achieved
-the reactant modules achieve the correct geometry (orientation) so they are facing the correct way to react
define activation energy
the minimum energy required by colliding particles to form an activated complex
what is temperature a measure of
the average kinetic energy of the particles in a substance
what does a catalyst provide
an alternative reaction pathway with a lower activation energy
how does using a catalyst increase reaction rate
more particles will therefore achieve the lower activation energy so reaction rate will increase
what does a potential energy diagram show
the energy pathway for a reaction and how the energy of the chemical series taking part in a reaction change as it changes from reactants to products
what is enthalpy change
the difference in potential energy between reactants and products
what is an exothermic reaction
a reaction that releases energy usually in the form of heat
explain why exothermic reactions release heat
in an exothermic reaction, the formation of new bonds in the product releases more energy then was used to create the original bonds of the reactants. as a result, energy is released from the reaction system to the surroundings
in an exothermic reaction what will the enthalpy change always be what
negative
what is an endothermic reaction
a reaction that takes in energy
explain why endothermic reactions take in energy
in an endothermic reaction the formation of new bonds in the product releases less energy than was used to break the original bonds of the reactants. as a result, the reaction absorbs energy from the surrounding
in an endothermic reaction what will the enthalpy change always be what
positive
