6.3 Explaining Rxn Rates Flashcards
collision theory
A theory used to explain chemical reactions in terms of effective collisions
In order for a collision to be effective:
- particles must have the proper _______
- particles must have enough ______ energy to break and re-form bonds, called the ________ energy, Ea
orientation; kinetic; activation
activation energy
minimum energy that reactant molecules must posses for a reaction to be successful.
activation energy is dependent on the ________ energy of the particles
kinetic
If molecules collide without enough energy to ________ their bonds, the reaction will _____ ____
rearrange; not occur
As temperature ________, more molecules attain the ________ energy necessary so the reaction occurs ________
increases; threshold; faster
When molecules collide with correct
orientation and enough energy to reach the _______ energy, the reactants pass through a certain point where the bonds of the ______ begin to break and the bonds of the
_______ just begin to form
This point is a ________ state and the activated _______ is formed
activation; reactants; products; transition; complex
activated complex
an intermediate molecule which occurs
when reactants are in the process of rearranging to form products
Collisions only are effective if the activated complex breaks apart in the way that ____ _______
forms products
catalyst theory
provides an alternative pathway for the
reaction, with a LOWER activation energy.
A reaction will occur between zinc and hydrochloric acid. Describe what will happen to the reaction rate under the conditions described below.
(a) The acid is cooled to 1 °C.
(a) rate decreases
A reaction will occur between zinc and hydrochloric acid. Describe what will happen to the reaction rate under the conditions described below.
(b) The reaction mixture is stirred.
(b) rate increases
A reaction will occur between zinc and hydrochloric acid. Describe what will happen to the reaction rate under the conditions described below.
(c) A concentration of 5.0 mol/L hydrochloric acid
is used instead of 1.0 mol/L.
(c) rate increases
A common catalyst that is used to speed up the
rate of the decomposition of hydrogen peroxide is powdered manganese dioxide.
(a) Describe what a catalyst is.
(a) A catalyst is a substance the increases the rate of a chemical reaction without being
consumed during the reaction.
A common catalyst that is used to speed up the
rate of the decomposition of hydrogen peroxide is powdered manganese dioxide.
(b) Explain how it affects the rate of a reaction.
(b) A catalyst affects reaction rate by providing a reaction pathway with a lower activation
energy. This increases the rate of the reaction.
