Collision Theory
The set of assumptions regarding collisions and reactions between molecules
What is collision theory?
The step-by-step sequence of reactions by which the overall chemical change occurs
What is reaction mechanism?
Represents an exothermic reaction change in energy
What is a negative ΔE?
What is a catalyst?
The following reaction is first order: (CH2)3(g) --> CH2CHCH3(g)
Find the change in reaction rate is the pressure of (CH2)3 is doubled.
What is an increase by a factor of 2?
The two conditions that must be met for a collision to be effective in producing a new chemical species
What are energetic enough to supply the necessary activation energy and oriented in a way that favors their efficient interaction?
A reaction whose reactants and products exist in a single phase
What is a homogeneous reaction?
Type of reaction if the products are higher on the energy diagram than the reactants
What is endothermic?
The power to which a reactant concentration is raised
What is the order of that reactant?
A reaction that involves reactants A and B is found to occur in the one-step mechanism: 2A + B --> A2B.
Write the rate law for this reaction, and predict the effect of doubling the concentration of either reactant on the overall reaction rate.
In terms of energy, the activated complex forms at this point along a typical reaction pathway
What is the maximum energy position (highest point in the energy diagram)?
Species that appear in some steps by not in the net equations
What are intermediates?
If Ea is 125 kJ/mol, and Ea' is 35 kJ/mol, the ΔE is this
and the reaction is this type
What is 90 kJ/mol and endothermic?
An equation that relates reaction rate and concentrations of reactants
What is the rate law?
A + 2B --> C; 3 experiments are conducted. In experiment 1, [A] = 0.20M, [B] = 0.20 M, and R = 2.0 x 10-4 M/min. In experiment 2, [A] = 0.20 M, [B] = 0.40 M, and R = 8.0 x 10-4 M/min. In experiment 3, [A] = 0.40 M, [B] = 0.40 M, and R = 1.6 x 10-3 M/min. Determine the rate law and calculate k.
What is R= k[A][B]2; k= 2.5 x 10-2 M-2/min ?
The amount of energy necessary to form the activated complex
What is activation energy?
A transitional structure that results from an effective collision and persists while old bonds are breaking and new bonds are forming.
What is an activated complex?
If the ΔE is -100 kJ/mol, and the Ea' is 145 kJ/mol, the Ea is this.
What is 45 kJ/mol?
The method by which a catalyst changes the rate of the chemical reaction
What is lowers the activation energy (provides an alternate pathway)?
The reaction CH3NC(g) -> CH3CN(g) is first order. The rate of this reaction is 1.3 x 10-4 M/s when the reactant concentration is 0.040 M. Predict the rate when [CH3CN] = 0.025 M
What is 8.1 x 10-5 M/s?
In order for reactions to occur between substances, these must collide and those collisions must result in this
What are particles (ions, atoms, or molecules) and interactions?
The difference between an activated complex and an intermediate
What is in an activated complex, bonds are partially broken and partially formed, so the complex represents a maximum on the energy diagram whereas an intermediate is a distinct molecular species that is formed in one step of a reaction and reacts in a subsequent step?
The relationship between Ea, Ea', and ΔE
What is Ea=ΔE+Ea' or Ea-Ea'=ΔE?
5 important factors that influence reaction rate
What are nature of reactants, surface area, temperature, concentration, and presence of a catalyst?
For the reaction A + B --> C, when the initial concentration of A was doubled from 0.100 M to 0.200 M, the rate changed from 8.0 x 10-5 to 6.4 x 10-4. Find the rate law and the rate constant for this reaction.
What are rate = k[A]3 and k= 8.0 x 10-2 M-2s-1?