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19 terms

Ch. 14, Chemical Kinetics

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What is the equation for rate reactions?
[(∆)Something changing]/[Change in(∆) time]
If a rxn rate is decreasing in concentration, what will the sign infront of the equation be?
-
If a rxn rate is increasing in concentration, what will the sign infront of the equation be?
+
What is the equation for rate laws?
rate=k[reactant]^m[reactant]^n; k is determined experimentally
Rate __/Rate __
2/1
What is the equation for solving for k?
K= rate/([react]^m[react]^n)
What is the equation for First-Order Reactions
rate= -∆[X]/∆t(←time) = k[X]^1
What is the equation for Second-Order Reactions
rate= -∆[X]/∆t(←time) = k[X]^2
What is the equation for Zero-Order Reactions
rate= k[react]^0 = k; [react] = -kt + [react]˅0
What is the equation for Third-Order Reactions
rate= k[X]^3
What two things need to be present for reactions to occur?
Collisions, Collisions with proper orientation
Define activation energy
Minimum energy required for collisions to be productive
When a bond is breaking, is it endo or exo, and is energy being given to or taken from the surroundings?
Endo, energy is given off to surroundings
When a bond is forming, is it endo or exo, and is energy being given to or taken from the surroundings?
Exo, energy taken from surroundings
On the reaction pathway, name the normal steps (A-E &Ea)
Step A = reactants, Step B = Activated complex, Ea, Step C = intermediate (more stable than B & D), Step D = activated complex, Ea, Step E = Products, Step Ea = Reverse, D, C, etc..
What directly influences rate constant?
Temperature
Why does k increase with increasing temperatures?(4 reasons)
1. Greater avg velocity & greater avg KE, 2. Increases in frequency of collisions, 3. Increase in number of collisions with proper orientation, 4. Increases number of collisions with sufficient energy
What is the Arrhenius equation?
k = Ae^(-Ea/RT); ln(k) = (-Ea/R)(1/T) + ln(A)
What does A mean in the Arrhenius equation
A is the frequency factor; frequency of collisions, fraction of collisions with proper orientation