General Chemistry Chapter 5: Chemical Kinetics Flashcards Preview

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Flashcards in General Chemistry Chapter 5: Chemical Kinetics Deck (17)
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1

What is the Gibbs free energy?

determines whether or not a reaction is spontaneous

2

Intermediates

molecules that exist within the course of a reaction, but are neither reactants nor products overall.

3

What is the slowest step?

Rate-determining step - limits the maximum rate at which the reaction can proceed.

4

What is the collision theory?

A reaction rate is proportional to the number of effective collisions between the reacting molecules
1. proper orientation
2. sufficient kinetic energy to exceed Ea

5

What is the Arrhenius equation?

A mathematical way of representing collision theory

6

What is the transition state theory?

states that molecules form a transition state or activated complex during a reaction in which the old bonds are partially dissociated and the new bonds are partially formed.

7

What is the highest point of free energy in a reaction?

The transition state

8

What can affect the reaction rate?

1. Increasing the concentration of reactant = increase r.r. because more collisions
2. Increasing the temperature = increase r.r. because more kinetic energy
3. changing the medium
4. adding a catalyst = increase r.r.

9

Homogeneous catalyst

same phase as the reactants

10

Heterogeneous catalyst

different phase

11

How are rate orders determined?

Must be determined via experimental data - generally do not match the stoichiometric coefficients

12

What is the rate order?

the sum of all individual rate orders in the late law

13

What are zero-order reactions?

Have a constant rate that does not depend on the concentration
- Can only be affected by changing temp or adding a catalyst
- curve = straight line w/ a slope -k

14

What are first-order reactions?

Have a non-constant rate that depends on the concentration of reactant.
- Non-linear
- Slope of a ln [A] v. time is -k

15

What is a second-order reaction?

have a nonconstant rate that depends on the concentration
- Non-linear
Slope of 1/[A] is k

16

What is a broken-order reaction?

non-interger orders

17

What is a mixed order reaction?

have a rate order that changes over time.