Term
| Chemical Kinetics is the branch of Chemistry that addresses what two primary questions? |
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Definition
1) How fast do reactions occur? What is the rate of conversion of reactants to products?
2) What is the sequence of processes (steps) by which the conversion occurs? In other words, what is the mechanism of the reaction? |
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Term
| When one discusses the __________ of a chemical reaction one expresses the rate as the __________ in concentration of the reactants (or products) per unit time. |
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Definition
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Term
| Rate = __________ / __________ |
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Definition
1) Change of concentration
2) Change of time |
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Term
| The rate if the reaction depends on what four factors? |
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Definition
1) The nature of the reactants
2) The concentration of the reactants
3) The catalyst - present or absent
4) The temperature |
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Term
| The __________ of a reaction can be expressed in terms of decrease in concentration of the (reactants/products) per unit time or in terms of increase in the concentration of the (reactants/products) per unit time. |
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Definition
1) Rate
2) Reactions
3) Products |
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Term
| The __________ __________ is the rate of change over a certain interval of time. |
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Definition
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Term
| Rate is always a __________ number whether one speaks about disappearance of reactants or appearance of products. |
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Definition
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Term
| The __________ __________ is the rate of a reaction at a given time; in other words, when dt = 0. |
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Definition
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Term
| __________ __________ is the rate of the reaction at the very initial stage of the reaction; in other words, when the reactants are just brought together or when t=0 on the graph. |
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Definition
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Term
| The initial rate = (positive/negative) slope of the line. |
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Definition
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Term
| The __________ __________ is the highest of all rates. |
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Definition
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Term
| __________ __________ __________ are mathematical expressions that reveal how the rate of a reaction depends on the concentration of the reactants. |
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Definition
| 1) Differential Rate Laws |
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Term
| k, the rate constant of the reaction, is dependent on what three factors? |
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Definition
1) The particular reaction
2) Temperature
3) A catalyst |
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Term
| The larger the __________ value, the faster the rate of the reaction. The __________ of k depend on the orders __________ and __________ of the reaction. |
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Definition
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Term
| Zero order reactions require __________ __________ or __________. |
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Definition
1) Metal surfaces
2) Enzymes |
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Term
| __________-__________ __________ have rates that are independent of concentration; they proceed at the same rate till all the reactants have been consumed. |
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Definition
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Term
The rate of a reaction might vary depending on the __________ of the reaction, but the rate constant is a __________ value and is different for different reactions.
Rate has the unit __________ but rate constant has different units depending on the __________ of the reaction. |
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Definition
1) Order
2) Constant
3) M*s^-1
4) Units |
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Term
Effect of Order on Rate of Reaction:
1. Zero order in the reactant:
There is __________ __________ on the rate.
2. First order in the reactant:
The rate __________.
3. Second order in the reactant:
The rate __________.
4. Third order in the reactant:
The rate increases by __________. |
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Definition
1) No effect
2) Doubles
3) Quadruples
4) Eightfold |
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Term
| __________-__________ is the time required for half of the reactants to be consumed. |
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Definition
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Term
| The half-life of a __________ order reaction is independent of the initial concentration of the reactant. |
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Definition
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Term
| What are the three components necessary for a reaction to take place? |
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Definition
1) Reactants should collide
2) Reactants should have a proper orientation during collision (steric factor)
3) Reactants should collide with enough energy so that they overcome an activation barrier (activation energy) for the reaction to occur (collision theory). |
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Term
| The higher the collision frequency, the higher the __________. |
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Definition
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Term
| The __________ __________ states that reactions occur between reactant molecules if they collide with enough kinetic energy to be equal or greater than the activation energy. The orientation of the reacting species also affects the reaction rate. |
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Definition
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Term
| At higher temperatures, the __________ __________ increases somewhat, with the fraction of molecules with higher energy (to overcome the activation energy barrier) increasing resulting in a __________ rate of the reaction. |
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Definition
1) Collision frequency
2) Higher |
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Term
| The __________ __________ __________ states that collisions between molecules generate an activated complex (on top of the barrier hill) which can either revert to reactants or go to products. A reaction profile can be drawn to show graphically a plot of potential energy versus the progress of the reaction. |
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Definition
| 1) Transition State Theory |
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Term
| The higher the activation energy, the more sensitive the reaction is to __________. |
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Definition
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Term
| A __________ __________ is a stepwise description of the reaction pathway that leads to the products, and which conforms to the experimental rate law and is consistent with the stoichiometry of the overall reaction. |
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Definition
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Term
| Each of the one-step changes in the reaction mechanism is called an __________ __________. |
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Definition
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Term
| __________ of an elementary process is the number of individual atoms, molecules, or ions that must simultaneously react in that step. |
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Definition
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Term
| In a series of elementary reactions, the slowest step is called the __________ __________ __________ which controls the overall rate of the reaction |
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Definition
| 1) Rate determining step (RDS) |
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Term
| What are the four rate laws from the reaction mechanism? |
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Definition
1) A proposed mechanism must conform with the rate law determined experimentally.
2) The sum of the elementary steps in the proposed mechanism should add up to the overall stoichiometric equation.
3) In a sequence of elementary reaction the products can be formed no faster than the slowest step in the sequence. This step is called the rate determining step (RDS) - the "bottleneck."
4) A multistep sequence in a proposed mechanism produces an intermediate, which is consumed at subsequent steps. |
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Term
| __________ lower the activation energy for a reaction by changing the mechanism of the reaction (different pathway) that speeds up the reaction. They act in small amounts and are recovered at the end of the reaction. |
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Definition
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Term
| Catalysts catalyze both the __________ and __________ reactions. Although the activation energy is lowered, the dH of the reaction remains unchanged (__________ __________). |
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Definition
1) Forward
2) Reverse
3) State function |
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Term
A __________ catalyst is responsible for a single phase.
A __________ catalyst is responsible for multiple phases.
A __________ catalysts is responsible for the use of enzymes, which are high molecular weight proteins. |
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Definition
1) Homogenous
2) Heterogeneous
3) Biological |
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