CHMB16H3 Lecture Notes - Activated Complex, Rate Equation, Reaction Intermediate

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ochrefrog126

26 Jun 2012

School

UTSC

Department

Chemistry

Course

CHMB16H3

Professor

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Document Summary

The rate of a reaction describes how fast the concentration of a reactant or product changes with time. Rate of formation = [c]/ t: rate of disappearance is a negative quantity because concentration decreases with time. Rate of disappearance = - [a]/ t: the concentration at the end of a time period is less than t was at the start of the period. To determine rate of reaction, we need to measure changes in concentration over time: reaction rate is not constant; the lower the remaining concentration of the reactant, the more slowly the reaction proceeds. Instantaneous rate of reaction- is the exact rate of a reaction at some precise point in the reaction. It is obtained from the slope of a tangent line to a concentration-time graph. Initial rate of reaction- is the rate of a reaction immediately after the reactants are brought together o o o.

Related Questions

The rate of reaction indicates the speed at which the reaction can occur. It can be expressed in terms of a change in the concentration of reactants or products per unit of time:

rate = concentration changetime change

The rate of reaction can be defined either as a decrease in the concentration of a reactant per unit of time or as an increase in the concentration of a product per unit of time.

Select the image to explore the activity that shows the different ways in which the rate of a reaction can be expressed.

When you click on the "Disappearance of reactants," "Appearance of products," or "Rate law expression" button, you will observe different expressions for the rate of the reaction.

Consider the following reaction:

2A+3Bâ3C+2D

Use the following data to determine the rate of reaction in terms of the disappearance of reactant A at time = 20 s.

Time (s)	0	20	40
[A](M)	0.1200	0.0720	0.0540

Express your answer in molar concentration per second to three significant figures.

Part B

Consider the following reaction:

2A+3Bâ3C+2D

Use the following data to determine the rate of reaction in terms of the appearance of product C when the time is 20 s.

Time (s)	0	20	40
[C](M)	0.000	0.0720	0.1440

Show transcribed image text

You study the rate of a reaction, measuring both the concentration of the reactant and the concentration of the product as a function of time, and obtain the following results:

(a) Which chemical equation is consistent with these data:
(i) A B, (ii) B A, (iii) A 2 B,
(iv) B 2 A?
(b) Write equivalent expressions for the rate of the reaction in terms of the appearance or disappearance of the two substances.

violetrhinoceros455

(a) Select all of the correct statements about reaction rates fromthe choices below.

A)The lower the rate of a reaction the longer it takes to reachcompletion.

B)Catalysts increase reaction rates.

C)Reaction rates are determined by reactant concentrations,temperatures, and reactant stabilities.

D)Concentrations of homogeneous catalysts have no effect onreaction rates.

E)A balanced chemical reaction is necessary to relate the rate ofdisappearance of a reactant to the rate of appearance of aproduct.

F)Reaction rates can show little change as masses of solidreactants increase.

G)Reaction rates always increase as masses of solid reactantsincrease.

CHMB16H3 Lecture Notes - Activated Complex, Rate Equation, Reaction Intermediate

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