คำศัพท์เฉพาะทางเคมีChemical Kinetic

คำศัพท์เฉพาะทางเคมีChemical Kinetics
Reaction Rates
Part 1. Concentration Changes
Chemical kinetics is the study of the speed with which a chemical reaction occurs and the factors that affect this speed. This information is especially useful for determininghow a reaction occurs.
What is meant by the speed of a reaction? The speed of a reaction is the rate at which the concentrations of reactants and products change.
Consider the following hypothetical example. The letters A, B, and C represent chemical species (in this context, the letters do not represent elements). Suppose the following imaginary reaction occurs:
A + 2 B → 3 C
The simulation below illustrates how this reaction can be studied. The apparatus at the left is called a stopped-flow apparatus. Each syringe contains a solution filled with a different reactant (A or B). When the two solutions are forced out of the syringes, they are quickly mixed in a mixing block and the reaction starts. The reacting solution passes through the tube at the bottom. An analytical technique such as spectrophotometry is used to measure the concentrations of the species in the reaction mixture (which is in the tube at the bottom) and how those concentrations change with time.
In this example, the syringe at the left contains a solution of species A, which has a green color. The syringe at the right contains a solution of species B, which has a light blue color. The product C has a red color.
The graph at the right shows how the concentration of each species changes as time progresses. Run the simulation and observe the stopped-flow experiment and the shape of the concentration-time plots.

Notice that the color of the reaction mixture changes as the reaction progresses. The reactants are green and light blue, which when mixed produce a green color. As the reactants are consumed, the product, which is red, is produced.
This behavior is reflected in the concentration-time plots. The concentration of A, shown by the green line, decreases as time progresses, because the reaction consumes A. The same behavior is observed for B (light blue line). Conversely, there is initially no product C (red line) present. The reaction produces C, however, so the concentration of C increases as time goes by. (In this simulation, A and B were initially present in stoichiometric amounts.)
Part 2. Reaction Rate
The rate of change in the concentrations of the reactants and products can be used to characterize the rate of a chemical reaction. The rate of change in the concentration corresponds with the slope of the concentration-time plot.
The simulation below is the same as that presented above except that the slope of the concentration-time curves are also plotted on the graph. Select the species (A, B, or C) whose slope is shown and use the contols to step through the points on the graph.
In examining the simulation, answer the following questions:
• How does the slope change with time for a given species?
• Is the slope the same for all species?
• What is the sign of the slope for the reactants?
• What is the sign of the slope for the product?

Concepts
In the previous exercise the concentration-time plots showed that each species in the reaction has its own rate of change in concentration. The reactants have a negative slope, because they are being consumed in the reaction. Products have a positive slope, because they are being formed in the reaction. For the hypothetical example reaction
A + 2 B → 3 C
the stoichiometric coefficient for species B is twice that of species A; thus the concentration of B will decline twice as fast as that of species A. Similarly, the concentration of species C increases three times as fast as the concentration of A decreases.
Conceptually there should be a single, unambiguous rate for a reaction. How might such a rate be defined given the highly varied rates of change for the various species in the reaction?
The rate of reaction, r, is defined to be the slope of the concentration-time plot for a species divided by the stoichiometric coefficient of that species. Additionally, if the species is a reactant, the negative value of the slope is used, because the slope is negative and a positive rate is desired. For the example shown above
rate of reaction = r = - d [A]

d t = - 1

2 d [B]

d t = 1

3 d [C]

d t
Notice that this definition produces the same rate of reaction irrespective of which species in the reac

ผลลัพธ์ (อังกฤษ) 1:

Chemical Kinetics Chemical terminologyReaction RatesPart 1. Concentration ChangesChemical kinetics is the study of the speed with which a chemical reaction occurs and the factors that affect this speed. This information is especially useful for determininghow a reaction occurs.What is meant by the speed of a reaction? The speed of a reaction is the rate at which the concentrations of reactants and products change.Consider the following hypothetical example. The letters A, B, and C represent chemical species (in this context, the letters do not represent elements). Suppose the following imaginary reaction occurs:A + 2 B → 3 CThe simulation below illustrates how this reaction can be studied. The apparatus at the left is called a stopped-flow apparatus. Each syringe contains a solution filled with a different reactant (A or B). When the two solutions are forced out of the syringes, they are quickly mixed in a mixing block and the reaction starts. The reacting solution passes through the tube at the bottom. An analytical technique such as spectrophotometry is used to measure the concentrations of the species in the reaction mixture (which is in the tube at the bottom) and how those concentrations change with time.In this example, the syringe at the left contains a solution of species A, which has a green color. The syringe at the right contains a solution of species B, which has a light blue color. The product C has a red color.The graph at the right shows how the concentration of each species changes as time progresses. Run the simulation and observe the stopped-flow experiment and the shape of the concentration-time plots.Notice that the color of the reaction mixture changes as the reaction progresses. The reactants are green and light blue, which when mixed produce a green color. As the reactants are consumed, the product, which is red, is produced.This behavior is reflected in the concentration-time plots. The concentration of A, shown by the green line, decreases as time progresses, because the reaction consumes A. The same behavior is observed for B (light blue line). Conversely, there is initially no product C (red line) present. The reaction produces C, however, so the concentration of C increases as time goes by. (In this simulation, A and B were initially present in stoichiometric amounts.)Part 2. Reaction RateThe rate of change in the concentrations of the reactants and products can be used to characterize the rate of a chemical reaction. The rate of change in the concentration corresponds with the slope of the concentration-time plot.The simulation below is the same as that presented above except that the slope of the concentration-time curves are also plotted on the graph. Select the species (A, B, or C) whose slope is shown and use the contols to step through the points on the graph.In examining the simulation, answer the following questions:• How does the slope change with time for a given species?• Is the slope the same for all species?• What is the sign of the slope for the reactants?• What is the sign of the slope for the product?ConceptsIn the previous exercise the concentration-time plots showed that each species in the reaction has its own rate of change in concentration. The reactants have a negative slope, because they are being consumed in the reaction. Products have a positive slope, because they are being formed in the reaction. For the hypothetical example reactionA + 2 B → 3 Cthe stoichiometric coefficient for species B is twice that of species A; thus the concentration of B will decline twice as fast as that of species A. Similarly, the concentration of species C increases three times as fast as the concentration of A decreases.Conceptually there should be a single, unambiguous rate for a reaction. How might such a rate be defined given the highly varied rates of change for the various species in the reaction?The rate of reaction, r, is defined to be the slope of the concentration-time plot for a species divided by the stoichiometric coefficient of that species. Additionally, if the species is a reactant, the negative value of the slope is used, because the slope is negative and a positive rate is desired. For the example shown aboverate of reaction = r = - d [A] d t = - 1 2 d [B] d t = 1 3 d [C] d tNotice that this definition produces the same rate of reaction irrespective of which species in the reac

ผลลัพธ์ (อังกฤษ) 2:

Chemical Chemical Terminology Kinetics
Reaction Rates
Concentration Changes Part 1.
Chemical Kinetics is the Study of the speed with which a Chemical reaction occurs and the factors that affect this speed. This information is especially useful for Determininghow a reaction occurs.
What is meant by the speed of a reaction. ? The speed of a reaction is the rate at which the concentrations of reactants and products Change.
Consider the following hypothetical example. The letters A, B, and C represent Chemical species (in this context, the letters do not represent Elements). Suppose. the following Imaginary reaction occurs:
A + 2 B → 3 C
The Simulation Below Illustrates How this reaction Can be studied. The Apparatus at the left is Called a stopped-Flow Apparatus. Each Syringe contains a Solution filled with a different Reactant (A or. B). When the two solutions are forced out of the syringes, they are quickly mixed in a mixing block and the reaction starts. The reacting solution passes through the tube at the bottom. An analytical technique such as spectrophotometry is used to measure the concentrations. of the species in the reaction mixture (which is in the tube at the bottom) and How those concentrations Change with time.
In this example, the Syringe at the left contains a Solution of species A, which has a Green Color. The Syringe at. the right contains a Solution of species B, which has a Light blue Color. The product C has a Red Color.
The graph at the right shows How the concentration of each species changes As time progresses. Run the Simulation and observe the stopped-Flow. Experiment and the shape of the concentration-time plots. Notice that the Color of the reaction mixture changes As the reaction progresses. The reactants are Green and Light blue, which when Mixed Produce a Green Color. As the reactants are Consumed, the product,. which is Red, is produced. This behavior is Reflected in the concentration-time plots. The concentration of A, shown by the Green line, decreases As time progresses, because the reaction consumes A. The Same behavior is observed for B (Light blue. line). Conversely, there is initially no product C (red line) present. The reaction produces C, however, so the concentration of C increases as time goes by. (In this simulation, A and B were initially present in stoichiometric amounts. ) Part 2. Reaction first to rate The rate of Change in the concentrations of the reactants and products Can be used to characterize the rate of a Chemical reaction. The rate of Change in the concentration corresponds with the Slope of the concentration-time plot. The Simulation. below is the same as that presented above except that the slope of the concentration-time curves are also plotted on the graph. Select the species (A, B, or C) whose slope is shown and use the contols to step through the points on. the graph. In examining the Simulation, answer the following questions: • How does the Slope Change with time for a given species? • Is the Slope the Same for all species? • What is the Sign of the Slope for the reactants? • What. is the Sign of the Slope for the product? Concepts In the previous exercise the concentration-time plots Showed that each species in the reaction has ITS own rate of Change in concentration. The reactants have a Negative Slope, because they are being Consumed in the. reaction. Products have a positive Slope, because they are being formed in the reaction. For the hypothetical example reaction A + 2 B → 3 C the stoichiometric coefficient for species B is twice that of species A; thus the concentration of B Will decline twice. As fast As that species of A. similarly, increases the concentration of species C Three times the concentration of A decreases As As fast. Conceptually there should be a single, Unambiguous rate for a reaction. How Might such a rate be given the highly defined. varied Rates of Change for the Various species in the reaction? The rate of reaction, R, is defined to be the Slope of the concentration-time plot for a species divided by the stoichiometric coefficient of that species. Additionally, if the species is a. Reactant, the Negative value of the Slope is used, because the Slope is Negative and a positive rate is desired. For the example shown above rate of reaction = R = - D [A] DT = - 1 2 D [B] DT =. 1 3 D [C] DT Notice that this produces the Same Definition rate of reaction irrespective of which species in the Reac.

ผลลัพธ์ (อังกฤษ) 3:

Chemical terminology Chemical Kinetics

Reaction Rates Part 1. Concentration Changes
Chemical kinetics is the study of the. Speed with which a chemical reaction occurs and the factors that affect this speed. This information is especially useful. For determininghow a reaction occurs.
What is meant by the speed of a reaction?The speed of a reaction is the rate at which the concentrations of reactants and products change.
Consider the following. Hypothetical example. The, letters A B and C, represent chemical species (in this context the letters, do not represent. Elements). Suppose the following imaginary reaction occurs:
A 2 B - > 3 C
The simulation below illustrates how this reaction. Can be studied.The apparatus at the left is called a stopped-flow apparatus. Each syringe contains a solution filled with a different. Reactant (A or B). When the two solutions are forced out of the syringes they are, quickly mixed in a mixing block and the. Reaction starts. The reacting solution passes through the tube at the bottom.An analytical technique such as spectrophotometry is used to measure the concentrations of the species in the reaction. Mixture (which is in the tube at the bottom) and how those concentrations change with time.
In this example the syringe,, At the left contains a solution of species A which has, a green color. The syringe at the right contains a solution of species. B.Which has a light blue color. The product C has a red color.
The graph at the right shows how the concentration of each. Species changes as time progresses. Run the simulation and observe the stopped-flow experiment and the shape of the concentration-time. Plots.

Notice that the color of the reaction mixture changes as the reaction progresses. The reactants are green and light. Blue.Which when mixed produce a green color. As the reactants are, product consumed the, is, which red is produced.
This behavior. Is reflected in the concentration-time plots. The concentration, of A shown by the green line decreases as time progresses,,, Because the reaction consumes A. The same behavior is observed for B (light blue, line). ConverselyThere is initially no product C (red line) present. The reaction, produces C however so the, concentration of C increases. As time goes by. (In, this simulation A and B were initially present in stoichiometric amounts.)
Part 2. Reaction Rate
The. Rate of change in the concentrations of the reactants and products can be used to characterize the rate of a chemical reaction.The rate of change in the concentration corresponds with the slope of the concentration-time plot.
The simulation below. Is the same as that presented above except that the slope of the concentration-time curves are also plotted on the, graph. Select the species (,, A B or C) whose slope is shown and use the contols to step through the points on the graph.
In examining. The, simulationAnswer the following questions:
- How does the slope change with time for a given species?
- Is the slope the same for. All species?
- What is the sign of the slope for the reactants?
- What is the sign of the slope for the product?


, Concepts In The previous exercise the concentration-time plots showed that each species in the reaction has its own rate of change in. Concentration.The reactants have a negative slope because they, are being consumed in the reaction. Products have a, positive slope because. They are being formed in the reaction. For the hypothetical example reaction
A 2 B - > 3 C
the stoichiometric coefficient. For species B is twice that of species A; thus the concentration of B will decline twice as fast as that of species, Similarly A.The concentration of species C increases three times as fast as the concentration of A decreases.
Conceptually there should. Be a single unambiguous rate, for a reaction. How might such a rate be defined given the highly varied rates of change for. The various species in the reaction?
The rate of reaction R,,Is defined to be the slope of the concentration-time plot for a species divided by the stoichiometric coefficient of that. Species. Additionally if the, species is, a reactant the negative value of the slope, is used because the slope is negative. And a positive rate is desired. For the example shown above
rate of reaction = r = - D [A]

D T = - 1

2 D [B]

D T. 1

3 D [C]

D T
.Notice that this definition produces the same rate of reaction irrespective of which species in the reac





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