Name: how reactant concentration sets reaction rate
Uploaded: 2025-05-22T09:05:33.000Z
Duration: 2 min 33 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Physical Science

SC.912.P.12

SC.912.P.12.12

Rate Law and Reaction Order

어떤 반응이든 반응에 대해, 반응률과 반응성 농도 사이의 관계는 속도법 또는 속도 방정식을 사용하여 수학적으로 표현될 수 있다.
속도법에서'k'는비례상수또는 비율이 상수이며,'n'은단일 반응제에 대하여 반응 순서이며, 그 가치는 종종 정수이다. 다중 반응 반응에 대한 속도 법에서, 전반적인 반응 순서는 모든 반응 명령의 합이다.
각 반응제에 대해 반응 속도, 일정한 속도, 농도 및 반응 순서는 모두 실험적으로 결정됩니다.
개별 반응성 주문은 일반적으로 값 0, 1 또는 2를 취하고, 전반적인 반응 순서에 기초하여, 화학 반응은 제로 순서, 1차 또는 2차 반응으로 분류될 수 있다.
반응 속도가 지속 기간 내내 일정하게 유지되는 단일 반응, 또는 단분자 화학 반응은 제로 순서 반응입니다. 제로 오더 반응의 반응 순서는 0이며, 반응성 농도는 제로 파워로 상승한다.
제로 전력으로 상승하는 임의의 수의 값이 하나이기 때문에, 제로 오더 반응의 반응 속도는 반응성 농도와 무관하게 속도 상수와 같습니다.
반응 속도가 반응의 농도에 직접 비례하는 단분자 화학 반응은 1차 반응이다. 1차 반응에 대한 반응 순서는 하나이며, 속도법에 따라, 반응제의 농도가 첫 번째 힘으로 제기된다.
하나의 힘으로 제기된 임의의 수의 값은 동일하게 유지되기 때문에, 1차 반응의 반응속도는 반응성 농도에 직접적으로 의존한다. 반응성 농도가 감소함에 따라 반응 속도가 선형 방식으로 비례적으로 감소합니다.
반응속도가 반응의 농도의 제곱에 의존하는 단분자 화학 반응은 2차 반응이다. 반응성 농도가 감소함에 따라 반응 속도가 이차적으로 기하급수적으로 감소합니다.

속도 법칙과 반응 순서

반응 속도는 반응물의 농도에 영향을 받습니다. 속도 법칙(미분 속도 법칙) 또는 속도 방정식은 화학 반응 속도와 반응물의 농도 사이의 관계를 설명하는 수학적 표현입니다.

 예를 들어, a와 b가 화학양론적 계수인 일반 반응 aA + bB ⟶ 곱에서 속도 법칙은 다음과 같이 작성할 수 있습니다.

속도 = k[A]^m[B]^n

[A]와 [B]는 반응물의 몰 농도를 나타내고, k는 특정 온도에서 특정 반응에 특정한 속도 상수입니다.

지수 m과 n은 반응 차수이며 일반적으로 양의 정수이지만 분수, 음수 값 또는 0일 수도 있습니다.

속도 상수 k와 반응 차수 m, n은 반응물의 농도가 변함에 따라 반응 속도가 어떻게 변하는지 관찰하여 실험적으로 결정됩니다. 속도 상수 k는 반응물 농도와 무관하지만 온도에 따라 달라집니다.

속도 법칙의 반응 차수는 반응물 농도에 대한 속도의 수학적 의존성을 설명합니다. 일반 속도 법칙(rate = k[A]^m[B]^n)을 참조하면 반응은 A에 대해 m차이고 B에 대해 n차입니다. 예를 들어, m = 1이고 n = 2인 경우, 반응은 A에서는 1차이고 B에서는 2차입니다. 전체 반응 차수는 단순히 각 반응물의 차수의 합입니다. 여기에 있는 속도법칙의 경우 반응은 전체적으로 3차입니다(1 + 2 = 3).

비율 법칙을 결정하는 일반적인 실험적 접근 방식은 초기 비율 방법입니다. 이 방법에는 다양한 초기 반응물 농도를 사용하여 수행된 여러 실험 시도에 대한 반응 속도를 측정하는 작업이 포함됩니다. 이러한 시도에 대해 측정된 속도를 비교하면 반응 차수를 결정할 수 있으며, 이어서 속도 법칙을 공식화하는 데 함께 사용되는 속도 상수를 결정할 수 있습니다.

속도 법칙은 일부 반응물에 대해 분수 차수를 나타낼 수 있으며, 한 반응물의 농도가 증가하면 반응 속도가 감소할 때 때때로 음의 반응 차수가 관찰됩니다. 속도 법칙은 실험에 의해서만 결정되며 반응 화학양론으로는 확실하게 예측할 수 없다는 점에 유의하는 것이 중요합니다.

반응 차수는 반응 속도와 반응물 또는 생성물의 농도 사이의 관계를 결정합니다.

<ul style="list-style-type: disc; display: flex; flex-direction: column; gap: 10px; padding: 0 0 0 40px;">
<li>0차 반응에서는 반응물의 농도가 반응 속도에 아무런 영향을 미치지 않으며 반응 속도는 전체적으로 일정하게 유지됩니다.</li>
<li>1차 반응에서 반응 속도는 반응물 농도 변화에 정비례하고 선형적으로 비례합니다. 반응물 농도가 감소함에 따라 반응 속도도 비례적으로 감소합니다.</li>
<li>2차 또는 고차 반응에서 반응 속도는 반응물의 지수 값에 비례합니다. 따라서 반응이 진행되면서 반응물의 농도가 감소할수록 반응속도는 기하급수적으로 감소합니다.</li>
</ul>

이 문서는 에서 발췌되었습니다<a href="https://openstax.org/books/chemistry-2e/pages/12-3-rate-laws#57033">Openstax, Chemistry 2e, Section 12.3: Rate Laws</a>.

반응 속도는 반응물의 농도에 영향을 받습니다. 속도 법칙 (미분 속도 법칙) 또는 속도 방정식은 수학 표현입니다 ...

Education

교육

JoVE Core

Organic Chemistry

유기 화학

Unit 1

제1단원

Thermodynamics and Chemical Kinetics

열역학과 화학 반응 속도론

KEY TERMS AND CONCEPTS

주요 용어 및 개념

how reactant concentration sets reaction rate

Reaction rate depends on reactant concentration, and rate laws show that relationship with a mathematical equation. A rate law, also called a differential rate law or rate equation, links the rate of a chemical reaction to the concentrations of its reactants.

For a generic reaction, a A + b B  products, the rate law can be written as rate = k [A]^m [B]^n. Here, [A] and [B] are the molar concentrations of the reactants. The constant k is the rate constant, and it is specific to one reaction at a specific temperature.

The exponents m and n are the reaction orders. They are usually positive integers, but they can also be fractions, negative values, or zero. If m = 1 and n = 2, the reaction is first order in A and second order in B. The overall reaction order is the sum of the separate orders, so this example is third order overall.

Rate law values are found by experiment, not by stoichiometry. Scientists change the initial reactant concentrations in several trials and measure the reaction rate. This method, called the method of initial rates, helps determine the reaction orders and then the rate constant.

Some reactions show zero-order behavior. In a zero-order reaction, changes in reactant concentration do not change the rate, so the rate stays constant. In a first-order reaction, the rate changes in direct proportion to the reactant concentration. In second-order and higher-order reactions, the rate depends on the concentration raised to an exponent, so the rate drops more sharply as reactants are used up.

Rate laws can also show fractional orders, and some can even show negative orders. A negative order means that increasing one reactant can decrease the reaction rate. These patterns are useful for describing how reaction rate changes in real experiments. They are not reliably predicted from the reaction equation alone, so the rate law must be determined experimentally.

How Reactant Concentration Sets Reaction Rate

how-reactant-concentration-sets-reaction-rate

chemical reactions

Stoichiometry, Rates, and Equilibrium

Stoichiometry, reaction rates, and equilibrium explain how chemical reactions are measured and predicted. A balanced chemical equation shows the chemical formulas of the reactants and products in a chemical change. It also gives the relative amounts of each substance involved. Reaction stoichiometry helps predict how much reactant is needed to make a desired amount of product. It can also show how much product forms from a given amount of reactant. The amounts shown by a balanced equation are...

enthalpy and heat of reaction

Combustion Heat and Hydrocarbon Stability

Combustion is a burning reaction that releases energy as heat, light, or sound. It happens when a substance reacts with an oxidizing agent, usually molecular oxygen. The heat of combustion is also called the enthalpy of combustion. The energy released when one mole of a substance undergoes complete combustion at constant pressure is the molar heat of combustion. Combustion reactions are exothermic, so they give off energy. For that reason, the sign of ΔH is negative. In 1772, Antoine Lavoisier...

energetics of solution formation

Why Some Solutions Form Spontaneously

Solution formation can happen spontaneously under the right conditions. A spontaneous process is one that occurs without energy from an outside source. During dissolution, solute and solvent particles separate and then attract each other in a new way. The energy change depends on the balance of intermolecular forces, which are the attractions between particles. If the solute-solute and solvent-solvent forces are about the same as the new solute-solvent forces, the solution forms with no energy...

entropy and solvation

Hydrophobic Effects in Solvation

Solvation is the process of surrounding a solute with solvent. It spreads the solute evenly through the solvent. A useful rule is that like dissolves like. A good solvent has molecular features similar to the substance being dissolved. Polar solvents dissolve polar solutes, and apolar solvents dissolve apolar solutes. A polar solvent has a high dielectric constant, with ε greater than or equal to 15. An apolar solvent has a low dielectric constant. The dielectric constant is defined by the...

gibbs free energy and thermodynamic favorability

gibbs-free-energy-and-thermodynamic-favorability

Temperature Effects on Gibbs Free Energy

Temperature changes can decide whether a process is spontaneous. This idea applies to phase changes and to some chemical reactions. The key link is Gibbs free energy, which connects free energy change with enthalpy and entropy. The sign of the Gibbs free energy change, or ΔG, depends on the signs of enthalpy change (ΔH) and entropy change (ΔS), and sometimes on the absolute temperature. Because temperature is measured in kelvin, it is always a positive value. That means there are four main...

chemical and solubility equilibria

How Solubility Depends on Free Energy

Solubility depends on free energy changes when a solute dissolves in a solvent. The free energy change for this process is called the free energy of solution, ΔGsolution. When ΔGsolution is less than zero, solution formation is favorable. When it is greater than zero, solution formation is unfavorable. For complete dissolution to happen, the Gibbs energy change must be negative. This means the balance of forces in the mixture must favor solution formation. The amount a solute dissolves in a...

rate law and reaction order

Reaction rate depends on reactant concentration, and rate laws show that relationship with a mathematical equation. A rate law, also called a differential rate law or rate equation, links the rate of a chemical reaction to the concentrations of its reactants. For a generic reaction, a A + b B  products, the rate law can be written as rate = k [A]^m [B]^n. Here, [A] and [B] are the molar concentrations of the reactants. The constant k is the rate constant, and it is specific to one reaction at...

effect of temperature change on reaction rate

effect-of-temperature-change-on-reaction-rate

Arrhenius Equation in Reaction Speed

The Arrhenius equation connects activation energy, temperature, and the rate constant, k, for many chemical reactions. It helps explain why some reactions move slowly while others happen faster. In this equation, R is the ideal gas constant, with a value of 8.314 J/mol·K. T is the temperature in kelvin, Ea is the activation energy in joules per mole, e is the constant 2.7183, and A is the frequency factor. The frequency factor, A, describes how often reacting molecules collide and how well...

multi-step reactions

Reaction Mechanisms and Rate-Determining Steps

Chemical reactions can happen in a sequence of steps. A balanced chemical equation shows the reactants and products, but it does not show how the reaction occurs at the molecular level. The reaction mechanism, or reaction path, gives that step-by-step detail. Each step in a mechanism is an elementary reaction. These elementary reactions happen in order, and together they add up to the balanced equation for the overall reaction. In a multistep mechanism, one step is often much slower than the...

bond dissociation energy and activation energy

bond-dissociation-energy-and-activation-energy

How Bond Strength Shapes Reaction Speed

Bond strength and activation energy help explain why organic reactions happen. Bond energy is the energy needed to break a bond homolytically, which means each atom takes one of the shared electrons. When a bond value is given for one specific bond, it is called bond dissociation energy. When it is given for a bond type across many compounds, it is called average bond energy. Bond dissociation energy usually follows a clear pattern. A single bond is weaker than a double bond, and a double bond...

energy diagrams, transition states, and intermediates

energy-diagrams-transition-states-and-intermediates

Reaction Coordinate Diagrams in Chemical Reactions

Reaction coordinate diagrams show how energy changes during a chemical reaction. These free-energy graphs use the horizontal axis to show reaction progress. Points near the reactants look like the reactants, while points near the products look like the products. The peaks on the diagram represent stable structures with measurable lifetimes. Other points on the curve are unstable and cannot be isolated. The high-energy, unstable peak is called the transition state, or activated complex. At the...

predicting reaction outcomes

How Temperature Changes Reaction Rate

Reaction rate and reaction pathway are key ideas in chemical kinetics. Thermodynamics, by contrast, focuses on the state of a system. It describes the properties, behavior, and components of reactants and products. It does not describe the path of the process or the speed of the reaction. Kinetics gives information on the atomic or molecular level, while thermodynamics focuses on the energetics of the reactants and products. Thermodynamics can show what may happen in a reaction, but it does...

key terms and concepts

Learn how rate laws connect reactant concentration to reaction speed, how reaction orders work, and how the method of initial rates is used to find them.

How Reactant Concentration Sets Reaction Rate | JoVE K12

organic chemistry

JoVE Core Organic Chemistry explains basic concepts of stereochemistry, reactions, and mechanisms using concise and easy-to-understand animated video lessons. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

Introduction to Scalars

Many familiar physical quantities can be specified completely by giving a single number and the appropriate unit. For example, &#34;a class period lasts ...

Introduction to Vectors

To define some physical quantities, there is a need to specify both magnitude as well as direction. For example, when the U.S. Coast Guard dispatches a ...

vector-components-in-the-cartesian-coordinate-system

Vector Components in the Cartesian Coordinate System

Vectors are usually described in terms of their components in a coordinate system. Even in everyday life, we naturally invoke the concept of orthogonal ...

Vector Algebra: Graphical Method

Vectors can be multiplied by scalars, added to other vectors, or subtracted from other vectors. The vector sum of two (or more) vectors is called the ...

Vector Algebra: Method of Components

It is cumbersome to find the magnitudes of vectors using the parallelogram rule or using the graphical method to perform mathematical operations like ...

/files/media/science-education/science-education-thumbs/12613.jpg

Scalar Product (Dot Product)

The scalar multiplication of two vectors is known as the scalar or dot product. As the name indicates, the scalar product of two vectors results in a ...

Vector Product (Cross Product)

Vector multiplication of two vectors yields a vector product, with the magnitude equal to the product of the individual vectors multiplied by the sine of ...

Scalar and Vector Triple Products

Two vectors can be multiplied using a scalar product or a vector product. The resultant of a scalar product is scalar, while with vector products, the ...

/files/media/science-education/science-education-thumbs/14688.jpg

Gradient and Del Operator

In mathematics and physics, the gradient and del operator are fundamental concepts used to describe the behavior of functions and fields in space. The ...

/files/media/science-education/science-education-thumbs/14689.jpg

Divergence and Curl

The divergence of a vector field at a point is the net outward flow of the flux out of a small volume through a closed surface enclosing the volume, as ...

/files/media/science-education/science-education-thumbs/14690.jpg

Second Derivatives and Laplace Operator

The first order operators using the del operator include the gradient, divergence and curl. Certain combinations of first order operators on a scalar or ...

/files/media/science-education/science-education-thumbs/14692.jpg

Line, Surface, and Volume Integrals

A line integral for a vector field is defined as the integral of the dot product of a vector function with an infinitesimal displacement vector along a ...

/files/media/science-education/science-education-thumbs/14693.jpg

Distinguish between scalar and vector quantities and assess which should be used to describe an event.

SC.912.P.12.1

Position and Displacement

The position of an object defines its location relative to a convenient frame of reference at any particular time. A frame of reference is an arbitrary ...

Average Velocity

To calculate the other physical quantities in kinematics, we must introduce the time variable. The time variable allows us not only to state the position ...

Instantaneous Velocity - I

The average velocity during a time interval cannot tell us how fast or in what direction a particle is moving at any given time during the interval. To ...

Instantaneous Velocity - II

Instantaneous velocity is the quantity that measures how fast an object is moving along its path. In other words, the instantaneous velocity of an object ...

Average Acceleration

The importance of understanding acceleration spans our day-to-day experiences, as well as the vast reaches of outer space and the tiny world of subatomic ...

Instantaneous Acceleration

Acceleration is in the direction of the change in velocity, but it is not always in the direction of motion. When an object slows down, its acceleration ...

Kinematic Equations - I

When an object moves with constant acceleration, the velocity of the object changes at a constant rate throughout the motion. The kinematic equations of ...

Kinematic Equations - II

The second kinematic equation expresses the final position of an object in terms of its initial position, the distance traveled with the initial constant ...

Kinematic Equations - III

The first two kinematic equations have time as a variable, but the third kinematic equation is independent of time. This equation expresses final velocity ...

Kinematic Equations: Problem Solving

When analyzing one-dimensional motion with constant acceleration, the problem-solving strategy involves identifying the known quantities and choosing the ...

Free-falling Bodies: Introduction

All objects, neglecting air resistance, fall with the same acceleration towards the Earth&#39;s center due to the force exerted by the Earth&#39;s ...

Free-falling Bodies: Example

An object falling without any air resistance under the influence of gravitational force is said to be in free-fall. For free-falling bodies, the ...

velocity-and-position-by-graphical-method

Velocity and Position by Graphical Method

Velocity and position can be calculated from the known function of acceleration as a function of time. The total area under the acceleration-time graph ...

Non-uniform Circular Motion

In&#160;uniform circular motion, the particle executing circular motion has a constant speed, and the circle is at a fixed radius. However, not all ...

Velocity and Position by Integral Method

If acceleration as a function of time is known, then velocity and position functions can be derived using integral calculus. For constant acceleration, ...

Relative Velocity in One Dimension

The understanding of the concept of reference frames is essential to discuss relative motion in one or more dimensions. When we say that an object has a ...

Position and Displacement Vectors

To describe the motion of an object, one should first be able to describe its position (where it is at any particular time). More precisely, the position ...

Relative Velocity in Two Dimensions

Relative velocity is the velocity of an object as observed from a particular reference frame, or the velocity of one reference frame with respect to ...

average-and-instantaneous-velocity-vectors

Average and Instantaneous Velocity Vectors

To calculate other physical quantities in kinematics, the time variable must be introduced. The time variable not only allows us to state where an object ...

Acceleration Vectors

In everyday conversation, accelerating means speeding up. Acceleration is a vector in the same direction as the change in velocity, &#916;v, therefore the ...

Direction of Acceleration Vectors

Acceleration occurs when velocity changes in magnitude (an increase or decrease in speed), direction, or both. Although acceleration is in the direction ...

Projectile Motion

An object thrown in the air follows a parabolic path under the influence of Earth&#39;s gravitational force. The motion of such an object is called ...

/files/media/science-education/science-education-thumbs/12634.jpg

Projectile Motion: Equations

Projectile motion is commonly observed in our day-to-day life. For example, a basketball thrown by a player, an arrow shot from a bow, and kids jumping ...

Projectile Motion: Example

The theory of projectile motion is very useful for players of several sports to improve their performance. For example, a javelin thrower needs to throw ...

Uniform Circular Motion

Uniform circular motion is a specific type of motion in which an object travels in a circle with a constant speed. For example, any point on a propeller ...

Analyze the motion of an object in terms of its position, velocity, and acceleration (with respect to a frame of reference) as functions of time.

SC.912.P.12.2

Newton's First Law: Introduction

Motion draws our attention. Motion itself can be beautiful, causing us to marvel at the forces needed to create spectacular sights, such as that of a ...

Newton's First Law: Application

Experience suggests that an object at rest remains at rest if left alone, and that an object in motion tends to slow down and stop unless some effort is ...

Internal and External Forces

Newton&#39;s first law states that a net external force causes a change in motion. External forces act on an object or system, originating outside of the ...

Newton's Second Law

Newton&#39;s second law is closely related to his first law of motion. It mathematically gives the cause-and-effect relationship between force and changes ...

Newton's Third Law: Introduction

Whenever one body exerts a force on a second body, the first body experiences a force equal in magnitude and opposite in direction, to the force that it ...

Newton's Third Law: Examples

Newton&#39;s third law states that every action has an equal and opposite reaction. Consider a swimmer pushing off the side of a pool. They push against ...

Inertial Frames of Reference

Newton&#8217;s first law is usually considered to be a statement about reference frames. It provides a method for identifying a special type of reference ...

Non-inertial Frames of Reference

A reference frame accelerating or decelerating relative to an inertial frame is a non-inertial frame. To help understand this, consider what taking off in ...

first-law-particles-in-one-dimensional-equilibrium

First Law: Particles in One-dimensional Equilibrium

Newton&#39;s first law of motion states that a body at rest remains at rest, or if in motion, remains in motion at constant velocity, unless acted on by a ...

first-law-particles-in-two-dimensional-equilibrium

First Law: Particles in Two-dimensional Equilibrium

Recall that a particle in equilibrium is one for which the external forces are balanced. Static equilibrium involves objects at rest, and dynamic ...

Second Law: Motion under Same Force

Newton&#39;s laws can be applied to bodies at rest and bodies in motion. Newton&#39;s first law is applied to bodies in equilibrium, whereas the second ...

second-law-motion-under-same-acceleration

Second Law: Motion under Same Acceleration

Newton&#39;s second law of motion applies to bodies moving under the same acceleration. For example, when a baggage tractor pulls luggage carts, each cart ...

Interpret and apply Newton's three laws of motion.

SC.912.P.12.3

Gravitation

In the years before Newton, a general belief prevailed that different laws governed objects in the sky than objects on Earth. When Kepler wrote down the ...

/files/media/science-education/science-education-thumbs/14716.jpg

Newton's Law of Gravitation

Our everyday observation tells us that all objects close to the Earth naturally tend to fall to the ground. Early philosophers assumed that this downward ...

gravitation-between-spherically-symmetric-masses

Gravitation Between Spherically Symmetric Masses

The gravitational potential energy between two spherically symmetric bodies can be calculated from the masses and the distance between the bodies, ...

/files/media/science-education/science-education-thumbs/14717.jpg

Gravity between Spherical Bodies

Newton&#39;s law of gravitation describes the gravitational force between any two point masses. However, for extended spherical objects like the Earth, ...

Describe how the gravitational force between two objects depends on their masses and the distance between them.

SC.912.P.12.4

Linear Momentum

The term momentum is used in various ways in everyday language, most of which are consistent with the precise scientific definition. Generally, momentum ...

Apply the law of conservation of linear momentum to interactions, such as collisions between objects.

SC.912.P.12.5

A. Motion can be measured and described qualitatively and quantitatively. Net forces create a change in motion. When objects travel at speeds comparable to the speed of light, Einstein's special theory of relativity applies.

B. Momentum is conserved under well-defined conditions. A change in momentum occurs when a net force is applied to an object over a time interval.

C. The Law of Universal Gravitation states that gravitational forces act on all objects irrespective of their size and position.

D. Gases consist of great numbers of molecules moving in all directions. The behavior of gases can be modeled by the kinetic molecular theory.

E. Chemical reaction rates change with conditions under which they occur. Chemical equilibrium is a dynamic state in which forward and reverse processes occur at the same rates.

How Reactant Concentration Sets Reaction Rate

Description

Transcript

Tags

More videos by Standards