Name: stoichiometry, rates, and equilibrium
Uploaded: 2023-04-30T18:28:32.000Z
Duration: 2 min 26 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry and Physics

IPC.8

IPC.8.A

Chemical Reactions

Hidrojen gazının yanması gibi dengeli bir kimyasal reaksiyonu düşünün. Burada, reaktanlar ve ürünler arasındaki kantitatif ilişki — H2, O2 ve H2O — iki H2 molekülünün bir molekül O2 ile reaksiyona girerek iki Hmolekülü2 O üretmesidir. Bu nicel ilişki stokiyometri olarak bilinir.
Kimyasal bir reaksiyonda, reaktanlar ürünler oluşturmak için birbirleriyle etkileşime girerler. Tamamen tüketilen reaktan, sınırlayıcı reaktandır ve sınırlayıcı reaktan ile tamamen reaksiyona girmek için gerekenden daha büyük bir miktarda bulunan reaktan, fazla reaktandır.
Kimyasal bir reaksiyon, reaktanların ürünlere kimyasal dönüşümünü içerir. Reaksiyon ilerledikçe, ürünlerin konsantrasyonu artarken reaktanların konsantrasyonu azalır. Reaktanların ve ürünlerin konsantrasyonlarındaki bu varyans, zamanın bir fonksiyonu olarak bir grafikte çizilebilir.
Bir reaksiyonun ilerleme hızına reaksiyon hızı denir. Reaktanların kaybolma oranını veya ürünlerin ortaya çıkma oranını ölçer ve saniyede molarite birimleriyle ifade edilir.
Tersinir bir kimyasal reaksiyon, reaktanların ürünlere dönüştürülmesinin ve ürünlerin tekrar reaktanlara dönüştürülmesinin aynı anda gerçekleştiği bir reaksiyondur. Reaktanlar ve ürünler arasındaki çift ok, tersinir doğasını gösterir.
Ürünlerin oluşum hızı veya ileri reaksiyonun hızı, reaktanların oluşum hızına veya ters reaksiyonun hızına eşit olduğunda, kimyasal denge elde edilir.
Denge sabiti ifadesi, C ve D ürünlerinin, dengedeki reaktanlar, A ve B üzerinde, her biri kendi stokiyometrik katsayılarına yükseltilen molar konsantrasyonları olarak yazılır. Çözüldüğünde, ifade denge sabiti olan Kc'ye eşittir.
Aynı formda bir ifade, herhangi bir konsantrasyondaki reaktanlar ve ürünler için de yazılabilir ve hesaplanan miktar, reaksiyon katsayısı, Qc olarak bilinir.

kimyasal reaksiyonlar

Dengeli bir kimyasal denklem, kimyasal değişime katılan reaktanların ve ürünlerin kimyasal formülleri hakkında bilgi sağlar. Bir reaksiyonun stokiyometrisi, istenen miktarda ürünü üretmek için ne kadar reaktana ihtiyaç duyulduğunu veya bazı durumlarda belirli bir miktarda reaktandan ne kadar ürün oluşacağını tahmin etmeye yardımcı olur.

 Dengeli bir kimyasal denklemde temsil edilen reaktanların ve ürünlerin bağıl miktarlarına genellikle stokiyometrik miktarlar denir. Ancak gerçekte reaktanlar her zaman dengeli denklemin gösterdiği stokiyometrik miktarlarda mevcut değildir.

 Bir kimyasal reaksiyonda ilk önce tüketilen ve oluşan ürün miktarını sınırlayan reaktan sınırlayıcı reaktan olurken, diğer madde fazla reaktan haline gelir. Diğer reaktantın ürüne tamamen dönüşmesini sağlamak için sıklıkla bir veya daha fazla reaktantın fazlası kullanılır.

 Denklemin temsil ettiği su oluşumu reaksiyonunu düşünün:

<img alt="Eq1" src="/files/ftp_upload/11691/11691_Equation1.svg" style="text-align: center; height: 20px;">

 Stokiyometri, iki mol hidrojen ve bir mol oksijenin reaksiyona girerek iki mol su ürettiğini gösterir; yani hidrojen ve oksijen 2:1 oranında birleşir.

 5 mol hidrojen ve 2 mol oksijenin mevcut olduğunu hayal edin. Reaktiflerin oranı artık 5:2'dir (veya 2,5:1), bu da 2:1'lik stokiyometrik orandan daha yüksektir. Bu nedenle hidrojen fazla miktarda mevcuttur ve oksijen sınırlayıcı reaktandır. Sağlanan tüm oksijenin (2 mol) reaksiyonu, sağlanan 5 mol hidrojenin 4 molünü tüketecek ve reaksiyona girmemiş 1 mol hidrojen kalacaktır. Sağlanan her bir reaktanın molar miktarını hesaplamak ve bunları dengeli kimyasal denklemde temsil edilen stokiyometrik miktarlarla karşılaştırmak, sınırlayıcı ve fazla reaktanları tanımlamanın bir yoludur.

 Reaksiyon hızı, birim zamanda bir reaktan veya ürünün miktarındaki değişikliktir. Bu nedenle reaksiyon hızları, reaktan veya ürün miktarları ile ilişkili olabilecek bazı özelliklerin zamana bağımlılığı ölçülerek belirlenir.

<img alt="Figure1" src="/files/ftp_upload/11691/11691_Figure1.png" style="text-align: center; height: 300px;">

 Bir kimyasal reaksiyonun hızı, zamanın bir fonksiyonu olarak reaktanların ve ürünlerin konsantrasyonlarındaki değişiklik olarak bir grafikte çizilebilir.

 Tersinir bir kimyasal reaksiyon, hem ileri (soldan sağa) hem de ters (sağdan sola) yönde ilerleyen bir kimyasal işlemi temsil eder. Geri dönüşümlü bir reaksiyonun durumu, reaksiyon katsayısı (Q) değerlendirilerek uygun şekilde değerlendirilir. Tarafından açıklanan geri dönüşümlü bir reaksiyon için

<img alt="Eq2" src="/files/ftp_upload/11691/11691_Equation2.svg" style="text-align: center; height: 20px;">

reaksiyon bölümü doğrudan dengeli denklemin stokiyometrisinden türetilir:

<img alt="Eq3" src="/files/ftp_upload/11691/11691_Equation3.svg" style="text-align: center; height: 44px;">

burada alt simge c ifadede molar konsantrasyonların kullanımını belirtir.

<img alt="Figure2" src="/files/ftp_upload/11691/11691_Figure2.png" style="text-align: center; height: 300px;">

İleri ve geri reaksiyonların hızları eşit olduğunda, reaktant ve ürün türlerinin konsantrasyonları zaman içinde sabit kalır ve sistem dengede olur. Reaksiyonun tersinir doğasını vurgulamak için özel bir çift ok kullanılmıştır.

Bu metin şuradan uyarlanmıştır: <a href="https://openstax.org/books/chemistry-2e/pages/4-3-reaction-stoichiometry">OpenStax Chemistry 2e, Section 4.3: Reaction Stoichiometry</a>; <a href="https://openstax.org/books/chemistry-2e/pages/4-4-reaction-yields">Section 4.4: Reaction Yield</a>; <a href="https://openstax.org/books/chemistry-2e/pages/12-1-chemical-reaction-rates#12163">Section 12.1: Chemical Reaction Rates</a>; <a href="https://openstax.org/books/chemistry-2e/pages/13-1-chemical-equilibria">Section 13.1 Chemical Equilibria</a>, <a href="https://openstax.org/books/chemistry-2e/pages/13-2-equilibrium-constants">Section 13.2 Equilibrium Constants</a><a href="https://openstax.org/books/chemistry-2e/pages/13-2-equilibrium-constants">.</a>

Kimyasal Reaksiyonlar

Dengeli bir kimyasal denklem, kimyasal değişimde yer alan reaktanların ve ürünlerin kimyasal formülleri hakkında bilgi sağlar. A ...

Education

JoVE Core

Organic Chemistry

Organik Kimya

Unit 1

Ünite 1

Thermodynamics and Chemical Kinetics

Termodinamik ve Kimyasal Kinetik

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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 called stoichiometric amounts.

In real reactions, reactants are not always present in the exact amounts shown by the equation. The limiting reactant is the substance that gets used up first. It limits how much product can form. The other substance is the excess reactant. Extra reactant is often added so the other reactant can be fully converted into product.

Water formation is a clear example. The balanced equation shows that 2 moles of hydrogen react with 1 mole of oxygen to make 2 moles of water. This is a 2:1 ratio. If 5 moles of hydrogen and 2 moles of oxygen are available, the ratio is 5:2, or 2.5:1. Hydrogen is then in excess, and oxygen is the limiting reactant. All 2 moles of oxygen use 4 moles of hydrogen, leaving 1 mole of hydrogen unreacted.

Reaction rate is the change in the amount of a reactant or product per unit time. Scientists find reaction rates by measuring how a property changes over time if that property can be linked to reactant or product amounts. A rate graph can show how reactant and product concentrations vary with time.

Some reactions are reversible, which means they can proceed in both the forward and reverse directions. The reaction quotient, Q, helps assess the status of a reversible reaction. It is based on the stoichiometry of the balanced equation, and the subscript c shows that molar concentrations are used in the expression. When the forward and reverse rates are equal, concentrations stay constant and the system is at equilibrium. A double arrow is used to show that the reaction is reversible.

Stoichiometry, Rates, and Equilibrium

chemical reactions

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

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energetics of solution formation

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entropy and solvation

Hydrophobic Effects in Solvation

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gibbs free energy and thermodynamic favorability

gibbs-free-energy-and-thermodynamic-favorability

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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

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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

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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

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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

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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

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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

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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 balanced equations, limiting reactants, reaction rates, and equilibrium help predict product formation and track chemical change in high school chemistry.

Stoichiometry, Rates, and Equilibrium | JoVE K12

organic chemistry

JoVE Core Organik Kimya, kısa ve anlaşılması kolay animasyonlu video dersleri kullanarak stereokimya, reaksiyonlar ve mekanizmaların temel kavramlarını açıklar. Buna ek olarak, bilim insanlarının yer aldığı videolar, ilgili kavramların günümüz laboratuvarlarında gerçekleştirilen klasik ve orijinal araştırma deneylerinde nasıl uygulandığını göstermektedir.

IPC.8.B

Louisiana Student Standards for Science

Chemistry

Matter And Its Interactions

HS-PS1-6

Tennessee Academic Standards

Matter and Its Interactions

CHEM1.PS1.3

CHEM1.PS1.4

Virginia  Standards of Learning

HIgh School

CH.3

CH.3.f

Florida Department of Education

Physical Science

SC.912.P.10

SC.912.P.10.6

SC.912.P.10.12

SC.912.P.12

SC.912.P.12.12

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

C-PS1-6

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Oxidation-Reduction Reactions

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Oxidation Numbers

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Acids, Bases and Neutralization Reactions

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Balancing Redox Equations

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chemical-equilibria-redefining-equilibrium-constant

Chemical Equilibria: Redefining Equilibrium Constant

Recall that the solubility of a sparingly soluble salt increases with the addition of an inert salt in a phenomenon known as the salt effect.
The extent ...

Factors Affecting Activity Coefficient

The activity coefficient of an ion depends on the ionic strength of the solution.
As indicated by the Debye&#8211;H&#252;ckel theory, when the ionic ...

Thermochemical Equations

For a chemical reaction (the system) carried out at constant pressure &ndash; with the only work done caused by expansion or contraction &ndash; the ...

Develop and use models to balance chemical equations and support the claim that atoms, and therefore mass, are conserved during a chemical reaction.

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger ...

Nuclear Power

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Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

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Research and communicate the uses, advantages, and disadvantages of nuclear reactions in current technologies.

IPC.8.C

What is Climate?

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Global Climate Change

Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global ...

Climate Change

The certainty of climate change remains a public controversy despite the consensus among approximately 97% of active climate researchers, who not only ...

Sustainable Development

As the human population continues to grow and use resources, we must be mindful of our planet&rsquo;s natural limits. Sustainable development provides a ...

Construct and communicate an evidence-based explanation of the environmental impact of the end-products of chemical reactions such as those that may result in degradation of water, soil, air quality, and global climate change.

IPC.8.D

Science concepts. The student knows that changes in matter affect everyday life. The student is expected to:

Stoichiometry, Rates, and Equilibrium

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