Name: reading chemical equations and balancing them
Uploaded: 2020-09-03T13:38:26.000Z
Duration: 3 min 10 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

NC K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.4.2

Chemical Equations

تتضمن التفاعلات الكيميائية تحولات كيميائية من مادة أو أكثر إلى مواد مختلفة. يتم تمثيل التفاعل تقليديا باستخدام المعادلة الكيميائية التي تستخدم الصيغ الكيميائية لتمثيل الذرات والجزيئات،أو المركبات المعنية. المواد الموجودة في بداية التفاعل والتي تستهلك أثناء العملية تسمى المتفاعلات.يتم تحديد المتفاعلات في الجانب الأيسر من المعادلة. المواد المتكونة أثناء التفاعل تسمى النواتج وتتضح في الجانب الأيمن من المعادلة. و هناك سهم يفصل بين المواد المتفاعلة والنواتج يوضح اتجاه التفاعل.حالات المادة المختلفة تصور باستخدام الاختصارات بين قوسين. التفاعل الكيميائي يلاحظ قانون حفظ الكتلة،حيث مجموع الكتل لجميع العناصر المشاركة محفوظة. لذلك،العدد التراكمي لذرات كل عنصر سوف تتطابق في كل من المواد المتفاعلة والنواتج.تتم موازنة المعادلات الكيميائية باستخدام المعاملات العددية لتعكس العدد الفعلي للذرات المشاركة في التفاعل. من المهم فقط تغيير المعاملات العددية وليس ذلك الرمز الرقمي الذي يحدد هوية المركب أثناء موازنة أي معادلة كيميائية. تساعد الإرشادات العامة في التوضيح وضبط المعادلة الكيميائية بكفاءة.على سبيل المثال،احتراق سائل حمض البنزويك،و تكوين ثاني أكسيد الكربون الغازي والماء،يمكن تمثيلهم مبدئياًباستخدام معادلة كيميائية هيكلية. يتم موازنة الذرات بعد ذلك عن طريق ضبطها أولاًداخل المركبات تليها ذرات العناصر الحرة. إدراج المعاملات سبعة وثلاثة قبل تركيبات ثاني أكسيد الكربون والماء يوازن ذرات الكربون والهيدروجين.معامل كسري يساوي خمسة عشر في اثنين يضبط ذرات الأكسجين. يتم تحويل المعاملات الكسرية إلى أعداد صحيحة بضرب المعادلة الكاملة في المقام. العدد الجماعي لذرات كل عنصر متساوي في كلا الطرفين في أي معادلة متوازنة.في المعادلات الكيميائية التي تمثل التفاعلات تتضمن المركبات الأيونية،الكاتيونات تتوازن أولا،تليها الأنيونات. دائمًا ما تكون الأيونات متعددة الذرات متوازنة كوحدة. على سبيل المثال،كبريتات الألومنيوم المائية تتفاعل مع هيدروكسيد الكالسيوم المائي لتشكيل هيدروكسيد الألومنيوم الصلب وكبريتات الكالسيوم الصلبة.باستخدام معادلة هيكلية،كاتيونات الألومنيوم والكالسيوم متوازنتان،تليها الأنيونات من هيدروكسيد متعدد الذرات وأيونات الكبريتات. أخيرًا،يتم تعديل المعاملات للحصول على معادلة شاملة متوازنة.

المعادلات الكيميائية

تمثل المعادلات الكيميائية هويات المواد المرتبطة بتفاعل كيميائي وكمياتها النسبية. تسمى المواد التي تخضع للتفاعل المواد المتفاعلة، ويتم وضع صيغتها على الجانب الأيسر من المعادلة. تسمى المواد الناتجة عن التفاعل بالمنتجات، ويتم وضع الصيغ الخاصة بها على الجانب الأيسر من المعادلة. علامات الجمع (+) تفصل بين المادة المتفاعلة وصيغ المنتج الفردية، ويفصل سهم (→) طرفي المادة المتفاعلة والمنتج (الأيسر والأيمن) في المعادلة. يتم تمثيل الأعداد النسبية لأنواع المواد المتفاعلة والمنتجات بمعاملات رقمية، توضع على يسار كل صيغة مباشرة. لا يتم عادةً عرض المُعامِل 1. يتم استخدام أصغر مُعاملات الأعداد الكلية الممكنة بشكل شائع في المعادلة الكيميائية، ويتم تفسيرها كنسب. على سبيل المثال، يتفاعل الميثان والأكسجين مع غاز ثاني أكسيد الكربون الناتج عن انبعاث الماء بنسبة 1:2:1:2.  <img alt="Eq1" src="https://www.jovecore.com/CDNSource/lessons/1019/1019_Equations-01.png" style="height: 40px;" />تشير النسبة إلى أن أصغر مُعاملات الميثان والأكسجين وثاني أكسيد الكربون والماء هي 1، 2، 1، و 1 على التوالي. يمكن تفسير المُعاملات فيما يتعلق بأي وحدة (رقم)، ولذلك قد تتم قراءة هذه المعادلة بشكل صحيح بعدة طرق، بما في ذلك: i. يتفاعل جزيء ميثان وجزيئتا أكسجين للحصول على جزيء ثاني أكسيد الكربون وجزيئتي ماء. ii. يتفاعل مول واحد من جزيئات الميثان و2 مول من جزيئات الأكسجين للحصول على غاز 1 مول من جزيئات ثاني أكسيد الكربون و2 مول من جزيئات الماء.  يشار إلى الحالات الفيزيائية للمواد المتفاعلة والمنتجات في المعادلات الكيميائية في كثير من الأحيان باستخدام اختصار مابين هلالين يتبع الصيغ. تشمل الاختصارات القياسية ‘s’ للمواد الصلبة, ‘l’ للسوائل, ‘g’ للغازات, ‘aq’ للمواد القابلة للانحلال بالماء.<h4>موازنة المعادلات </h4>في المعادلة المتوازنة، تكون أعداد الذرات لكل عنصر مشترك في التفاعل هي نفسها على جوانب المادة المتفاعلة وأطراف المنتج، وبالتالي ترضي قانون حفظ المادة. يمكن تأكيد المعادلة المتوازنة عن طريق جمع أعداد الذرات على أي من جانبي السهم ومقارنة هذه المجاميع للتأكد من أنها متساوية. لاحظ أن عدد الذرات لعنصر معين يتم حسابه عن طريق ضرب معامل أي صيغة تحتوي على هذا العنصر في النص الفرعي للعنصر في الصيغة. إذا ظهر عنصر في أكثر من صيغة على جانب معين من المعادلة، فيجب حساب عدد الذرات الممثلة في كل منها ثم إضافته معاً. لموازنة المعادلة، يمكن تغيير معامِلات المعادلة حسب الحاجة. من الملائم أحيانًا استخدام الكسور بدلاً من الأعداد الصحيحة كمعامِلات وسيطة في عملية موازنة معادلة كيميائية. عند تحقيق التوازن، يمكن بعد ذلك ضرب جميع معاملات المعادلة بعدد صحيح لتحويل المعاملات الكسرية إلى أعداد صحيحة دون الاخلال بالتوازن الذرّي.  على سبيل المثال، ينتج تفاعل الإيثان (C2H6) مع الأكسجين الماء وثاني أكسيد الكربون، والذي يمكن تمثيله بالمعادلة غير المتوازنة التالية: <img alt="Eq2" src="https://www.jovecore.com/CDNSource/lessons/1019/1019_Equations-02.png" style="height: 40px;" />
 تحتوي المعادلة غير المتوازنة على:  <table style="margin-left: auto; margin-right: auto;"><tbody style="border: 1px solid black;"><tr><td style="color: black; border: 1px solid black; text-align: center;">الذرات </td><td style="color: black; border: 1px solid black; text-align: center;">المادة المتفاعلة </td><td style="color: black; border: 1px solid black; text-align: center;">المنتج </td><td style="color: black; border: 1px solid black; text-align: center;"> متوازن؟ </td></tr><tr><td style="color: black; border: 1px solid black; text-align: center;">C </td><td style="color: black; border: 1px solid black; text-align: center;">2 </td><td style="color: black; border: 1px solid black; text-align: center;">1 </td><td style="color: black; border: 1px solid black; text-align: center;">لا </td></tr><tr><td style="color: black; border: 1px solid black; text-align: center;">H </td><td style="color: black; border: 1px solid black; text-align: center;">6 </td><td style="color: black; border: 1px solid black; text-align: center;">2 </td><td style="color: black; border: 1px solid black; text-align: center;">لا </td></tr><tr><td style="color: black; border: 1px solid black; text-align: center;">O </td><td style="color: black; border: 1px solid black; text-align: center;">2 </td><td style="color: black; border: 1px solid black; text-align: center;">3 </td><td style="color: black; border: 1px solid black; text-align: center;">لا </td></tr></tbody></table>لموازنة عدد ذرات الكربون وذرات الهيدروجين، اضرب CO2 في المعامل 2 واضرب H2O في المعامل 3 على التوالي. يؤدي ذلك إلى تغيير إجمالي عدد ذرات الأكسجين على المنتج إلى 7. لموازنة عدد ذرات الأكسجين، اضرب الأكسجين في معامل الكسر 7/2. يعطي هذا التوازن الأولي بين ذرات الكربون والهيدروجين والأكسجين عن طريق تغيير معاملات المواد المتفاعلة والمنتجات المعادلة المتوازنة مؤقتاً:  <img alt="Eq3" src="https://www.jovecore.com/CDNSource/lessons/1019/1019_Equations-03.png" style="height: 40px;" />يتم اشتقاق معادلة تقليدية متوازنة ذات معامِلات أعداد صحيحة فقط عن طريق ضرب كل معامِل في 2، لإنشاء المعادلة: <img alt="Eq4" src="https://www.jovecore.com/CDNSource/lessons/1019/1019_Equations-04.png" style="height: 40px;" />هذا النص مقتبس من <a href="https://openstax.org/books/chemistry-2e/pages/4-1-writing-and-balancing-chemical-equations">Openstax, Chemistry 2e, Section 4.1: Writing and Balancing Chemical Equations</a>.

تمثل المعادلات الكيميائية الهويات والكميات النسبية للمواد المشاركة في التفاعل الكيميائي. المواد التي تخضع للتفاعل هي ...

Education

JoVE Core

الكيمياء

واحد

Molecules, Compounds, and Chemical Equations

الجزيئات والمركبات والمعادلات الكيميائية

molecules-compounds-and-chemical-equations

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

reading chemical equations and balancing them

Chemical equations show the identities and relative amounts of substances in a chemical reaction. The substances that react are called reactants, and their formulas are written on the left side of the equation. The substances formed are called products, and their formulas are written on the right side. A plus sign (+) separates formulas on the same side, and an arrow (→) shows the change from reactants to products.

The numbers in a chemical equation are shown with coefficients. A coefficient is the number written in front of a formula. A coefficient of 1 is usually not written. The smallest whole-number coefficients are commonly used, and they work as ratios. For example, methane and oxygen react to form carbon dioxide and water in a 1:2:1:2 ratio.

That ratio can be read in more than one way. It can mean 1 methane molecule and 2 oxygen molecules make 1 carbon dioxide molecule and 2 water molecules. It can also mean 1 mole of methane molecules and 2 moles of oxygen molecules make 1 mole of carbon dioxide molecules and 2 moles of water molecules. Chemical equations may also include physical states after the formulas. Common state labels are s for solid, l for liquid, g for gas, and aq for substances dissolved in water.

A balanced chemical equation has the same number of atoms for each element on both sides. This follows the law of conservation of matter. To check balance, count the atoms on the reactant side and the product side and compare the totals. To find the number of atoms in a formula, multiply the coefficient by the subscript. If an element appears in more than one formula on one side, add all of those atoms together.

Balancing a chemical equation means changing coefficients, not the formulas themselves. Fractions can be used as temporary coefficients during balancing. For the reaction of ethane with oxygen, carbon and hydrogen are balanced first by placing 2 in front of carbon dioxide and 3 in front of water. That leaves 7 oxygen atoms on the product side, so oxygen gets a fractional coefficient of 7/2. The final equation is then multiplied by 2 to turn all coefficients into whole numbers without changing the balance.

Reading Chemical Equations and Balancing Them

reading-chemical-equations-and-balancing-them

molecules and compounds

Atomic Elements, Molecules, and Bonds

Matter is made of elements, and elements are built from atoms. An atom is the smallest unit of an element that still keeps that element’s properties. A silver coin, for example, is made of silver atoms. Each atom keeps the unique properties of silver. Elements are pure substances made of identical atoms. They cannot be broken down into simpler substances by chemical changes. Most elements are atomic elements, which use single atoms as their basic unit. Carbon and sodium are examples of atomic...

molecular models

Molecular Model Types in Chemistry

Molecular models help chemists and students visualize the structures and shapes of atoms and molecules. They represent the molecular architecture of chemical compounds in a way that is easier to study than formulas alone. Skeletal models are simple two-dimensional drawings of compounds. They show the molecular framework, or the bonds, without drawing every atom. In this model, many carbon and hydrogen atoms are not shown directly. Their positions are implied by the ends and junctions of the...

organic compounds

Organic Molecules in Everyday Chemistry

Organic molecules are carbon-based compounds found in living things and in many everyday products. Most organic compounds have carbon as the main element, bonded to hydrogen and other carbon atoms. Some carbon-containing substances, such as carbonates, cyanides, and simple oxides like CO and CO2, are not classified as organic. Carbon can form up to four strong bonds, which helps explain why organic compounds can make chains and rings of many sizes and shapes. These molecules appear in...

formula mass and mole concepts of compounds

formula-mass-and-mole-concepts-of-compounds

Chemical Formula Mass and Percent Composition

Chemical formula mass and percent composition help describe the makeup of compounds. A chemical formula shows which atoms are present and how many of each atom appear in a substance. For covalent compounds, the formula shows the atoms in one molecule. That is why formula mass can also be called molecular mass. Chloroform, CHCl3, is one example. Its formula shows one carbon atom, one hydrogen atom, and three chlorine atoms. The molecular mass is the sum of their average atomic masses. Ionic...

experimental determination of chemical formula

experimental-determination-of-chemical-formula

Finding Empirical and Molecular Formulas

Chemical formulas show the elemental makeup of a compound. When a formula is unknown, scientists often start by measuring the masses of the elements in the sample. Those mass data are then used to find the simplest whole-number ratio of atoms, which gives the empirical formula. To get from mass to atom ratio, the masses of the elements are first converted to moles using molar masses. Chemical formulas describe numbers of atoms, not masses, so this step is necessary. In one example, 1.71 grams...

chemical equations

Chemical equations show the identities and relative amounts of substances in a chemical reaction. The substances that react are called reactants, and their formulas are written on the left side of the equation. The substances formed are called products, and their formulas are written on the right side. A plus sign (+) separates formulas on the same side, and an arrow (→) shows the change from reactants to products. The numbers in a chemical equation are shown with coefficients. A coefficient...

key terms and concepts

Learn how to read chemical equations, identify reactants and products, use coefficients and state symbols, and balance equations with whole-number ratios.

Reading Chemical Equations and Balancing Them | JoVE K12

chemistry

JoVE Core Chemistry brings general chemistry concepts to life using concise and easy-to-understand animated video lessons. Plus, in the scientist-in-action videos, we demonstrate classical and original research experiments performed in today's laboratories worldwide.

Physical Science

PS.PSc.2.3

Pennsylvania State Academic Standards

Chemical Reactions

3.2.9-12.C

3.2.9-12.G

Louisiana Student Standards for Science

High School

Matter And Its Interactions

HS-PS1-2

HS-PS1-7

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Reactions of matter

Interactions Of Matter

Chemical reactions

Stoichiometry

Tennessee Academic Standards

Matter and Its Interactions

CHEM1.PS1.2

CHEM1.PS1.3

Virginia  Standards of Learning

HIgh School

CH.3

CH.3.a

CH.3.b

CH.3.c

PS.3

PS.3.d

Minnesota Academic Standards in Science

2.2.1 9C.1.2.1.2

Arizona Science Standards

HS+C.P1

HS+C.P1U1.5

HS+C.P1U1.7

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Texas Essential Knowledge and Skills

CHEM.7

CHEM.7.B

CHEM.9

CHEM.9.A

Alabama Course of Study Science

9-12.PS.3.5.d

Next Generation Science Standards

Florida Department of Education

SC.912.P.8

SC.912.P.8.9

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

South Carolina College and Career Ready Science Standards

C-PS1-2

C-PS1-7

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-4.

HS-PS1-7.

HS-PS1-12.

Georgia Standards of Excellence

SPS3.

Chemical Reaction

SC3.

balancing-chemical-equations-and-reaction-outcomes

Balancing Chemical Equations and Reaction Outcomes

Scientific Laws and Theories

Scientific Laws

In science, a law is defined as a concise, verbal or mathematical, statement that summarizes a vast number of experimental observations. ...

The Scientific Method

Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To ...

Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

Classifying Matter by Composition

Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories &mdash; pure substances and ...

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Use models to explain how the scientific understanding of atomic structure has evolved.

PS.Chm.1.1

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

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

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

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

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Use models to compare nuclear reactions including alpha decay, beta decay and gamma decay; nuclear fusion and nuclear fission.

PS.Chm.1.2

Atomic Orbitals

An atomic orbital represents the three-dimensional regions in an atom where an electron has the highest probability to reside. The radial distribution ...

The Pauli Exclusion Principle

The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that ...

The Energies of Atomic Orbitals

In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are ...

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and ...

electron-configuration-of-multielectron-atoms

Electron Configuration of Multielectron Atoms

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the ...

Use models to explain how electrons are distributed in atoms.

PS.Chm.1.3

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Atomic Mass

Atoms &mdash; and the protons, neutrons, and electrons that compose them &mdash; are extremely small. For example, a carbon atom weighs less than 2 ...

Molar Mass

The identity of a substance is defined not only by the types of atoms or ions it contains but by the quantity of each type of atom or ion. For example, ...

Use the Periodic Table as a model to predict the relative properties of elements based on the pattern of valence electrons in the outermost energy levels of atoms.

PS.Chm.2.1

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

Construct an explanation to infer the atomic size, reactivity, electronegativity, and ionization energy of an element based on its position in the Periodic Table.

PS.Chm.2.2

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

trends-in-lattice-energy-ion-size-and-charge

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

bond-polarity-dipole-moment-and-percent-ionic-character

Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

Analyze and interpret data to explain the mechanisms and properties of the two main types of intramolecular (ionic and covalent) bonds.

PS.Chm.3.1

Analyze the structure of atoms and isotopes.

Reading Chemical Equations and Balancing Them

Description

Transcript

More videos by Standards