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

화학 반응은 하나 이상의 물질이 다른 물질로 화학적으로 변환하는 과정을 포함합니다. 반응은 일반적으로 화학 방정식을 사용하여 표현되는 데 방정식에서는 화학식을 활용하여 포함되는 원자, 분자 또는 화합물을 표현합니다. 반응을 시작할 때 존재하지만 반응 과정에 소비되는 물질을 반응물이라고 합니다.

반응물은 방정식의 왼쪽에 자리합니다. 반응 중에 형성된 물질을 생성물이라고 하며 방정식의 오른쪽에 표시됩니다. 반응물과 생성물을 구분하는 화살표는 반응 방향을 나타냅니다.

물질의 다양한 상태는 괄호 안의 약어를 사용하여 서술합니다. 화학 반응에서는 질량보존 법칙이 적용되며 따라서 반응에 참여한 모든 원소들의 총 질량이 보존됩니다. 따라서 각 원소의 누적 원자 수는 반응물과 생성물 모두에서 일치합니다.

화학 방정식은 반응에 포함되는 실제 원자의 수를 반영하는 계수를 적용하여 균형을 맞춥니다. 화합물의 조성을 정의하는 숫자 첨자가 아니라 숫자 계수만 변경하여 화학 방정식의 균형을 맞추는 것이 중요합니다. 일반적인 지침을 통해 화학 방정식을 효율적으로 설명하고 조정할 수 있습니다.

예를 들어 액체 벤조산이 연소하여 기체 상태의 이산화탄소 및 물이 형성되는 반응을 우선 골격 화학 방정식을 사용하여 표현할 수 있습니다. 먼저 화합물 내의 원자 수를 맞추고 그 다음에 단일 원소의 원자수를 조정함으로써 원자의 균형을 맞춥니다. 이산화탄소와 물의 화학식에 앞서 계수 7과 3을 포함하여 탄소 원자와 수소 원자의 균형을 이룹니다.

15x2의 분할 계수를 통해 산소 원자를 조절합니다. 분할 계수는 기본 방정식에 분모값을 곱하여 정수로 변환됩니다. 각 원소의 원자의 수의 합은 균형 방정식의 양쪽에서 동일합니다.

이온 화합물을 포함하는 반응을 나타내는 화학 방정식에서 양이온의 균형을 먼저 맞추고 그 다음 음이온의 균형을 맞춥니다. 다원자 이온은 항상 하나의 유닛으로 균형이 보장됩니다. 예를 들어 수성 황산 알루미늄은 수성 수산화칼슘과 반응하여 고체 상태의 수산화알루미늄과 황산칼슘을 생성합니다.

골격 방정식을 사용하여 알루미늄과 칼슘의 양이온의 균형을 맞추고 다음 다원자 수산화물과 황산염 이온의 음이온의 균형을 고려합니다. 마지막으로 계수를 조정하여 전체 균형 방정식을 얻습니다.

화학 반응식

화학 반응식은 화학 반응에 관련된 물질의 정체와 상대적인 양을 나타냅니다. 반응을 일으키는 물질을 반응물이라고 하며, 그 반응식은 방정식의 왼쪽에 표시합니다. 반응에 의해 생성된 물질을 생성물이라고 하며, 그 공식은 방정식의 오른쪽에 표시됩니다. 더하기 기호(+)는 개별 반응물과 생성물 공식을 구분하고, 화살표(→)는 방정식의 반응물과 생성물(왼쪽 및 오른쪽)을 구분합니다. 반응물과 생성물 종의 상대적인 수는 각 공식의 바로 왼쪽에 배치된 수치 계수로 표시됩니다. 일반적으로 계수 1은 표시되지 않습니다. 가능한 가장 작은 정수 계수는 일반적으로 화학 반응식에서 사용되며 비율로 해석됩니다. 예를 들어, 메탄과 산소가 반응하여 1:2:1:2 비율로 이산화탄소와 물을 생성합니다.

<img alt="Eq1" src="https://www.jove.com/files/core/CDNSource/lessons/1019/1019_Equations-01.png" style="height: 40px;" />

이 비율은 메탄, 산소, 이산화탄소, 물의 가능한 가장 작은 계수가 각각 1, 2, 1, 2임을 나타냅니다. 계수는 임의의 양(수) 단위로 해석될 수 있으므로 이 방정식은 다음을 포함하여 다양한 방법으로 올바르게 해석될 수 있습니다.

i. 메탄 분자 1개와 산소 분자 2개가 반응하여 이산화탄소 분자 1개와 물 분자 2개가 생성됩니다.

ii. 메탄 분자 1몰과 산소 분자 2몰이 반응하여 이산화탄소 분자 1몰과 물 분자 2몰이 생성됩니다.

화학 방정식에서 반응물과 생성물의 물리적 상태는 공식 뒤에 괄호로 묶은 약어로 표시되는 경우가 많습니다. 표준 약어에는 고체의 경우 's', 액체의 경우 'l', 기체의 경우 'g', 물에 용해되는 물질의 경우 'aq'가 포함됩니다.

균형 방정식

균형 반응식에서는 반응에 참여하는 각 원소의 원자 수가 반응물 측과 생성물 측에서 동일하므로 물질 보존의 법칙을 만족합니다. 균형 잡힌 방정식은 화살표 양쪽에 원자 수를 더하고 이 합을 비교하여 동일한지 확인함으로써 확인할 수 있습니다. 특정 원소의 원자 수는 해당 원소를 포함하는 공식의 계수에 해당 원소의 첨자를 곱하여 계산됩니다. 방정식의 특정 측면에서 원소가 두 개 이상의 공식에 나타나는 경우, 각각에 표시된 원자 수를 계산한 다음 함께 더해야 합니다.

방정식의 균형을 맞추기 위해 방정식의 계수는 필요에 따라 변경될 수 있습니다. 화학 방정식의 균형을 맞추는 과정에서 중간 계수로 정수 대신 분수를 사용하는 것이 편리한 경우가 있습니다. 균형이 이루어지면 모든 방정식의 계수에 정수를 곱하여 원자 균형을 깨뜨리지 않고 분수 계수를 정수로 변환할 수 있습니다.

예를 들어, 에탄(C_2H_6)과 산소의 반응으로 물과 이산화탄소가 생성되며 이는 다음 불균형 방정식으로 표현될 수 있습니다.

<img alt="Eq2" src="https://www.jove.com/files/core/CDNSource/lessons/1019/1019_Equations-02.png" style="height: 40px;" />

불균형 방정식에는 다음이 포함됩니다.

<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;">원자</td>
			<td style="color: black; border: 1px solid black; text-align: center;">반응물</td>
			<td style="color: black; border: 1px solid black; text-align: center;">제품</td>
			<td style="color: black; border: 1px solid black; text-align: center;">균형?</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;">아니요</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;">아니요</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;">아니요</td>
		</tr>
	</tbody>
</table>

탄소 원자와 수소 원자 수의 균형을 맞추려면 CO_2에 계수 2를 곱하고 H_2O에 계수 3을 곱합니다. 이렇게 하면 제품의 총 산소 원자 수가 7로 변경됩니다. 산소 원자 수의 균형을 맞추려면 산소에 분수 계수 7/2를 곱합니다. 반응물과 생성물의 계수를 변경하여 탄소, 수소 및 산소 원자의 초기 균형을 맞추면 잠정 균형 방정식이 제공됩니다.

<img alt="Eq3" src="https://www.jove.com/files/core/CDNSource/lessons/1019/1019_Equations-03.png" style="height: 40px;" />

정수로만 구성된 계수를 사용하는 기존의 균형 방정식은 각 계수에 2를 곱하여 방정식을 생성하여 도출됩니다.

<img alt="Eq4" src="https://www.jove.com/files/core/CDNSource/lessons/1019/1019_Equations-04.png" style="height: 40px;" />

이 문서는 에서 발췌되었습니다 <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>.

화학 방정식은 화학 반응에 관련된 물질의 정체와 상대적인 양을 나타냅니다. 반응을 겪고 있는 물질은 ...

Education

교육

JoVE Core

화학

하나

Molecules, Compounds, and Chemical Equations

분자, 화합물 및 화학 방정식

molecules-compounds-and-chemical-equations

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 화학은 간결하고 이해하기 쉬운 애니메이션을 통해 일반 화학 개념을 설명합니다. 또한, 과학자가 직접 고전실험과 연구실험을 진행하는 실사 영상을 제공합니다.

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

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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 ...

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

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