Name: how energy changes in chemical reactions
Uploaded: 2020-09-03T13:38:27.000Z
Duration: 2 min 27 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

Energy

PS.Chm.7.2

Energy Basics

Почему металлический натрий реагирует с водой с образованием газообразного водорода, а хлорид натрия просто растворяется? Это можно объяснить, изучив взаимосвязь между химией и энергией, называемой термохимией"Все формы материи связаны с энергией, которая может измеряться как тепло или работа. Два основных типа энергии это потенциальная и кинетическая энергия.Потенциальная энергия описывает позиционные силы, действующие на объект. Камень на вершине холма имеет большую потенциальную энергию, чем камень внизу, потому что камень на вершине находится дальше от центра Земли. Кинетическая энергия это энергия движущегося объекта.Если камень столкнуть с холма, он теряет потенциальную энергию, но приобретает кинетическую энергию при движении. Это также относится к атомам или молекулам, из которых состоит объект. Объект в состоянии покоя все еще имеет кинетическую энергию, потому что составляющие его атомы могут колебаться.Эта форма кинетической энергии называется тепловой энергией. Объект имеет более высокую кинетическую энергию и, следовательно, более высокую тепловую энергию, когда атомы движутся более активно. Этот объект ощущается как горячий.Молекулы также обладают потенциальной энергией, называемой химической энергией, которая связана с относительным положением электронов и ядер. Во время реакции химическая энергия преобразуется в другие формы энергии, такие как свет, или энергия выделяется, например, в виде тепла. Количество преобразованной энергии зависит от молекулярной структуры исходных веществ.В газовой лампе ацетилен превращается в углекислый газ и воду, выделяя большое количество энергии в виде света. С другой стороны, добавление гидроксида натрия к соляной кислоте выделяет меньшее количество энергии в виде тепла. Для изучения изменения энергии можно разделить весь мир на систему"которая содержит наблюдаемый процесс, и окружение"то есть все остальное.Система может быть открытой, что означает возможность обмена энергией и веществом между системой и окружающей средой. Система может быть закрытой, где происходит обмен только энергией, также система может быть изолированной, где не происходит обмена ни веществом, ни энергией.

Основы энергетики

Химические реакции, такие как реакции, возникающие при освещении с помощью зажжённой спички, включают в себя изменения в энергии и в материи. 
 
 Химические изменения и сопутствующие им изменения в энергии являются важными элементами повседневной жизни. Макронутриенты в пище подвергаются метаболическим реакциям, которые обеспечивают энергию для поддержания функционирования организма. Различные виды топлива (бензин, природный газ, уголь) сжигаются для производства энергии для транспортировки, отопления и выработки электроэнергии. Промышленные химические реакции используют огромное количество энергии для производства сырья (например, железа и алюминия). Затем энергия используется для производства этих сырьевых материалов в полезные продукты, такие как автомобили, небоскребы и мосты. 
 
 Более 90% энергии, используемой людьми, исходит от солнца. Каждый день солнце обеспечивает землю почти в 10,000 раз больше энергии, необходимой для удовлетворения всех мировых энергетических потребностей на этот день. Остается задача найти способы преобразования и хранения поступающей солнечной энергии, чтобы ее можно было использовать в реакциях или химических процессах, которые одновременно являются удобными и экологически незагрязняющими. Растения и многие бактерии захватывают солнечную энергию посредством фотосинтеза. Люди высвобогают энергию, хранящуюся на заводах, при сжигании древесины, угля, нефти или других продуктов завода, таких как этанол. Они также используют эту энергию для того, чтобы питать свои тела, едя еду, которая поступает непосредственно от растений. 
 
 <h4>Термохимия </h4>
 
 Основные идеи важной области науки, в которой речь идет о количестве тепла, поглощенного или выделяемом в ходе химических и физических изменений, называются термохимическим веществом. Концепции широко используются почти во всех научно-технических областях. Ученые, занимающиеся наукой о пище, используют термохимию для определения энергетического содержания продуктов. Биологи изучают энергетику живых организмов, таких как метаболическое сжигание сахара в углекислый газ и воду. Нефтегазовая и транспортная отрасли, поставщики возобновляемой энергии и многие другие стремятся найти лучшие методы производства энергии для коммерческих и личных нужд. Инженеры стремятся повысить энергоэффективность, найти лучшие способы нагревания и охлаждения домов, охладить продукты питания и напитки, а также удовлетворить энергетические и охлаждающие потребности компьютеров и электроники, в том числе и в других областях применения. Понимание принципов термохимического анализа крайне важно для химиков, физиков, биологов, геологов, инженеров всех типов и практически для всех, кто изучает или занимается какой-либо наукой. 
 
 <h4>Энергии </h4>
 
 Энергия может быть определена как мощность для подачи тепла или работы. Один из видов работы (w) - это процесс, в результате которого материю будет противостоять противоборствующим силам. Например, при накачивании велосипедной шины — вещество перемещается (воздух в насосе) против силы противодействия воздуха, уже поступающего в шину. 
 
 Как и материя, энергия имеет разные типы. Одна схема классифицирует энергию на два типа: Потенциальная энергия, энергия, которую объект имеет из-за его относительного положения, состава или состояния, и кинетическая энергия, энергия, которой обладает объект из-за его движения. 
 
 Вода в верхней части водопада или плотины имеет потенциальную энергию из-за своего положения; когда она течет вниз через генераторы, она обладает кинетической энергией, которая может быть использована для работы и производства электроэнергии на гидроэлектростанции. Аккумуляторная батарея имеет потенциальную энергию, поскольку химические вещества внутри нее могут производить электричество, которое может работать. 
 
 Этот текст был адаптирован из<a href=""https://openstax.org/books/chemistry-2e/pages/5-1-energy-basics""> OpenStax Химия 2е изд., раздел 5.1: Основы энергетики</a>. "

Химические реакции, такие как те, которые происходят, когда вы зажигаете спичку, включают изменения как в энергии, так и в веществе.

Химические изменения и сопровождающие их ...

Education

JoVE Core

Химия

Один

Thermochemistry

Термохимия

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

how energy changes in chemical reactions

Chemical reactions change matter and energy at the same time. A match lighting is a simple example. These energy changes are part of everyday life and appear in food, fuels, and industry.

Food provides energy through metabolic reactions. The macronutrients in food break down and help keep the body functioning. Fuels such as gasoline, natural gas, and coal are burned to produce energy for transportation, heating, and electricity generation.

Industrial chemical reactions also use large amounts of energy. That energy helps make raw materials like iron and aluminum. More energy is then needed to turn those materials into products such as cars, skyscrapers, and bridges.

Most energy used by humans comes from the sun. Every day, the sun sends Earth almost 10,000 times more energy than the world needs for that day. The challenge is to capture and store solar energy so it can drive chemical processes that are useful, convenient, and nonpolluting.

Plants and many bacteria capture solar energy through photosynthesis. Humans release stored energy by burning wood, coal, petroleum, or plant products such as ethanol. They also use this energy directly when they eat food that comes from plants.

Thermochemistry is the study of heat absorbed or released during chemical and physical changes. It is used to measure the energy content of foods and to study the energetics of living organisms, such as the breakdown of sugar into carbon dioxide and water. It also supports work in the oil, gas, transportation, and renewable energy industries, as well as in engineering.

Energy is the capacity to supply heat or do work. Work means causing matter to move against an opposing force, such as when air is pushed into a bicycle tire. Energy can be described as potential energy, which depends on position, composition, or condition, and kinetic energy, which depends on motion.

A waterfall or dam stores potential energy because of its position. When the water flows downward through generators, it has kinetic energy that can do work and produce electricity in a hydroelectric plant. A battery also stores potential energy because the chemicals inside it can produce electricity when needed.

How Energy Changes in Chemical Reactions

energy basics

Chemical reactions change matter and energy at the same time. A match lighting is a simple example. These energy changes are part of everyday life and appear in food, fuels, and industry. Food provides energy through metabolic reactions. The macronutrients in food break down and help keep the body functioning. Fuels such as gasoline, natural gas, and coal are burned to produce energy for transportation, heating, and electricity generation. Industrial chemical reactions also use large amounts...

first law of thermodynamics

Energy Conservation and Internal Energy

Energy conservation describes how energy changes form during chemical and physical changes. Energy can be converted from one form into another, but the energy present before a change still exists in some form after the change is complete. This is the law of conservation of energy. It says energy can neither be created nor destroyed. The law of conservation of matter also applies during chemical change. In most chemical reactions, the total amount of matter does not show a detectable change.

internal energy

Internal Energy, Heat, and Work

Internal energy is the total of all possible kinds of energy in a substance. It is often written as U, and sometimes as E. For a system that changes energy, the important value is the change in internal energy, or ΔU. ΔU is the difference between the final internal energy and the initial internal energy. The exact values of U final and U initial are usually not known, but the first law of thermodynamics only requires ΔU. A positive ΔU means the system gained energy from the surroundings. A...

quantifying heat

Heat Transfer and Specific Heat

Heat transfer and specific heat explain how thermal energy moves and how materials respond to it. Thermal energy is the kinetic energy linked to the random motion of atoms and molecules. Temperature is a measure of how hot or cold a substance is, and it depends on how much thermal energy those particles have. When atoms and molecules move or vibrate faster, their average kinetic energy is higher. That means the object has more thermal energy and a higher temperature. When they move more...

quantifying work

Pressure-Volume Work in Chemistry

Pressure-volume work shows how gas volume changes can transfer energy in chemistry. As a system changes, its internal energy may change too. Energy can move between the system and the surroundings through heat and work. Internal energy, heat, and work are related by an energy equation. Heat depends on a measured temperature change. Work depends on a measured change in volume called pressure-volume work. Work can be defined as a force acting through a distance. Pressure-volume work, also...

enthalpy

Enthalpy and Heat at Constant Pressure

Enthalpy describes heat changes in chemical and physical processes. Chemists use the symbol H for enthalpy. It is defined as a system’s internal energy, E, plus the product of pressure, P, and volume, V. Enthalpy is a state function, so only changes in enthalpy can be measured, not the enthalpy of a substance by itself. For many reactions, the pressure stays constant. Under those conditions, the enthalpy change, ΔH, can be written in a way that includes pressure-volume work. The term PΔV...

thermochemical equations

Heat Changes in Chemical Equations

Heat changes in chemical equations show how much energy a reaction releases or absorbs. At constant pressure, the enthalpy of reaction, or ΔHrxn, is equal to the heat exchanged with the surroundings, qp. Because this value depends on how much reactant takes part, it is an extensive property. The size and sign of ΔHrxn also depend on the reaction itself and on the physical states of the substances involved. An exothermic reaction has a negative ΔHrxn value, while an endothermic reaction has a...

constant pressure calorimetry

Coffee Cup Calorimeter Heat Changes

Coffee cup calorimetry measures heat changes in reactions and physical changes using an insulated calorimeter. The calorimeter is calibrated and designed to limit heat exchange with the outside environment. That makes it possible to measure the heat taken in or released by a substance more accurately, including the energy content of foods. In calorimetry, the system is the substance or substances undergoing change. The surroundings are everything else inside the calorimeter, including the...

constant volume calorimetry

Bomb Calorimeter Heat Measurement

Bomb calorimetry measures the heat released by reactions that produce a lot of energy, especially combustion reactions. A coffee cup calorimeter works at constant pressure and is useful for reactions in solution. A bomb calorimeter works at constant volume and is used for reactions that make large amounts of heat and gaseous products. The word "bomb" refers to the strong, explosive force some reactions can have. In a bomb calorimeter, the volume does not change, so 94V = 0. That means the...

hess's law

Calculating Reaction Heat with Hess's Law

Calculating reaction heat with Hess's law lets chemists find enthalpy changes without measuring every reaction directly. Some reactions are hard or impossible to test in the lab. Even when a reaction can be measured, it is often easier to calculate the heat change from other known enthalpy values. Hess's law says that if a process can be written as the sum of several stepwise processes, the enthalpy change for the total process equals the sum of the enthalpy changes for the steps. This works...

standard enthalpy of formation

Using Standard Enthalpy Values in Chemistry

Enthalpy changes are often listed for reactions that start and end under the same conditions. Chemists use a standard state as a reference set of conditions for comparing properties. In IUPAC terms, the standard state means 1 bar of pressure and 1 M solutions, but it does not set a temperature. Many thermochemical tables still use 1 atm as the reference pressure. Because the difference between 1 bar and 1 atm is very small, enthalpy change usually stays almost the same. A superscripted o in...

enthalpies of reaction

Calculating reaction heat with Hess's law uses standard enthalpies of formation to find the enthalpy change of a reaction. When the formation values for the reactants and products are known, the overall reaction can be broken into simpler stepwise reactions. This approach helps show how the heat change for the full reaction is built from smaller parts. First, the reactants are thought of as being decomposed into their component elements. The enthalpy change for this step is proportional to the...

key terms and concepts

Explore how chemical reactions change energy in food, fuels, photosynthesis, thermochemistry, and batteries. Built for high school science learners.

How Energy Changes in Chemical Reactions | JoVE K12

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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.

Matter and its Interactions

PS.Chm.4.1

Earth and Environmental Science

Earth's Systems

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Physical Science

PS.PSc.7.1

Pennsylvania State Academic Standards

3.2.9-12.O

3.2.9-12.P

3.2.9-12.Q

3.2.9-12.R

Louisiana Student Standards for Science

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Matter And Its Interactions

HS-PS1-4

HS-PS1-5

HS-PS3-2

HS-PS3-3

HS-PS3-4

Physics

HS-PS3-1

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Classification of matter

Energy And Waves

Thermal energy

Interactions Of Matter

Chemical reactions

Physical Geology

Earth's Resources

Energy resources

Tennessee Academic Standards

CHEM1.PS3.3

Virginia  Standards of Learning

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CH.7

CH.7.a

Earth Science

ES.6

ES.6.d

Minnesota Academic Standards in Science

3.1.1 9C.2.2.1.1

Texas Essential Knowledge and Skills

CHEM.13

CHEM.13.A

CHEM.13.C

Alabama Course of Study Science

9-12.PS.1.1

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9-12.ESS.1.1

9-12.ESS.1.1.a

Next Generation Science Standards

Life Science

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South Carolina College and Career Ready Science Standards

Matter and Its Interactions

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P-PS3-1

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P-PS3-3

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Energy

HS-PS3-1.

Georgia Standards of Excellence

SPS7.

Types of Energy

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 ...

physical-and-chemical-properties-of-matter

Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

molecular-comparison-of-gases-liquids-and-solids

Molecular Comparison of Gases, Liquids, and Solids

Particles in a solid are tightly packed together (fixed shape) and often arranged in a regular pattern; in a liquid, they are close together with no ...

Intermolecular vs Intramolecular Forces

Intermolecular forces (IMF) are electrostatic attractions arising from charge-charge interactions between molecules. The strength of the intermolecular ...

Intermolecular Forces

Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions ...

comparing-intermolecular-forces-melting-point-boiling-point

Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility

Intermolecular forces are attractive forces that exist between molecules. They dictate several bulk properties, such as melting points, boiling points, ...

surface-tension-capillary-action-and-viscosity

Surface Tension, Capillary Action, and Viscosity

Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded ...

States of Matter and Phase Changes

The internal energy of a substance&#8212;the total kinetic energy of all its molecules and the potential energy of their associated forces&#8212;depends ...

Phase Transitions

Whether solid, liquid, or gas, a substance&#39;s state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the ...

phase-transitions-vaporization-and-condensation

Phase Transitions: Vaporization and Condensation

The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize ...

Vapor Pressure

When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules move randomly about, they will occasionally ...

Clausius-Clapeyron Equation

The equilibrium between a liquid and its vapor depends on the temperature of the system; a rise in temperature causes a corresponding rise in the vapor ...

Phase Transitions: Melting and Freezing

Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy ...

phase-transitions-sublimation-and-deposition

Phase Transitions: Sublimation and Deposition

Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and ...

Heating and Cooling Curves

When a substance&#8212;isolated from its environment&#8212;is subjected to heat changes, corresponding changes in temperature and phase of the substance ...

Phase Diagrams

A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. ...

Use models to explain how changes in energy affect the arrangement and movement of the particles in solids, liquids, and gases, as well as the relative strengths of their intermolecular forces.

PS.Chm.7.1

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.

Chemical changes and their accompanying ...

First Law of Thermodynamics

Energy Conservation

Energy can be converted from one form into another, but all of the energy present before a change occurs always exists in some form ...

Internal Energy

The total of all possible kinds of energy present in a substance is called the internal energy (U), sometimes symbolized as E. Suppose a system with ...

Quantifying Heat

Thermal Energy&#160;

Microscopically, thermal energy is the kinetic energy associated with the random motion of atoms and molecules. Temperature is a ...

Quantifying Work

As a system undergoes a change, its internal energy can change, and energy can be transferred from the system to the surroundings, or from the ...

Enthalpy

Chemists ordinarily use a property known as enthalpy (H) to describe the thermodynamics of chemical and physical processes. Enthalpy is defined as the sum ...

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 ...

Constant Pressure Calorimetry

Calorimetry is a technique used to measure the amount of heat involved in a chemical or physical process or to measure the heat transferred to or from a ...

Constant Volume Calorimetry

Calorimeters are useful to determine the heat released or absorbed by a chemical reaction. Coffee cup calorimeters are designed to operate at constant ...

Use mathematics and computational thinking to execute simple calorimetric calculations based on the Law of Conservation of Energy.

Understand the relationship among pressure, temperature, volume, and phase.

How Energy Changes in Chemical Reactions

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