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

Waarom reageert natriummetaal met water om waterstofgas te maken, maar lost natriumchloride gewoon op? Dit kan worden verklaard door de relatie tussen chemie en energie te bestuderen, genaamd thermochemie'Alle vormen van materie worden geassocieerd met energie, die kan worden gemeten als warmte of arbeid. De twee belangrijkste soorten energie zijn potentiële en kinetische energie.Potentiële energie beschrijft de positionele krachten die op het object inwerken. Een rots op de top van een heuvel heeft meer potentiële energie dan een rots onderaan, omdat de rots bovenaan zich verder van het massamiddelpunt van de aarde bevindt. Kinetische energie is de energie van een bewegend object.Als een rots van de heuvel wordt geduwd, verliest hij potentiële energie, maar krijgt hij kinetische energie terwijl hij beweegt. Dit geldt ook voor de atomen of moleculen waaruit een object bestaat. Een object in rust heeft nog kinetische energie omdat de samenstellende atomen kunnen trillen.Deze vorm van kinetische energie wordt thermische energie genoemd. Een object heeft een hogere kinetische energie en daardoor hogere thermische energie wanneer de atomen krachtiger bewegen. Dit object wordt als heet ervaren.Moleculen hebben ook potentiële energie, chemische energie genaamd, die wordt geassocieerd met de relatieve positie van elektronen en kernen. Tijdens een reactie wordt chemische energie omgezet in andere vormen van energie, zoals licht, of komt er energie vrij, zoals in de vorm van warmte. De hoeveelheid getransformeerde energie hangt af van de moleculaire structuur van reactanten.In een gaslamp brandt acetyleen in kooldioxide en water, waardoor een grote hoeveelheid energie als licht vrijkomt. Aan de andere kant geeft het toevoegen van natriumhydroxide aan zoutzuur een kleinere hoeveelheid energie vrij, als warmte. Om energieveranderingen te bestuderen, helpt het om het universum te verdelen in een systeem'dat het waargenomen proces bevat, en de omgeving'dat al het andere is.Het systeem kan open zijn, wat betekent dat zowel energie als massa kan worden uitgewisseld tussen het systeem en de omgeving. Het systeem kan gesloten zijn, waarbij alleen energie wordt uitgewisseld, of het systeem kan geïsoleerd zijn, waar geen massa of energie worden uitgewisseld.

basisprincipes van energie

Chemische reacties, zoals die optreden wanneer je een lucifer aansteekt, brengen veranderingen in energie en materie met zich mee. Chemische reacties en de daarmee gepaard gaande veranderingen in energie zijn belangrijke onderdelen van het dagelijks leven. De macronutriënten in voedsel ondergaan metabolische reacties die de energie leveren om het lichaam te laten functioneren. Er wordt een verscheidenheid aan brandstoffen (benzine, aardgas, steenkool) verbrand om energie te produceren voor transport, verwarming en de opwekking van elektriciteit. Industriële chemische reacties gebruiken enorme hoeveelheden energie om grondstoffen (zoals ijzer en aluminium) te produceren. Energie wordt vervolgens gebruikt om die grondstoffen te vervaardigen tot nuttige producten, zoals auto's, wolkenkrabbers en bruggen. Ruim 90% van de energie die de mens gebruikt, komt oorspronkelijk van de zon. Elke dag voorziet de zon de aarde van bijna 10.000 keer de hoeveelheid energie die nodig is om voor die dag in alle energiebehoeften van de wereld te voorzien. De uitdaging blijft manieren vinden om binnenkomende zonne-energie om te zetten en op te slaan, zodat deze kan worden gebruikt in reacties of chemische processen die zowel handig als niet-vervuilend zijn. Planten en veel bacteriën vangen zonne-energie op via fotosynthese. Mensen maken de energie vrij die in planten is opgeslagen bij het verbranden van hout, steenkool, aardolie of andere plantaardige producten zoals ethanol. Ze gebruiken deze energie ook om hun lichaam van brandstof te voorzien door voedsel te eten dat rechtstreeks van planten komt. <h4>Thermochemie</h4> De basisideeën van een belangrijk wetenschapsgebied dat zich bezighoudt met de hoeveelheid warmte die wordt geabsorbeerd of vrijgegeven tijdens chemische en physical processes, wordt thermochemie genoemd. De concepten worden op vrijwel alle wetenschappelijke en technische terreinen veel gebruikt. Voedingswetenschappers gebruiken thermochemie om de energie-inhoud van voedingsmiddelen te bepalen. Biologen bestuderen de energieën van levende organismen, zoals de metabolische verbranding van suiker in kooldioxide en water. De olie-, gas- en transportindustrieën, leveranciers van hernieuwbare energie en vele anderen proberen betere methoden te vinden om energie te produceren voor commerciële en persoonlijke behoeften. Ingenieurs streven ernaar de energie-efficiëntie te verbeteren, betere manieren te vinden om huizen te verwarmen en te koelen, voedsel en dranken te koelen en te voldoen aan de energie- en koelingsbehoeften van onder meer computers en elektronica. Het begrijpen van thermochemische principes is essentieel voor scheikundigen, natuurkundigen, biologen, geologen, elk type ingenieur en vrijwel iedereen die enige vorm van wetenschap studeert of doet. <h4>Energie</h4> Energie kan worden gedefinieerd als het vermogen om warmte te leveren of arbeid te verrichten. Eén type werk (w) is het proces waarbij materie tegen een tegengestelde kracht in beweegt. Bij het oppompen van bijvoorbeeld een fietsband wordt materie verplaatst (de lucht in de pomp) tegen de tegengestelde kracht in van de lucht die zich al in de band bevindt. Net als materie bestaat energie in verschillende soorten. Eén schema classificeert energie in twee typen: potentiële energie, de energie die een object heeft vanwege zijn relatieve positie, samenstelling of toestand, en kinetische energie, de energie die een object bezit vanwege zijn beweging. Water op de top van een waterval of dam heeft potentiële energie vanwege zijn positie; wanneer het door generatoren naar beneden vloeit, heeft het kinetische energie die kan worden gebruikt om werk te doen en elektriciteit te produceren in een waterkrachtcentrale. Een batterij heeft potentiële energie omdat de chemicaliën erin elektriciteit kunnen produceren die werk kan doen.

Basisprincipes van energie

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 ...

Education

JoVE Core

Scheikunde

Eén

Thermochemistry

Thermochemie

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

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

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.

Matter and its Interactions

PS.Chm.4.1

Earth and Environmental Science

Earth's Systems

ESS.EES.3.2

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

High School

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

HIgh School

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

Earth and Space Science

Earth's Place in the Universe

9-12.ESS.1.1

9-12.ESS.1.1.a

Next Generation Science Standards

Life Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-7

Florida Department of Education

SC.912.E.6

SC.912.E.6.6

SC.912.P.10

SC.912.P.10.1

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

South Carolina College and Career Ready Science Standards

Matter and Its Interactions

C-PS1-4

C-PS1-5

C-PS3-4

P-PS3-1

P-PS3-2

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

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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