Name: gibbs free energy and reaction work
Uploaded: 2023-04-30T10:08:58.000Z
Duration: 1 min 5 s
Channel: JoVE

K12 Standards

Minnesota Academic Standards in Science

9-12

Chemistry

3.1.1 9C.2.2.1.1

An Introduction to Free Energy

Gibbs free energy is the energy available for a system to perform work at a constant temperature and pressure. The change in free energy, or &#8710;G, can be used to predict a reaction&#39;s spontaneity.
Spontaneous processes increase the entropy of the universe; however, it is difficult to measure this entropy change because it includes changes in the disorder of the system being studied and its surroundings.
Using the equation for Gibbs&#39;s free energy, spontaneity can be determined by the enthalpy and entropy change of the system alone.
If the system releases heat, the surroundings absorb the heat, which influences the randomness of the surroundings. Mathematically, the entropy of the surroundings equals the negative enthalpy change of the system divided by the temperature.
Rearranging the Gibbs equation shows the negative ratio of free energy change and temperature is equal to the entropy change of the universe.

an introduction to free energy

How can we compare the energy that releases from one reaction to that of another reaction? We use a measurement of free energy to quantitate these energy transfers. Scientists call this free energy Gibbs free energy (abbreviated with the letter G) after Josiah Willard Gibbs, the scientist who developed the measurement. According to the second law of thermodynamics, all energy transfers involve losing some energy in an unusable form such as heat, resulting in entropy. Gibbs free energy specifically refers to the energy of a chemical reaction that is available after we account for entropy. In other words, Gibbs free energy is usable energy, or energy that is available to do work.
Every chemical reaction involves a change in free energy, called delta G (&#8710;G). We can calculate the change in free energy for any system that undergoes such a change, such as a chemical reaction. To calculate &#8710;G, subtract the amount of energy lost to entropy (denoted as &#8710;S) from the system&#39;s total energy change. The total energy in the system is enthalpy and we denote it as &#8710;H. The formula for calculating &#8710;G is as follows, where the symbol T refers to the absolute temperature in Kelvin (degrees Celsius + 273):
&#916;G = &#916;H &#8722; T&#916;S
We express a chemical reaction&#39;s standard free energy change as an amount of energy per mole of the reaction product (either in kilojoules or kilocalories, kJ/mol or kcal/mol; 1 kJ = 0.239 kcal) under standard pH, temperature, and pressure conditions. We generally calculate standard pH, temperature, and pressure conditions at pH 7.0 in biological systems, 25 degrees Celsius, and 100 kilopascals (1 atm pressure), respectively. Note that cellular conditions vary considerably from these standard conditions, and so standard calculated &#8710;G values for biological reactions will be different inside the cell.
This text is adapted from Openstax, Biology 2e, <a href="https://openstax.org/books/biology-2e/pages/6-2-potential-kinetic-free-and-activation-energy">Section 6.2: </a><a href="https://openstax.org/books/biology-2e/pages/6-2-potential-kinetic-free-and-activation-energy">Potential, Kinetic, Free, and Activation Energy</a> and Openstax, Chemistry 2e, <a href="https://openstax.org/books/chemistry-2e/pages/16-4-free-energy?query=free%20energy&amp;target=%7B%22index%22%3A0%2C%22type%22%3A%22search%22%7D#fs-idm21370272">Section 16.4: Free Energy</a>.

How can we compare the energy that releases from one reaction to that of another reaction? We use a measurement of free energy to quantitate these energy ...

Education

JoVE Core

Cell Biology

Unit 1

Energy and Catalysis

KEY TERMS AND CONCEPTS

gibbs free energy and reaction work

Gibbs free energy describes the usable energy in a chemical reaction. It helps scientists compare how much energy different reactions release. This measurement is called Gibbs free energy, or G, after Josiah Willard Gibbs.

The second law of thermodynamics explains why not all energy stays available for work. Some energy is lost in an unusable form, such as heat, and this loss increases entropy. Gibbs free energy is the energy left after that entropy loss is taken into account.

Every chemical reaction has a change in free energy, written as delta G. Scientists can calculate delta G for any system that changes, including a chemical reaction. The equation is delta G = delta H − T delta S, where delta H is the total energy change, delta S is the energy lost to entropy, and T is the absolute temperature in Kelvin.

Standard free energy change is reported as energy per mole of product. It is usually given in kilojoules per mole or kilocalories per mole. Standard conditions use pH 7.0 in biological systems, 25 degrees Celsius, and 100 kilopascals, which is about 1 atm of pressure.

These standard values are useful for comparison, but cell conditions are not the same. Because the inside of a cell can differ a lot from standard conditions, the calculated delta G for a biological reaction can also be different inside the cell.

Gibbs Free Energy and Reaction Work

the first law of thermodynamics

Energy Changes in Cells and Matter

The first law of thermodynamics describes how energy changes form in the universe. The total amount of energy stays constant. Energy can move from one place to another or change into a different form, but it cannot be created or destroyed. These energy changes happen in everyday life. A light bulb changes electrical energy into light energy. A gas stove changes chemical energy in natural gas into heat energy. Plants also carry out a major energy transformation when they convert sunlight energy...

the second law of thermodynamics

Entropy and Spontaneous Change

Entropy helps predict whether a process will happen on its own. Entropy is a measure of randomness or disorder in a system. High entropy means high disorder and low energy. A student’s bedroom is a simple example. If no work is done, the room becomes messy over time. That messy state is highly disordered and has high entropy. To make the room clean again, energy must be added as the student puts things away. That organized state has low entropy. Processes that increase the entropy of the...

enthalpy within the cell

Cellular Enthalpy and Energy Changes

Cellular enthalpy describes how heat and energy change during chemical and physical processes. Enthalpy is written as H and is defined as the sum of a system’s internal energy, U, and the product of pressure and volume, PV. It is a state function, which means its value depends on the state of the system, not the path taken. Scientists cannot measure the enthalpy of a single substance directly. They can determine enthalpy changes, or ΔH, for a process instead. For reactions or changes that...

entropy within the cell

Cell Energy Loss and Entropy

Cell energy loss and entropy explain why living things need constant energy input. Cells obtain energy, transform it, and use it to do work, but these transfers are never completely efficient. In each transfer, some energy is lost in a form that cannot be used. In many cases, that lost energy is heat energy.

Gibbs free energy describes the usable energy in a chemical reaction. It helps scientists compare how much energy different reactions release. This measurement is called Gibbs free energy, or G, after Josiah Willard Gibbs. The second law of thermodynamics explains why not all energy stays available for work. Some energy is lost in an unusable form, such as heat, and this loss increases entropy. Gibbs free energy is the energy left after that entropy loss is taken into account. Every chemical...

endergonic and exergonic reactions in the cell

endergonic-and-exergonic-reactions-in-the-cell

Cell Reactions That Release or Store Energy

Cell reactions can either release energy or store it for later use. In chemistry, this difference is described by the value of ΔG, or free energy change. When energy is released during a reaction, ΔG is negative. The products then have less free energy than the reactants because some free energy has been given off. Reactions with a negative ΔG are called exergonic reactions. Exergonic means energy is leaving the system. These reactions are also called spontaneous reactions because they can...

the equilibrium binding constant and binding strength

the-equilibrium-binding-constant-and-binding-strength

How Equilibrium Binding Constant Affects Binding

The equilibrium binding constant describes how strongly two molecules bind at equilibrium. It is a useful way to compare binding strength in molecular interactions. This topic focuses on how binding is measured and what the equilibrium binding constant means. A higher value indicates stronger binding, while a lower value indicates weaker binding. Understanding this constant helps explain how tightly molecules stay together under equilibrium conditions. The page also connects the binding...

free energy and equilibrium

Free Energy and Reaction Direction

Free energy and reaction direction are linked in chemical equilibrium. A free energy change, ΔG, shows the driving force for a process. When ΔG is negative, the process is driven forward. When ΔG is positive, the reverse direction is favored. When ΔG is zero, the forward and reverse driving forces are equal, and the system is at equilibrium. The reaction quotient, Q, helps show how close a system is to equilibrium. Q is the numerical value of the mass action expression for the system. It can...

non-equilibrium in the cell

Cells Stay Out of Equilibrium

Cells stay out of chemical equilibrium by constantly using energy and moving materials in and out. Chemical reactions in metabolism are often reversible. They can go in both directions. In one direction, they release energy to the surroundings. In the reverse direction, they absorb energy. The same idea applies to reactions that build and break down cell molecules. Proteins, for example, can be broken into individual amino acids, and amino acids can be used to build proteins again. In a closed...

oxidation and reduction of organic molecules

oxidation-and-reduction-of-organic-molecules

Electron Carriers in Cell Energy Transfer

Cell energy production depends on redox reactions, which are oxidation and reduction reactions that happen together. In oxidation, an electron is removed from an atom in a compound. In reduction, that same electron is added to another compound. Because these reactions usually occur as a pair, they are called redox reactions. When a molecule loses an electron, its potential energy goes down. The electron does not stay free in the cytoplasm. Instead, it moves to a second compound and reduces...

introduction to enzymes

Enzyme Function, Cofactors, and Inhibitors

Enzymes are proteins that speed up biochemical reactions without being used up. Humans have used enzymes since about 7000 BCE, when they fermented sugars to make alcohol without knowing the reaction was enzyme-catalyzed. The word enzyme was coined by Wilhelm Kuhne in 1877. It comes from the Greek words en, meaning “in” or “within,” and zyme, meaning “yeast.” Enzymes work through active sites, which are regions that bind substrates and help convert them into products. Many enzymes also have...

enzymes and activation energy

How Enzymes Lower Reaction Energy

Enzymes lower the energy needed for a chemical reaction to begin. That starting energy is called activation energy, or free energy of activation, and it is often written as Ea. During a reaction, bonds break and new bonds form. In glucose breakdown, for example, bonds between carbon atoms break and release energy because they are energy-storing bonds. Before a reaction can move forward, reactant molecules must reach a high-energy, unstable shape called the transition state. To get there, the...

introduction to enzyme kinetics

Graphing Enzyme Kinetics Data

Enzyme kinetics uses graphs to show how fast a biochemical reaction happens. Scientists measure the initial reaction rate, or velocity (Vo), at different substrate concentrations ([S]). They may also run trials with inhibitors or other molecules that change the reaction rate. The results are often plotted as Vo against [S]. For many single-substrate reactions, the data fits the Michaelis-Menten equation. This equation, named after Leonor Michaelis and Maud Menten, helps estimate the maximum...

turnover number and catalytic efficiency

How Fast Enzymes Work in Digestion

Enzymes can work at very different speeds, and their turnover number shows how fast they convert substrate molecules into products. Turnover number is the maximum number of substrate molecules an enzyme can transform per unit time. For most enzymes, this value is between 1 and 1000 molecules per second. Some enzymes are especially fast. Catalase has the highest known turnover number and can convert up to 2.8×10^6 molecules of hydrogen peroxide into water and oxygen each second. Lysozyme has...

catalytically perfect enzymes

Diffusion-Controlled Enzymes and Reaction Speed

Catalytically perfect enzymes are enzymes that speed up biochemical reactions at very high rates. The idea was first proposed by W. J. Albery and J. R. Knowles in 1976. These enzymes have catalytic efficiency values of about 10^8 to 10^9 M^-1 s^-1 and are also called diffusion-controlled enzymes because diffusion of the substrate into the active site is the only rate-limiting step. Examples of catalytically perfect enzymes include triose phosphate isomerase, fumarase, and superoxide dismutase.

introduction to mechanisms of enzyme catalysis

introduction-to-mechanisms-of-enzyme-catalysis

How Enzymes Change Shape to Catalyze

Enzyme catalysis depends on how enzymes bind substrates and how the active site responds during the reaction. Scientists once described this process with a simple lock-and-key model, where the enzyme and substrate fit together in one instant. Research now supports induced fit, a more dynamic model in which binding causes a small change in the enzyme’s shape. That shift helps create an ideal match between the enzyme and the substrate’s transition state, which improves catalysis. The active site...

ligand binding and linkage

Ligand Binding and Allosteric Effects

Ligand binding and linkage describe how one molecule can affect another when it binds to a protein. In this topic, the focus is on how binding at one site can influence activity at a different site on the same protein. This idea is important for understanding protein function in high school biology. It helps explain why some proteins respond more strongly after a ligand attaches. The transcript centers on the connection between ligand binding and linkage, which is a key concept in molecular...

cooperative allosteric transitions

How Proteins Shift Shape Together

Proteins can change shape in a coordinated way during allosteric transitions. In a cooperative transition, one part of the protein affects another part, so the change spreads through the molecule. These shape changes help proteins switch between different states. The shift can influence how the protein works and how it responds to other molecules. Cooperative allosteric transitions are an important idea in protein function. They explain how a small change at one site can lead to a larger...

ribozymes

Catalytic RNA: Ribozymes in Action

Ribozymes are RNA molecules that can act as enzymes. They help speed up specific chemical reactions without being protein enzymes. This makes them an important example of RNA with more than one job in the cell. Some ribozymes can cut RNA molecules, and others can join them together. This shows that RNA can do catalytic work as well as carry genetic information. Ribozymes are a key part of how scientists think about the many roles of RNA in biology. One well-known ribozyme is ribonuclease P,...

atp energy storage and release

ATP Powers Cellular Transport and Reactions

ATP powers cellular transport and many reactions by transferring energy through phosphorylation. ATP is a highly unstable molecule. If it is not used quickly, it breaks down into ADP and inorganic phosphate, and the released energy is lost as heat. Cells use ATP through energy coupling. This means the exergonic reaction of ATP hydrolysis is linked to an endergonic reaction so the reaction can move forward. One major example is the sodium-potassium pump, a transmembrane ion pump that is vital...

atp and macromolecule synthesis

ATP in Building Cell Macromolecules

ATP helps cells build biological macromolecules. These organic compounds are mainly made of carbon atoms bonded to hydrogen, oxygen, nitrogen, and small amounts of other elements. The four major classes of biological macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Most macromolecules start as small subunits called monomers. Cells join monomers with covalent bonds to make larger molecules called polymers. This building process needs energy, so cells depend on ATP, the...

coupled reactions

ATP Powers Cellular Work

ATP powers many kinds of cellular work by coupling energy-releasing reactions to energy-requiring ones. Some reactions happen on their own and release energy. Others need an energy input to move forward. Cells link these reactions so important processes can still occur. Adenosine triphosphate, or ATP, stores energy that cells can use quickly. ATP hydrolysis is the breaking of ATP, and it releases energy. Cells often use that released energy to drive endergonic reactions, which are reactions...

key terms and concepts

Learn how Gibbs free energy measures usable energy in reactions, how delta G is calculated, and why standard conditions can differ from cell conditions.

Gibbs Free Energy and Reaction Work | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

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

South Carolina College and Career Ready Science Standards

High School

Energy

C-PS3-4

Physics

P-PS3-3

Periodic Classification of the Elements

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Electron Configuration of Multielectron Atoms

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VSEPR Theory and the Basic Shapes

Overview of VSEPR Theory

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Predicting Molecular Geometry

VSEPR Theory for Determination of Electron Pair Geometries

The following procedure uses VSEPR theory to determine the electron pair geometries and the ...

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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 ...

Matter and Its Interactions: Analyze patterns in air or water quality data to make claims about the causes and severity of a problem and the necessity to remediate or to recommend a treatment process. (P: 4, CC :2, CI: PS1)

9C.2.1.1.1

Energy Transfer in Chemical Reactions

Chemical reactions require sufficient energy to cause the matter to collide with enough precision and force that old chemical bonds can be broken and new ...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

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Bond Dissociation Energy and Activation Energy

Bond energy is the energy required to break a bond homolytically. These values are usually expressed in units of kcal/mol or kJ/mol and are referred to as ...

Energy Basics

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 ...

Endergonic and Exergonic Reactions in the Cell

If energy releases during a chemical reaction, then the resulting value&#160;will be a negative number. In other words, reactions that release energy have ...

Activation Energy

Activation energy is the minimum amount of energy necessary for a chemical reaction to move forward. The higher the activation energy, the slower the rate ...

types-of-chemical-reactions-anabolic-and-catabolic

Types of Chemical Reactions: Anabolic and Catabolic

The first law of thermodynamics holds that energy can neither be created nor destroyed&#8212;it can only change form. An organism&#39;s essential function ...

Matter and Its Interactions: Develop a data simulation, based on observations and experimental data of how the pressure, volume, temperature, and mass of a gas are related to each other, to predict the effect on a system of changing one of those variables.** (P: 5, CC: 2, CI: PS1)

Chemical Bonds


Atoms participate in a chemical bond formation&#160;to acquire a completed valence-shell electron configuration similar to that of the noble gas nearest ...

Nuclear Fission

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

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 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 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 ...

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 ...

Matter and Its Interactions: Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction. (P: 5, CC: 5, CI: PS1)

9C.2.2.1.2

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 ...

Properties of Transition Metals

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3&#8211;12 are ...

Predicting Reaction Outcomes

Kinetics describes the rate and path by which a reaction occurs. In contrast, thermodynamics deals with state functions and describes the properties, ...

Redox Reactions

Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another ...

Matter and Its Interactions: Use the periodic table as a model to predict the relative properties of elements based on the patterns of valence electrons. (P: 2, CC: 1, CI: PS1)

9C.3.1.1.1

3 Developing possible explanations of phenomena or designing solutions to engineering problems
 3.1 Developing and using models 
  3.1.1 Students will be able to develop, revise, and use models to represent the students’ understanding of phenomena or systems as they develop questions, predictions and/or explanations, and communicate ideas to others.

Gibbs Free Energy and Reaction Work

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