Name: oxidation states in redox reactions
Uploaded: 2020-03-26T07:22:24.000Z
Duration: 4 min 56 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry

CHEM.9

CHEM.9.B

Redox Reactions

Redox, abbreviazione di riduzione-ossidazione, è un tipo di reazione chimica classificata dal trasferimento netto di elettroni. In questa reazione, una molecola perde elettroni, chiamata ossidazione, e l'altra molecola guadagna elettroni, chiamata riduzione.
Per aiutarti a distinguere tra i due, ricorda la frase "OIL-RIG", che sta per "l'ossidazione sta perdendo, la riduzione sta guadagnando". La molecola che viene ossidata è chiamata agente riducente perché riduce l'altro reagente. Allo stesso modo, la molecola che si riduce è chiamata agente ossidante perché ossida l'altra molecola.
Ora che abbiamo sistemato la terminologia, diamo un'occhiata a un esempio di reazione redox, la formazione del minerale ossido di magnesio. Durante la reazione, ogni atomo di magnesio perde due elettroni. Pertanto, il magnesio viene ossidato. Ogni atomo di ossigeno guadagna due elettroni; Pertanto, l'ossigeno si riduce.
Tuttavia, non tutte le reazioni sono reazioni ossidoriduzioni. Ad esempio, la reazione dell'ossido di calcio con l'anidride carbonica per formare carbonato di calcio non è una reazione redox. Quindi, come possiamo identificare una reazione redox?
Per fare ciò, tracciamo il numero di ossidazione di ciascun elemento mentre passa dal reagente al prodotto. Il numero di ossidazione è la carica ipotetica che un atomo avrebbe se i suoi legami con i diversi elementi fossero ionici, il che significa che gli elettroni sono assegnati all'atomo più elettronegativo. La somma dei numeri di ossidazione in una molecola è uguale alla sua carica complessiva.
Diamo un'occhiata all'ossido di magnesio. È un composto neutro, quindi la somma dei numeri di ossidazione per magnesio e ossigeno è uguale a zero. Il magnesio può dare due elettroni, quindi il suo numero di ossidazione è più due. L'ossigeno può accettare due elettroni, quindi il suo numero di ossidazione è meno due.
E la reazione? I composti elementari neutri puri hanno un numero di ossidazione pari a zero. Pertanto, sia il magnesio che l'ossigeno iniziano con numeri di ossidazione pari a zero. Sia i numeri di ossidazione del magnesio che quelli dell'ossigeno sono cambiati durante la reazione, quindi questa è una reazione redox.
Ora, diamo un'occhiata alla reazione del carbonato di calcio che abbiamo visto in precedenza. Entrambi i reagenti sono neutri, quindi la somma dei numeri di ossidazione per entrambi i composti è zero. Come abbiamo visto con l'ossido di magnesio, il calcio ha un numero di ossidazione di più due e l'ossigeno meno due. Quindi, il carbonio nella molecola di anidride carbonica ha un numero di ossidazione di più quattro e ogni ossigeno meno due.
Che ne dici del prodotto? Il calcio è più due e il carbonio più quattro, proprio come nei reagenti. Ogni ossigeno è meno due, per un totale di meno sei, con il numero di ossidazione netto zero. Poiché nessuno dei numeri di ossidazione è cambiato, questa non è una reazione redox.
Ora introduciamo i quattro tipi di reazioni redox. La prima è una singola reazione di spostamento, in cui un atomo ne sposta un altro. Lo vedrai in una reazione di termite, in cui un metallo viene ridotto e l'altro metallo viene ossidato.
Il tipo successivo è una reazione di combustione, che si verifica tra un combustibile e un ossidante per formare prodotti ossidati e calore. Lo si vede in laboratorio durante la combustione del metano con l'ossigeno quando si utilizza un bruciatore Bunsen.
La terza è una reazione di sintesi, in cui due reagenti si combinano per formare un unico prodotto, come nella sintesi dell'ammoniaca, dove l'azoto si combina con l'idrogeno per formare ammoniaca.
Infine, il quarto tipo è una reazione di decomposizione, in cui un reagente assorbe abbastanza energia da rompere i suoi legami per formare composti più piccoli. Questo è ciò che accade con i fuochi d'artificio, dove il clorato di potassio si decompone in cloruro di potassio e ossigeno dopo il riscaldamento.
In questo laboratorio, eseguirai e identificherai vari tipi di reazioni redox che trasformano il rame solido in ossido di rame e poi di nuovo in rame solido.

reazioni redox

<h4>Ossidazione e riduzione</h4>
Alcune reazioni chimiche possono essere classificate come reazioni di riduzione-ossidazione o reazioni redox. L'ossidazione è il processo della materia, come un atomo o una molecola ionica, che perde uno o più elettroni, e la riduzione è il processo della materia che guadagna uno o più elettroni.
<h4>Stati di ossidazione</h4>
Ogni atomo in una molecola ha il proprio stato di ossidazione o numero di ossidazione. Lo stato di ossidazione descrive il grado di ossidazione di una molecola rispetto alla sua forma elementare libera. Lo stato di ossidazione è espresso come la carica che un atomo avrebbe se ciascuno dei suoi legami con altri elementi fosse puramente ionico. Ciò significa che gli elettroni nel legame sono assegnati all'atomo più elettronegativo. Lo stato di ossidazione di un atomo nella sua forma elementare libera è definito come 0.
Ci sono alcune regole che vengono seguite per determinare lo stato di ossidazione. Gli elementi del Gruppo I e del Gruppo II hanno tipicamente stati di ossidazione rispettivamente di +1 e +2. L'idrogeno e l'ossigeno hanno tipicamente stati di ossidazione di +1 e -2, rispettivamente, e gli alogeni di solito hanno uno stato di ossidazione di -1. Inoltre, gli stati di ossidazione degli atomi in una molecola si sommano sempre alla carica sulla molecola. Pertanto, lo stato di ossidazione di un atomo non elencato sopra può spesso essere dedotto. Ad esempio, si consideri l'anidride carbonica (CO2), che è una molecola neutra. Se ciascuna delle due molecole di ossigeno contribuisce con -2, lo stato di ossidazione del carbonio deve essere +4 per annullare il -4 dagli ossigeni.
Per un approccio più generale, disegna la struttura di Lewis della molecola, identifica i legami tra i diversi atomi e assegna ogni legame all'atomo più elettronegativo. Quindi, conta il numero di elettroni su ciascun atomo, con ogni legame che contribuisce con due elettroni. Sottrarre il numero di elettroni attualmente presenti sull'atomo dal numero standard di elettroni di valenza per quell'atomo per ottenere il numero di ossidazione.
Consideriamo di nuovo l'anidride carbonica. Ogni ossigeno ha due coppie solitarie di elettroni ed è collegato al carbonio centrale da un doppio legame. L'ossigeno è più elettronegativo del carbonio, quindi ogni legame C=O, che rappresenta quattro elettroni, è assegnato al suo ossigeno. Così, a ogni ossigeno viene assegnato un totale di otto elettroni (quattro dalle coppie solitarie e quattro dal doppio legame) e al carbonio non ne viene assegnato nessuno. Il numero predefinito di elettroni di valenza per l'ossigeno è sei, quindi il numero di ossidazione per ciascun ossigeno è 6 – 8 = -2. Il numero predefinito di elettroni di valenza per il carbonio è quattro, quindi il numero di ossidazione per il carbonio è 4 – 0 = +4.
<h4>Reazioni redox</h4>
Non tutte le reazioni chimiche sono classificate come reazione redox. Una reazione redox è qualsiasi reazione in cui si verifica un cambiamento nello stato di ossidazione di un atomo. Pertanto, per verificare se una reazione è una reazione redox, determinare gli stati di ossidazione di ciascun atomo nei reagenti e nei prodotti e cercare eventuali cambiamenti.
Molte reazioni redox comportano un trasferimento di elettroni direttamente da una molecola o da un atomo all'altro. In queste reazioni, se una molecola, o atomo, guadagna un elettrone, un'altra molecola, o atomo, deve perdere un elettrone. Un modo semplice per ricordare le definizioni di ossidazione e riduzione è attraverso la frase OIL-RIG, che sta per: Oxidation Is Losing – Reduction Is Gaining.
La molecola che guadagna un elettrone viene ridotta, ma è chiamata ossidante o agente ossidante perché ossida l'altra molecola. Allo stesso modo, la molecola che perde un elettrone viene ossidata, ma è chiamata riducente o agente riducente perché riduce l'altra molecola.
Esistono quattro tipi principali di reazione che in genere coinvolgono processi redox.
<ol>
	<li style="font-size:17px">Reazione di spostamento singolo: Un atomo sposta un altro atomo che fa parte di un composto e lo sostituisce.</li>
	<li style="font-size:17px">Reazione di combustione: Un composto viene ridotto da un forte ossidante, tipicamente ossigeno gassoso. Le reazioni di combustione che si verificano tra idrocarburi e composti organici producono tipicamente anidride carbonica e acqua.</li>
	<li style="font-size:17px">Reazione di sintesi: Due reagenti formano un unico prodotto.</li>
	<li style="font-size:17px">Reazione di decomposizione: Un singolo reagente si rompe in due o più prodotti.</li>
</ol>
<h4>Referenze</h4>
1. Harris, DC (2015). Analisi chimica quantitativa. New York, NY: W. H. Freeman e compagnia.

Reazioni redox

Ossidazione e riduzione
Alcune reazioni chimiche possono essere classificate come reazioni di riduzione-ossidazione o reazioni redox. L'ossidazione è il processo di ...

Education

Didattica

JoVE Lab Manual

Chimica

oxidation states in redox reactions

Oxidation states help identify redox reactions. In a redox reaction, oxidation is the loss of one or more electrons, and reduction is the gain of one or more electrons. These reactions are often tracked by changes in oxidation state, also called oxidation number.

Each atom in a molecule has an oxidation state. This number shows how oxidized an atom is compared with its free elemental form. It is written as the charge an atom would have if every bond were purely ionic. In that model, bonding electrons are assigned to the more electronegative atom. An atom in its elemental form has an oxidation state of 0.

Several rules help determine oxidation states. Group I elements usually have +1, and Group II elements usually have +2. Hydrogen is typically +1, oxygen is typically -2, and halogens usually are -1. The oxidation states in a molecule or ion must add up to the total charge, so unknown values can often be found from the rest.

Carbon dioxide is a clear example. CO2 is neutral, so its total oxidation states must add to zero. Each oxygen is usually -2, so carbon must be +4 to balance the two oxygens. Another way to find oxidation numbers is to draw the Lewis structure, assign each bond to the more electronegative atom, and count electrons on each atom.

In CO2, oxygen is more electronegative than carbon, so each C=O bond is assigned to oxygen. Each oxygen gets eight electrons total, including lone pairs and bonding electrons. Oxygen has six valence electrons by default, so its oxidation number is 6 - 8 = -2. Carbon has four valence electrons by default and is assigned none, so its oxidation number is 4 - 0 = +4.

A reaction is a redox reaction when an atom’s oxidation state changes from reactants to products. To check for redox, compare oxidation states on both sides of the reaction. Many redox reactions also involve direct electron transfer between atoms or molecules. If one species gains an electron, another must lose one.

The phrase OIL-RIG helps remember the process: oxidation is losing, and reduction is gaining. The species that gains electrons is reduced, but it is also called the oxidizing agent or oxidant because it oxidizes the other species. The species that loses electrons is oxidized, but it is also called the reducing agent or reductant because it reduces the other species.

Four major reaction types often involve redox processes. In single displacement reactions, one atom replaces another atom in a compound. In combustion reactions, a compound is reduced by a strong oxidant, usually oxygen gas, and hydrocarbons or other organic compounds often produce carbon dioxide and water. In synthesis reactions, two reactants form one product. In decomposition reactions, one reactant breaks into two or more products.

Oxidation States in Redox Reactions

lab techniques

Measuring with Accuracy in the Lab

Measuring with accuracy in the lab starts with careful records, the right tools, and correct reading of data. Scientists use lab notebooks to record how an experiment was done. These notes include the amounts of materials used and each step of the procedure. Without that record, an experiment cannot be repeated in the same way. Balances and glassware are used to measure solids and liquids for experiments. The precision of a measurement depends on the equipment used. Digital balances show the...

scientific measurement and lab skills

Graphs, Curve Fit, and Standard Deviation

Two-dimensional graphs help students compare an independent variable with a dependent variable in science data. In a chemistry example, temperature is the independent variable and volume is the dependent variable. After data are collected, the relationship between the two measurements must be quantified so it can be evaluated and compared with other relationships. A graph can also show when no relationship exists between the two variables. To make a two-dimensional graph, each data point needs...

stoichiometry, product yield, and limiting reactants

stoichiometry-product-yield-and-limiting-reactants

Balancing Equations and Reactant Limits

Chemical equations show how reactants change into products during a reaction. Stoichiometry is the study of the relative amounts of reactants and products. It is based on the Law of Conservation of Mass, which says matter is neither created nor destroyed. Because atoms are only rearranged, the number and identity of atoms must match on both sides of a reaction. That is why a chemical equation must be balanced. A balanced equation has the same number of atoms for each element in the reactants...

redox reactions

Oxidation states help identify redox reactions. In a redox reaction, oxidation is the loss of one or more electrons, and reduction is the gain of one or more electrons. These reactions are often tracked by changes in oxidation state, also called oxidation number. Each atom in a molecule has an oxidation state. This number shows how oxidized an atom is compared with its free elemental form. It is written as the charge an atom would have if every bond were purely ionic. In that model, bonding...

ideal gas law

Gas Laws Behind the Ideal Gas Equation

The ideal gas equation brings together the main gas laws used in chemistry. Gases have molecules that are far apart, so their behavior is described with four measurable variables: pressure, volume, number of moles, and temperature. The ideal gas law links these variables with the gas constant, R, which equals 8.314 J·K−1 mol−1. Boyle’s law describes the link between pressure and volume. When temperature and the number of moles stay constant, pressure and volume change in opposite directions.

acid and base concentrations

Acids, Bases, and pH in Titration

Acids, bases, and pH explain how acidic or basic a solution is. An Arrhenius acid releases hydrogen ions when it dissolves in water, while an Arrhenius base releases hydroxide ions. These reactions also create conjugate partners: an acid forms a conjugate base after losing hydrogen, and a base forms a conjugate acid after losing hydroxyl. Every acid has a conjugate base, and every base has a conjugate acid. pH measures the amount of hydrogen ions in a solution. The pH scale runs from 0 to 14...

buffers

Buffer pH and the Common Ion Effect

Buffer solutions help keep pH steady when acids or bases are added. In water, an Arrhenius acid (HA) dissociates into hydrogen ions, H+, and a conjugate base, A-. More hydrogen ions make a solution more acidic and lower its pH. An Arrhenius base (BOH) dissociates into a conjugate acid, B+, and hydroxide ions, OH-. Strong acids and strong bases usually change pH a lot because they react completely in water and raise the amount of H+ or OH-. Buffers reduce those pH changes. A buffer usually...

enthalpy of reaction

Reaction Heat, Hess’s Law, and Calorimetry

Reaction heat is explained through enthalpy, Hess’s law, and calorimetry. These ideas show how heat moves during chemical reactions and how scientists measure it. Thermodynamics is the study of heat energy and other forms of energy, such as work. Its laws are used across science, from biology to physics. The first law says energy is conserved in an isolated system. Energy can change form, such as thermal energy becoming work, but it cannot be created or destroyed. The second law of...

solubility

Solubility in Water and Other Solvents

Solubility describes how much of a solute can dissolve in a specific solvent. It is usually reported as solute mass per solvent volume or as solute mass per solvent mass. For example, sodium chloride has a solubility of 36 g per 100 mL of water at room temperature. If solubility is given by solvent mass, that mass must be converted to volume for later calculations. Temperature changes solubility. Sodium carbonate dissolves at about 7 g per 100 mL of water at 0 °C, 22 g per 100 mL at room...

metal flame emission

Flame Test Metal Color Clues

Flame testing uses a metal sample and a flame to identify a substance by its color. Each element gives off a characteristic light emission in the flame, so the color can help distinguish one element from another. This same idea appears in fireworks, where different metal components create different colors. The color comes from energy absorbed by the metallic component. When a species absorbs energy, that energy can go into translation, vibration, rotation, or electron excitement. Electron...

balmer series

Hydrogen Emission Lines

Hydrogen emission lines show how electrons move between fixed energy levels in the Bohr model. Niels Bohr proposed this model for the hydrogen atom in 1913. In this model, an electron can only occupy certain orbits, and it cannot exist between them. These energy states are labeled with the quantum number n. The ground state is n = 1. Higher values, such as n = 2, 3, 4, and so on, are excited states. An electron changes state only by absorbing or emitting energy equal to the difference between...

beer's law

Absorbance Spectra and Beer-Lambert Analysis

Absorbance spectra and the Beer-Lambert Law show how light can be used to study molecules in solution. When light hits a substance, it may be absorbed, transmitted, or reflected. A substance often interacts with a range of wavelengths, and each wavelength can affect the molecules or atoms in a different way. When a molecule absorbs light, that energy can be used for translation, vibration, rotation, or electron excitement. Electron excitement is especially important in spectroscopy because it...

concentration dependence

Reaction Order and Rate Constants

Chemical kinetics describes the speed of a chemical reaction. The rate depends on the reaction mechanism, the complexity of the reaction, and the number of reactants involved. Reactant concentration also affects how fast a reaction happens. The rate law is the experimental relationship that connects these factors to reaction rate. In the rate law, each reactant contributes through a reaction order. The general form is r = k[A]^m[B]^n for aA + bB + ... → cC. Here, r is the reaction rate, k is...

temperature dependence

Reaction Rate, Arrhenius, and Catalysts

Chemical kinetics explains how fast a reaction happens and why that speed changes. The reaction rate is the speed of a chemical reaction. It is defined as the change in concentration of a reactant or product over time. Reaction speed depends on several factors, including the concentration of the reactants and the temperature of the reaction. Each reactant affects the rate in a specific way. That relationship is described by the rate law. The rate law is an equation that connects the...

galvanic cells

Battery Power from Redox Reactions

Electrochemistry studies how chemical change and electrical energy are linked. In this branch of chemistry, electrons move from one species to another. That movement can either produce current or be driven by an applied current. The main reaction in electrochemistry is the oxidation-reduction, or redox, reaction. A redox reaction has two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. These changes also shift the oxidation state of each substance. The...

electrolytic cells

Electroplating with Electrolytic Cells

Electrochemistry links electrical energy with chemical change, and electrolytic cells show how electricity can drive a nonspontaneous reaction. In these reactions, electrons move from one species to another. The key chemistry is a redox reaction, or oxidation-reduction reaction, which happens in two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. The substance that loses electrons is the reducing agent, and the substance that gains electrons is the...

proper lab notebook keeping

Recording a Reproducible Lab Experiment

Accurate lab notebook records are essential in science and organic chemistry labs. Without clear notes, descriptions, quantities, and observations, an experiment cannot be repeated or checked. Good record keeping supports reproducibility, which means other people can follow the same work and get similar results. A laboratory notebook is useful in school labs, research settings, and industry. It can also become a legal record when an idea, process, substance, or technique is patented and...

basic organic chemistry techniques

Organic Lab Glassware and Safe Handling

Organic chemistry labs use specific glassware, careful weighing steps, and controlled heating to keep reactions safe and accurate. Beakers and Erlenmeyer flasks are often used for mixing or holding solvents, but they are not meant for measuring volume unless only an approximate amount is needed. Volumetric glassware is used when a precise volume matters. This group includes graduated cylinders, volumetric pipettes, and volumetric flasks. A graduated cylinder is commonly used in the organic lab...

melting points

How Impurities Change Melting Points

Melting point helps identify an organic compound by showing the temperature where a solid turns into a liquid at 1 atmosphere of pressure. It is a physical property, like solubility, density, color, and electronegativity. Because the exact start of melting is hard to measure, the result is reported as a range. The lower end is when the first drops of liquid appear. The upper end is when the last solid has melted. Scientists compare this range with literature values to help identify a compound. <br...

boiling points

Boiling Point and Vapor Pressure

Boiling point and vapor pressure are key physical properties of a liquid. For a pure compound, the boiling point can help identify the substance. In experiments, the boiling point is usually recorded as a range because exact values are hard to measure and may differ by a few degrees from the literature value. Vapor pressure explains why a liquid boils. In a sealed container, some molecules at the liquid surface gain enough energy to escape into the gas phase. At the same time, some gas...

recrystallization

Purifying Crystals by Solubility

Purifying crystals by solubility is a key organic chemistry technique. Recrystallization uses differences in solubility to separate a desired solid product from starting materials, solvent, and impurities. It is one of the three standard purification methods, along with distillation and extraction. Solubility is the maximum amount of a substance that can dissolve in a fixed volume of solvent at a given temperature. Different solutes dissolve in different solvents, and their behavior can vary...

extraction

Separating Mixtures with Solvent Extraction

Solvent extraction is a common way to separate and isolate a target compound in organic chemistry. In this process, a solute moves from one phase to another so it can be separated from unreacted starting materials or impurities. Extraction is also useful when a product is dissolved in a reaction solvent that is hard to remove by evaporation, such as a solvent with a high boiling point. There are three main types of extraction. In solid-liquid extraction, the solute moves from a solid phase...

simple distillation

Separating Liquids by Boiling Point

Separating liquids by boiling point is the goal of distillation. A miscible mixture contains liquids that mix evenly, and it can be heated so that the more volatile liquid evaporates first. Volatility is a liquid’s tendency to vaporize, and boiling begins when bubbles form in the liquid phase. In a closed container, liquid and vapor can reach equilibrium, which means the rate of vaporization equals the rate of condensation. The pressure from the vapor above the liquid is called vapor pressure.

steam distillation

Steam Distillation and Low-Boiling Separation

Steam distillation is a separation method for temperature-sensitive organic compounds. It works best when the organic compound is immiscible in water, meaning the two liquids do not mix. The method helps remove the organic molecule from a non-volatile contaminant without using the higher temperatures needed for many other separations. In steam distillation, the immiscible mixture is heated until both water and the volatile organic compound distill together. The vapor rises to a condenser,...

thin-layer chromatography

TLC Separation by Polarity

Thin-layer chromatography (TLC) separates compounds in a mixture by polarity. It uses the same basic parts as other chromatography methods: a stationary phase, a mobile phase, and the solute. In TLC, the stationary phase is a thin coating on a plate instead of material packed into a column. The stationary phase in most TLC systems is polar silica gel, a form of silicon dioxide. Its surface has OH groups that can form hydrogen bonds. The sample is first spotted on a pencil start line with a...

column chromatography

Separating Mixtures by Polarity

Column chromatography separates compounds in an organic chemistry lab by using differences in physical properties. It is especially useful for microscale separations when less than 10 grams of material is available for analysis. The method can separate a mixture based on solubility, polarity, hydrophobicity, size, and charge. Any chromatography system has three main parts: the stationary phase, the mobile phase, and the sample mixture. In column chromatography, the stationary phase is usually...

hydrolysis of an ester

Soap Formation from Triglycerides

Triglycerides are lipids made of a glycerol backbone linked to three fatty acids. They are common in vegetable oils and animal fats. Plant lipids are the basis of vegetable oils, while animal lipids are used as lard or general sources of fats. A fatty acid has a long carbon chain, usually between 12 and 20 carbons, with a weak organic acid at one end. Some fatty acids contain double bonds. These are unsaturated fats. The double bond usually gives the chain a bent, cis shape. As a result,...

synthesis of luminol

Luminol Chemiluminescence in Forensics

Luminol chemiluminescence shows how a chemical reaction can produce light and help with blood detection. Chemical reactions may be endothermic or exothermic, depending on whether they absorb or release heat as reactants become products. The enthalpy of a reaction is the energy difference between reactants and products, or ΔH. A positive ΔH means the reaction is endothermic. A negative ΔH means it is exothermic. Many reactions do not happen in a single step. They can pass through intermediates...

esterification

Ester Formation and Everyday Fragrances

Esters are organic compounds with a carbonyl group attached to an oxygen that connects to another alkyl or aryl group. Their general formula is RCOOR'. They are often made by reacting a carboxylic acid with an alcohol in an esterification reaction. In this process, the hydroxyl group of the acid is replaced by an alkyl or aryl group. Many simple esters have familiar fruit and flower smells because their structures are small and less complex. Formic acid and methanol can combine to form methyl...

identification of unknown aldehydes and ketones

identification-of-unknown-aldehydes-and-ketones

Carbonyl Tests for Aldehydes and Ketones

Aldehydes and ketones are carbonyl compounds, which means they contain a C=O functional group. A ketone has two alkyl or aryl groups attached to the carbonyl carbon. Acetone is the simplest ketone, with two methyl groups. An aldehyde is similar, but it has at least one hydrogen attached to the carbonyl carbon. Formaldehyde is the simplest aldehyde, and acetaldehyde has one hydrogen and one methyl group. The carbonyl carbon in both aldehydes and ketones is electrophilic because the oxygen atom...

uv-vis spectroscopy of dyes

How Dyes Absorb Visible Light

Dyes absorb visible light because their molecular structure lets them interact with specific wavelengths. When light hits a substance, some light is absorbed and the rest is reflected or transmitted. The color we see depends on the wavelength that is reflected. A blue substance reflects blue light, around 430 to 480 nm, and absorbs the complementary orange region, around 590 to 630 nm. Compounds that do not absorb in the visible range appear colorless to the human eye. Light also has energy and...

identifying alcohols

Alcohol Tests for Primary, Secondary, and Tertiary

Alcohol tests can help sort alcohols by structure and reactivity. Alcohols are organic molecules with a hydroxyl group attached to an alkyl or aryl group, written as ROH. If the carbon with the hydroxyl group has one R group, the alcohol is primary. If it has two R groups, it is secondary. If it has three R groups, it is tertiary. Alcohols can also be aromatic when they contain a benzene ring. Phenol is the simplest aromatic alcohol. To identify an alcohol, chemists can use its chemical...

chemistry

Video completi e incentrati sul curriculum sia per gli istruttori che per gli studenti nei corsi di laboratorio di Chimica introduttiva.

https://cloudfront.jove.com/files/banners/scicat/labbio.jpg

Learn how oxidation states reveal redox reactions, how to assign oxidation numbers, and why oxidation, reduction, and agents matter in chemistry.

Oxidation States in Redox Reactions | JoVE K12

Florida Department of Education

Physical Science

SC.912.P.8

SC.912.P.8.10

Georgia Standards of Excellence

9-12

SC3.

Indicators of Chemical Reactions

Preparati a insegnare Reazioni redox con questa guida per istruttori di 6 minuti. Copre i passaggi chiave di preparazione per il laboratorio Chemistry su JoVE Lab Manual.

Preparazione dell'istruttore per Reazioni redox in Chemistry - Oltre 4.9K visualizzazioni | JoVE Lab Manual

Segui le procedure passo dopo passo di Reazioni redox in questo video di protocollo studente di 15 minuti. Parte della collezione Chemistry su JoVE Lab Manual.

Protocollo studente per Reazioni redox in Chemistry - Oltre 28K visualizzazioni | JoVE Lab Manual

Balancing Redox Equations

Electrochemistry is the science involved in the interconversion of electrical and chemical reactions. Such reactions are called reduction-oxidation, or ...

ionic-compounds-formulas-and-nomenclature

Ionic Compounds: Formulas and Nomenclature

An element composed of atoms that readily lose electrons (a metal) can react with an element composed of atoms that readily gain electrons (a nonmetal) to ...

molecular-compounds-formulas-and-nomenclature

Molecular Compounds: Formulas and Nomenclature

Molecular compounds or covalent compounds result when atoms share electrons to form covalent bonds. Since there is no electron transfer, molecular ...

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

Formula Mass and Mole Concepts of Compounds

Formula Mass of Covalent Compounds

Chemical formulas represent the elemental makeup of substances. For covalent compounds, the formula represents the ...

experimental-determination-of-chemical-formula

Experimental Determination of Chemical Formula

The elemental makeup of a compound defines its chemical identity, and chemical formulas are the most concise way of representing this elemental makeup. ...

Chemical Equations

Chemical equations represent the identities and relative quantities of substances involved in a chemical reaction. The substances undergoing reaction are ...

CHEM.9.A

Chemical Reactions in Aqueous Solutions

Chemical substances interact in many different ways. Certain chemical reactions exhibit common patterns of reactivity. Due to the vast number of chemical ...

Precipitation Reactions

In a precipitation reaction, aqueous solutions of soluble salts react to give an insoluble ionic compound &#x2013; the precipitate. The reaction occurs ...

Oxidation-Reduction Reactions

Oxidation&ndash;Reduction Reactions

Earth&rsquo;s atmosphere contains about 20% molecular oxygen, O2, a chemically reactive gas that plays an essential ...

Oxidation Numbers

In redox reactions, the transfer of electrons occurs between reacting species. Electron transfer is described by a hypothetical number called the ...

Oxidation and Reduction
Some chemical reactions can be classified as reduction-oxidation reactions, or redox reactions. Oxidation is the process of ...

Acids, Bases and Neutralization Reactions

An acid-base reaction is one in which a hydrogen ion, H+, is transferred from one chemical species to another. Such reactions are of central importance to ...

Reaction Stoichiometry

A balanced chemical equation provides a great deal of information in a very succinct format. Chemical formulas provide the identities of the reactants and ...

Limiting Reactant

The relative amounts of reactants and products represented in a balanced chemical equation are often referred to as stoichiometric amounts. However, in ...

Reaction Yield

The theoretical yield of a reaction is the amount of product estimated to form based on the stoichiometry of the balanced chemical equation. The ...

Stoichiometry, Product Yield, and Limiting Reactants

Chemical equations represent how a chemical reaction proceeds from reactants to products through physical or chemical change using chemical formulas.
...

CHEM.9.C

Science concepts. The student understands how matter is accounted for in chemical reactions. The student is expected to:

Oxidation States in Redox Reactions

Description

Transcript

Tags

More videos by Standards