Name: conductivity in electrolyte solutions
Uploaded: 2020-09-03T13:38:26.000Z
Duration: 2 min 21 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

NC K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.6.1

Electrolyte and Nonelectrolyte Solutions

Water can dissolve many substances because of its chemical composition. Although its overall electrical charge is neutral, a water molecule has a partial negative charge at its oxygen end, and a partial positive charge at each of its hydrogen ends. This makes water a polar solvent. 

When an ionic solute, such as a solid ionic compound, is added to water, the water molecules interact with the ions of the solute. 

If the strong solute&#8211;solvent attractive forces overcome the solute&#8211;solute interactions holding the compound together, the solute ions are pulled apart.

The polar water molecules surround, or &#8216;hydrate&#8217;, the ions as they are separated. The hydrated ions are then dispersed uniformly throughout the solution. 

When an electric potential is applied to an ionic solution, the ions become charge carriers that move towards the oppositely charged electrodes. This creates a current in the solution; in other words, it conducts electricity. 

Substances that produce electrically conductive solutions when dissolved in polar solvents are called electrolytes. Sodium chloride is one such example.

However, when a molecular compound such as sucrose dissolves in water, its molecules remain intact as

electrolyte and nonelectrolyte solutions

Substances that undergo either a physical or a chemical change in solution to yield ions that can conduct electricity are called electrolytes. If a substance yields ions in solution, that is, if the compound undergoes 100% dissociation, then the substance is a strong electrolyte. Complete dissociation is indicated by a single forward arrow. For example, water-soluble ionic compounds like sodium chloride dissociate into sodium cations and chloride anions in aqueous solution.

<img alt="Chemical reaction equation NaCl(s) + H2O(l) &#8594; Na+(aq) + Cl-(aq), dissolution process diagram." src="/files/core/CDNSource/lessons/1022/1022_Equations-01.png" style="height: 40px;" data-altupdatedat="1761830439000" data-alt="Eq1" />

Other examples of strong electrolytes are hydroxides of group 1 and group 2 metals, and strong acids like HCl and HNO3.

If only a tiny fraction of the substance dissociates into ions, that is, if the compound undergoes partial dissociation in solution, it is called a weak electrolyte. Partial dissociation is indicated by a reversible arrow. For example, weak acids like acetic acid partially ionize in water to give acetate ions and hydronium ions.

<img alt="Acetic acid ionization formula, CH&#8323;COOH &#8652; CH&#8323;COO&#8315; + H&#8323;O&#8314;, chemical equilibrium." src="/files/core/CDNSource/lessons/1022/1022_Equations-02.png" style="height: 40px;" data-altupdatedat="1761830439000" data-alt="Eq2" />

Other examples of weak electrolytes are poorly soluble salts like AgCl and PbCl2, and weak bases like ammonia. 

The electrostatic attraction between an ion and a molecule with a dipole &#8211; called the ion-dipole attraction &#8211; plays an important role in the dissolution of ionic compounds in water. When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them.

Solutions of covalent compounds conduct electricity because the solute molecules react chemically with the solvent to produce ions. For example, pure hydrogen chloride is a gas consisting of covalent HCl molecules. This gas contains no ions. However, an aqueous solution of HCl is a very good conductor, indicating that an appreciable concentration of ions exists within the solution.

Because HCl is an acid, its molecules react with water, transferring H+ ions to form hydronium ions (H3O+) and chloride ions (Cl&#8722;):

<img alt="Acid-base reaction equation, H2O + HCl forming H3O+ and Cl-, chemical formula depiction." src="/files/core/CDNSource/lessons/1022/1022_Equations-03.png" style="height: 40px;" data-altupdatedat="1761830439000" data-alt="Eq3" />

This reaction is essentially 100% complete for HCl (a strong electrolyte). Likewise, weak acids and bases that only react partially generate relatively low concentrations of ions when dissolved in water and are classified as weak electrolytes. 

Substances that do not yield ions when dissolved in water are called nonelectrolytes. Such substances dissolve as neutral molecules in solution, each surrounded by water molecules. For example, a molecular compound like sucrose dissolves in water as intact molecules.

<img alt="Glucose dissolution equation, C6H12O6(s) + H2O(l) &#8594; C6H12O6(aq), chemical reaction formula." src="/files/core/CDNSource/lessons/1022/1022_Equations-04.png" style="height: 40px;" data-altupdatedat="1761830439000" data-alt="Eq4" />

In summary, substances may be identified as strong, weak, or nonelectrolytes by measuring the electrical conductance of an aqueous solution containing the substance. To conduct electricity, a substance must contain freely mobile, charged species. Most familiar is the conduction of electricity through metallic wires, in which case the mobile, charged entities are electrons. Solutions may also conduct electricity if they contain dissolved ions, with conductivity increasing as ion concentration increases. Applying a voltage to electrodes immersed in a solution permits assessment of the relative concentration of dissolved ions, either quantitatively, by measuring the electrical current flow, or qualitatively, by observing the brightness of a light bulb included in the circuit. 

This text is adapted from <a href="https://openstax.org/books/chemistry-2e/pages/11-2-electrolytes">Openstax, Chemistry 2e, Section 11.2: Electrolytes.</a>

Substances that undergo either a physical or a chemical change in solution to yield ions that can conduct electricity are called electrolytes. If a ...

Education

JoVE Core

Chemical Quantities and Aqueous Reactions

chemical-quantities-and-aqueous-reactions

KEY TERMS AND CONCEPTS

conductivity in electrolyte solutions

Electrolyte solutions conduct electricity because they contain mobile ions. The amount of current depends on how many ions are present in the aqueous solution. A solution with more dissolved ions conducts better, while a solution with few or no ions conducts poorly.

Strong electrolytes dissociate completely in water. This complete dissociation is shown with a single forward arrow. Water-soluble ionic compounds such as sodium chloride split into sodium cations and chloride anions in solution. Other strong electrolytes include hydroxides of group 1 and group 2 metals and strong acids such as HCl and HNO3.

Weak electrolytes form only a small number of ions in water. Their partial dissociation is shown with a reversible arrow. Weak acids such as acetic acid partially ionize to form acetate ions and hydronium ions. Weak electrolytes also include poorly soluble salts such as AgCl and PbCl2, as well as weak bases like ammonia.

Ionic compounds dissolve in water because water molecules surround the ions and reduce the attraction between them. This ion-dipole attraction is the force between an ion and a molecule with a dipole. As the solid breaks apart, the ions spread evenly through the solution.

Some covalent compounds also conduct electricity after they react with water. Pure hydrogen chloride is a covalent gas and has no ions, but an aqueous HCl solution is a very good conductor. In water, HCl transfers H+ to form hydronium ions and chloride ions, and this reaction is essentially 100% complete for HCl.

Substances that do not produce ions in water are nonelectrolytes. They dissolve as neutral molecules, each surrounded by water molecules. Sucrose is one example. Strong, weak, and nonelectrolytes can be identified by testing electrical conductance with electrodes in the solution. A current can be measured directly, or a light bulb can show the result by its brightness.

Conductivity in Electrolyte Solutions

reaction stoichiometry

Using Balanced Equations to Predict Amounts

Balanced chemical equations show how much of each substance reacts and forms in a chemical change. The formulas identify the reactants and products, which helps classify the reaction. The coefficients show the relative numbers of each substance, which lets chemists measure the relationships between amounts consumed and produced. These quantitative relationships are called stoichiometry. The word comes from the Greek words stoicheion, meaning element, and metron, meaning measure. Stoichiometry...

limiting reactant

Limiting Reactant in Water Formation

Limiting reactants control how much product forms in a chemical reaction. In a balanced equation, the listed amounts of reactants and products are called stoichiometric amounts. In real reactions, the reactants are not always present in those exact proportions. The limiting reactant is the reactant that gets used up first. Once it is gone, the reaction stops making more product. The other reactant is called the excess reactant. Chemists often use extra amounts of one reactant to make sure the...

reaction yield

Calculating Percent Yield in Reactions

Percent yield shows how much product a chemical reaction actually makes compared with how much it should make. The expected amount is called the theoretical yield. It comes from the balanced chemical equation and the stoichiometry, or mole ratios, in that equation. The theoretical yield assumes that the limiting reactant is completely converted into the desired product. The product collected after a reaction is the actual yield. In many cases, the actual yield is lower than the theoretical...

general properties of solutions

Solvents, Solutes, and Solution Types

Solutions are common mixtures found in everyday life. Ocean water, air, and gasoline are all examples of solutions. These mixtures contain two or more types of atoms or molecules in varying amounts. A solution is a homogeneous mixture, which means its composition is uniform throughout. This is different from a heterogeneous mixture, which has a non-uniform composition. In a homogeneous mixture, the components are evenly spread out and thoroughly mixed. Every solution has a solvent and a...

solution concentration and dilution

Molarity and Dilution in Solutions

Molarity and dilution are key ideas for describing solution concentration. Concentration means the relative amount of one component in a solution. In many solutions, one component is present in much larger amount. That component is the solvent, which acts as the medium that holds the other parts dissolved or dispersed. Water is a very common solvent, so aqueous solutions are common on Earth. A solute is the component present at a much lower concentration than the solvent. Chemists often...

Electrolyte solutions conduct electricity because they contain mobile ions. The amount of current depends on how many ions are present in the aqueous solution. A solution with more dissolved ions conducts better, while a solution with few or no ions conducts poorly. Strong electrolytes dissociate completely in water. This complete dissociation is shown with a single forward arrow. Water-soluble ionic compounds such as sodium chloride split into sodium cations and chloride anions in solution.

solubility of ionic compounds

Solubility Rules for Ionic Salts

Solubility rules help predict whether ionic salts will dissolve in water. Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a set temperature and pressure. It is often measured in molarity, or moles per liter (mol/L). A compound is soluble if it dissolves in water. When a soluble salt dissolves, its ions separate and spread evenly through the solution. This physical change is called dissociation. Potassium chloride, KCl, is a simple example. Water...

chemical reactions in aqueous solutions

Aqueous Reactions and Ionic Equations

Aqueous reactions are chemical reactions that take place in water. Water is a good solvent, so it can dissolve many substances. Because of that, many chemical reactions happen in aqueous solution. In high school chemistry, these reactions are often grouped into three common patterns: precipitation, acid-base, and oxidation-reduction. A precipitation reaction happens when ions in two aqueous ionic compounds exchange partners and form an insoluble salt, called a precipitate. In an acid-base...

precipitation reactions

Predicting Precipitation in Aqueous Reactions

Precipitation reactions happen when two aqueous solutions of soluble salts are mixed and an insoluble ionic compound forms. That solid is called a precipitate. The ions in solution exchange partners, so these reactions are also called double displacement, double replacement, exchange, or metathesis reactions. These reactions are useful in chemistry for identifying metal ions in a compound. They also support gravimetric methods, which measure composition by the mass of a substance. Whether a...

oxidation-reduction reactions

Redox Reactions and Oxidation Numbers

Redox reactions are chemical changes in which electrons move between reactants, and oxidation numbers help track that change. The term oxidation once referred only to reactions with molecular oxygen, but it now covers a wider reaction class called oxidation-reduction, or redox, reactions. Some redox reactions form ionic products. A simple example is the reaction between sodium and chlorine that produces sodium chloride. To follow what happens to each reactant, chemists often write...

oxidation numbers

Assigning Oxidation States in Redox Reactions

Oxidation states help track electron transfer in redox reactions. An oxidation number, also called an oxidation state, is a hypothetical number that shows the effective charge of an atom or element. Chemists assign it by using a set of rules. In an ionic compound, oxidation numbers are based on how many electrons move between reacting species. For example, when calcium chloride forms, calcium loses two valence electrons and the two chlorine atoms each gain one electron. In CaCl2, calcium has...

acids, bases and neutralization reactions

How Acids and Bases Form Ions

Acids and bases form ions in water through acid-base reactions. These reactions move a hydrogen ion, H+, from one chemical species to another. They matter in many natural and technological processes, from chemistry inside cells and in lakes and oceans to the large-scale production of fertilizers, pharmaceuticals, and other useful substances. In water, an acid is a substance that produces hydrogen ions. This is the Arrhenius definition of an acid. The H+ ion is also called a proton. In...

synthesis and decomposition reactions

Building and Breaking in Chemical Reactions

Synthesis and decomposition are two redox reactions that show how substances can be built up or broken down. Synthesis means to make something, while decomposition means to break something apart. These reactions also involve chemical changes and energy changes. Synthesis reactions are also called combination reactions. In a synthesis reaction, two or more substances join to form one more complex substance. They are often written as A + B → AB or A + B → C. One example is the formation of...

key terms and concepts

Learn how strong, weak, and nonelectrolytes differ by ion formation, water solubility, and electrical conductivity in aqueous solutions.

Conductivity in Electrolyte Solutions | 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.

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Interactions Of Matter

Stoichiometry

Virginia  Standards of Learning

HIgh School

CH.5

CH.5.c

Texas Essential Knowledge and Skills

High School

CHEM.11

CHEM.11.A

CHEM.11.B

Alabama Course of Study Science

Matter and Its Interactions

9-12.C.1.5

Physical Science

9-12.PS.3.6

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Structure and Properties of Matter

HS-PS1-10.

Georgia Standards of Excellence

SPS2.

Physical Properties

SPS6.

Solutions and Concentration

SC6.

Solvation vs. Dissociation in Dissolving

Scientific Laws and Theories

Scientific Laws

In science, a law is defined as a concise, verbal or mathematical, statement that summarizes a vast number of experimental observations. ...

The Scientific Method

Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To ...

Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

Classifying Matter by Composition

Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories &mdash; pure substances and ...

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Use models to explain how the scientific understanding of atomic structure has evolved.

PS.Chm.1.1

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

Nuclear Fission

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

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Use models to compare nuclear reactions including alpha decay, beta decay and gamma decay; nuclear fusion and nuclear fission.

PS.Chm.1.2

Atomic Orbitals

An atomic orbital represents the three-dimensional regions in an atom where an electron has the highest probability to reside. The radial distribution ...

The Pauli Exclusion Principle

The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that ...

The Energies of Atomic Orbitals

In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are ...

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and ...

electron-configuration-of-multielectron-atoms

Electron Configuration of Multielectron Atoms

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the ...

Use models to explain how electrons are distributed in atoms.

PS.Chm.1.3

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Atomic Mass

Atoms &mdash; and the protons, neutrons, and electrons that compose them &mdash; are extremely small. For example, a carbon atom weighs less than 2 ...

Molar Mass

The identity of a substance is defined not only by the types of atoms or ions it contains but by the quantity of each type of atom or ion. For example, ...

Use the Periodic Table as a model to predict the relative properties of elements based on the pattern of valence electrons in the outermost energy levels of atoms.

PS.Chm.2.1

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

Construct an explanation to infer the atomic size, reactivity, electronegativity, and ionization energy of an element based on its position in the Periodic Table.

PS.Chm.2.2

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

trends-in-lattice-energy-ion-size-and-charge

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

bond-polarity-dipole-moment-and-percent-ionic-character

Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

lewis-structures-of-molecular-compounds-and-polyatomic-ions

Lewis Structures of Molecular Compounds and Polyatomic Ions

To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:


	Determine the ...

Resonance

The Lewis structure of a nitrite anion (NO2&minus;) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...

Formal Charges

In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...

Exceptions to the Octet Rule

Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:


	...

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, ...

Analyze and interpret data to explain the mechanisms and properties of the two main types of intramolecular (ionic and covalent) bonds.

PS.Chm.3.1

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, ...

Construct an explanation to summarize the influences intermolecular forces have on the properties of chemical compounds.

PS.Chm.3.2

Analyze the structure of atoms and isotopes.

Conductivity in Electrolyte Solutions

Description

Transcript

Tags

More videos by Standards