Ionic compounds molten

What do all the items in the photographs shown in Figure 5.1 have in common They all involve electricity through a process known as electrolysis. Electrolysis is the breakdown of an ionic compound, molten or in solution, by the passage of electricity through it. The substance which is decomposed is called the electrolyte (Figure 5.2). An electrolyte is a substance that conducts electricity when in the molten state or in solution. 

There are many synonyms used for ionic liquids, which can complicate a literature search. Molten salts is the most common and most broadly applied term for ionic compounds in the liquid state. Unfortunately, the term ionic liquid was also used to mean molten salt long before there was much literature on low-melting salts. It may seem that the difference between ionic liquids and molten salts is just a matter of degree (literally) however the practical differences are sufficient to justify a separately identified niche for the salts that are liquid around room temperature. That is, in practice the ionic liquids may usually be handled like ordinary solvents. There are also some fundamental features of ionic liquids, such as strong... 

Ionic compounds in solution and in molten state are good conductors of electricity. Melts and solutions of covalent substances are nonconducting. Inorganic substances rarely undergo combustion, whereas (organic) covalent compounds do so readily. 

Thinking Critically Explain how ionic compounds, which do not conduct electricity in the solid form, can conduct electricity when they are in the molten state or dissolved in water. 

In ionic solids, electrons are held in place around the ions so they don t conduct electricity. However, in aqueous solution and molten state, they do conduct electricity. Electrical conductance of ionic compounds is not due to movement of electrons but to the movement of ions. 

KC1, NaNOs and LiF are ionic solids. Ionic solids don t conduct electricity in the solid state, however, aqueous solutions and molten forms of ionic compounds contain mobile ions so they can conduct electricity Thus, aqueous KC1 and LiF conduct electricity but solid NaN03 doesn t. 

Ionic Compounds (Ex NaCl, BaCl2, KN03) Electrostatic Positive and negative ions - hard and brittle - high melting point - aqueous solutions and molten states conduct electricity... 

The term ionic liquid (IL) refers to a class of liquids that are composed solely of ions. It is a synonym of molten salt. Although molten salt imphcitly means a high-temperature hquid that is prepared by melting a crystalline salt, IL includes a new class of ionic compounds that are liquids at the ambient temperature [1]. Thus, IL in a narrow sense often stands for room-temperature ionic liquid (RIL). In the present chapter, IL is used in a broader sense and, if necessary, RIL is used to clarify that it is liquid at the ambient temperature. The history of ILs has aheady been reviewed [2]. 

Nonpolar molecular compounds dissolve in nonpolar solvents. Polar molecular compounds and ionic compounds may dissolve in polar solvents. Metals dissolve in other molten metals. These can range from copper, silver, gold, alkali metals dissolving in mercury at room temperature, to chromium, molybdenum, and tungsten dissolving in molten iron. 

I. Ionic compounds tend to have very low electrical conductivities as solids but conduct electricity quite well when molten. This conductivity is attributed to the presence of ions, atoms charged either positively or negatively, which are free to move under the influence of an electric field. In the solid, the ions are... 

Alkali metals are produced commercially by reduction of their chloride salts, although the exact procedure differs for each element. Both lithium metal and sodium metal are produced by electrolysis, a process in which an electric current is passed through the molten salt. The details of the process won t be discussed until Sections 18.11 and 18.12, but the fundamental idea is simply to use electrical energy to break down an ionic compound into its elements. A high reaction temperature is necessary to keep the salt liquid. 

Demonstrate that an ionic compound, potassium iodide or lithium chloride, conducts electricity in the molten state but not as a solid. 

When an ionic compound is heated above its melting point, the molten compound is a good conductor of electricity. 

In a molten ionic compound the positive and negative ions can move around - they can move to the electrodes when a voltage is applied. 

O electrolysis the decomposition (breakdown) of an ionic compound by the passage of an electric cwrent O electrolyte a compound which conducts electricity when molten or in solution in water, and is decomposed in tiie process... 

In molten sodium chloride, the rigid lattice structure is broken. The ions that make up the compound are free to move, and they easily conduct electricity. Similarly, when sodium chloride is dissolved, the sodium and chlorine ions are free to move. The solution is a good conductor of electricity, as shown in Figure 3.14. You will learn more about ionic compounds in solution in Chapter 9. 

Covalent compounds have a wider variety of properties than ionic compounds. Some dissolve in water, and some do not. Some conduct electricity when molten or dissolved in water, and some do not. If you consider only covalent compounds that contain bonds with an electronegativity difference that is less than 0.5, you will notice greater consistency. For example, consider the compounds carbon disulfide, CS2, dichlorine monoxide, C120, and carbon tetrachloride, CC14. What are some of the properties of these compounds They all have low boiling points. None of them conducts electricity in the solid, liquid, or gaseous state. 

Most of the Group IA and IIA metals react with hydrogen to form metal hydrides. For all of the metals in these two groups except Be and Mg, the hydrides are considered to be ionic or salt-like hydrides containing H ions (see Chapter 6). The hydrides of beryllium and magnesium have considerable covalent character. The molten ionic compounds conduct electricity, as do molten mixtures of the hydrides in alkali halides, and during electrolysis of the hydrides, hydrogen is liberated at the anode as a result of the oxidation of H ... 

To get compounds to decompose using electricity, ions must be present, and the sample must be in some liquid form. (Electricity does not pass through solid ionic compounds, even though they are composed of positive and negative ions.) The ions in a liquid are free to move and thus conduct the current. The liquid can be a molten (melted) ionic substance or a solution of an ionic substance in water or another liquid (Figure 8.3). If a solution is used, the compound that is more easily decomposed (the ionic compound or the water, for example) is the one that will react. 

Strong and weak electrolytes conduct electricity only in the liquid state. Strong and weak acids and weak bases conduct in solution only ionic compounds conduct in solution or in the molten state. 

Why do molten ionic compounds generally conduct electric current well, while molten covalent compounds generally do not ... 

Electrolysis of molten NaCI Just as electrolysis can decompose water into its elements, it also can separate molten sodium chloride into sodium metal and chlorine gas. This process, the only practical way to obtain elemental sodium, is carried out in a chamber called a Down s cell, as shown in Figure 21-18. The electrolyte in the cell is the molten sodium chloride itself. Remember that ionic compounds can conduct electricity only when their ions are free to move, such as when they are dissolved in water or are in the molten state. 

Ionic forces are the strongest and act over the longest distances (range). Their magnitude is easily calculated from Coulomb s Law. They are the dominant force in ionic compounds, which most commonly appear as solids but may be gases or molten salts. 

Ionic liquids once referred almost exclusively to molten salts, i.e., salts with melting points well above room temperature, although eutectic mixtures of salts can dramatically reduce melting points. Nowadays, there is a range of ionic compounds that are liquid at room temperature, and often much lower temperatures. Room temperature ionic liquids with properties that are conducive towards synthetic chemistry are described in Section 1.26.3. 

Structural studies in fused salts by means of careful and thorough high-temperature measurements of electrical conductivity, density, viscosity, and laser- Raman spectroscopy have been reviewed. Four problem areas are discussed (1) melting mechanisms of ionic compounds with large polyatomic cations, (2) salts as ultra-concentrated electrolyte solutions, (3) structural aspects and Raman spectroscopy, and (4) electrolysis of molten carbonates. The results in these areas are summarized and significant contributions to new experimental techniques for molten-salt studies are discussed.275 The physical properties and structure of molten salts have also been reviewed in terms of operational (hole, free volume, partly disordered crystal) and a priori (intermolecular potential) models.276 Electrochemistry... 

The ions in an ionic solid can vibrate only about their fixed positions, so ionic solids are poor electrical and thermal conductors. Liquid (molten) ionic compounds are excellent conductors, however, because their ions are freely mobile. 

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