Questions tagged [ionic-compounds]

Compounds in which at least some of bonds have ionic character stronger than covalent or metallic. Many compounds called salts are ionic compounds but not all of them.

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What are the limitations of the Born-Lande' equation?

The Born-Lande' equation is used to theoretically calculate the lattice energy, $\Delta U$, of ionic compounds. It is often cited as such in literature, $$\Delta U = -\frac{k_Az_1z_2Me^2}{4 \pi \...
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Why does beryllium have an exceptionally high hydration energy?

You would expect solubility of Group $2$ fluorides to increase down the group, as lattice energy plummets much more sharply than hydration energy does. For the most part, this is true: $\ce{BaF2}$ is ...
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What would superionic water ice look like?

Phys.org's Giant lasers crystallize water with shockwaves, revealing the atomic structure of superionic ice links to Nature Physics: Experimental evidence for superionic water ice using shock ...
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Gap in ionic radii

The above picture was shown in a presentation by my prof in inorganic chem as we were discussing ionic radii more in depth (all in pm). These are all isoelectronic radii. Notice the sudden leap in ...
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Does the salinity in seawater affect the process of alkaline hydrolysis?

I am an architecture student doing a project on crematorium spaces. I am looking at resomation or alkaline hydrolysis as an alternative method of disposition of a body. From what I gather from ...
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What type of bonding is present in lithium tetrahydridoaluminate?

I can tell that the negative ion has one bond which is a co-ordinate/dative covalent bond. However, overall, would you say that lithium tetrahydridoaluminate (lithium aluminium hydride) is ionic? If ...
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Calculating the ionic strength of a histidine solution

I'm trying to repeat the calculation of the ionic strength of a solution containing histidine as a buffer I recently read in a paper. In their paper, the authors calculate the ionic strength of a 20 ...
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Expression comparing the Solubility of Ionic compounds

In chemical bonding, I am taught an expression that compares the Solvation Energy and the Lattice Energy of an ionic compound which is being dissolved in a polar solvent (could be water, could be ...
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Tin (II) chloride is white while tin(II) iodide is red. Why?

Tin (II) chloride is white while tin(II) iodide is red. Why? The answer given in my book says: Bigger anion has higher polarizability; more polarization greater is the intensity of colour(...
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Chemical bond at Aluminum / Aluminum oxide interface

I am trying to find out what chemical bond holds aluminum oxide to the aluminum on which it forms. The only information I was able to find on the internet was in a Google book which suggested that the ...
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Why are magnesium chloride and calcium chloride more soluble than sodium chloride?

I read that $\ce{MgCl2}$ and $\ce{CaCl2}$ are more soluble than $\ce{NaCl}$ in water. Solubility of $\ce{MgCl2}$ is $\pu{543 g/L}$ and that of $\ce{NaCl}$ is $\pu{360 g/L}$ (both at $20^{\circ} \pu{C}$...
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Why is the Conductivity trend same in fused and in dissolved or aqueous state of ionic compounds?

For an example if we take $\ce{KCl}$ and $\ce{NaCl}$ then I have understood the part where in aqueous state $\ce{Na+}$ becomes bigger than $\ce{K+}$ hence the conductivity reverses but in fused state ...
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What is the structure of sodium chloride in the liquid state?

I understand that sodium chloride when solid, is a lattice, so NaCl there is an empirical formula,(so, expresses that the ratio of Na to Cl is 1-1), and not a molecular formula expressing exact ...
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On the exact definitions of Frenkel and Schottky defects

The wiki page on vacancy defects says; It is also known as a Schottky defect, although in ionic crystals the concepts are not identical. As far as I'm aware, they're the same. Furthermore, the wiki ...
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why does lithium fluoride have a higher lattice energy than lithium iodide?

Based on my knowledge, lattice energy is proportional to the multiplcation of the charge of the ions, divided by the sum of the radius of ions, as follows. Since iodide has a larger radius than ...
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Why isn't the chemistry of a zinc-air battery (meaningfully) hindered by an activation energy barrier?

Virtually every source I've read pertaining to zinc-air batteries explain the chemistry of it either using these formulae or a simplified version of them: $$ \begin{align} &\text{Anode:} &\...
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Can one describe the bonding of Na to F in terms of molecular orbital theory? What about valence bond theory?

I would kindly appreciate an explanation in terms of the two accepted quantum mechanical theories -valence bond & molecular orbitals- for the electronic energy level structure in natrium fluoride $...
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Bond strength of carbon compounds

I read online that C=O is more stronger than C=N and the reason behind this was, 'Since bond between C and O is more polar hence it will have a slightly higher ionic nature than C and N. As we know ...
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A question about nicotinamide adenine dinucleotide

In the structure of NAD+, why does the nitrogen of pyridine bind covalently to the the first carbon of glucose while the anion stabilizing the nicotine amide ion is the phosphate group? In other words,...
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Comparing thermal stabilities of MgCl2 and BaCl2

I read that to compare thermal stabilities of ionic solids: if the solid has a monoatomic anion, we compare thermal stability on the basis of lattice energy which is inversely proportional to size. ...
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How to interpret the shape in this representation of an electride?

This excellent answer describes the appearance of solvated electrons in ammonia as first a blue, and then metallic color. It is produced by dissolving sodium in ammonia at low temperature. According ...
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polar covalent bond

Please take a look at the image of polar covalent bond in the $\ce{H2O}$ molecule below. My question is given in bold type in the following discussion. Here is my flow of thought that confused me so ...
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What is the most stable oxide of Fr?

I read that the heavier alkali metals, like K, Rb, and Cs all prefer to form superoxides. Since Fr is the heaviest alkali metal, I assumed it would follow the same trend as the previous alkali metals, ...
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Which has more ionic character, LiF or K2O?

After drawing the structures of both and considering dipole moment, doesn't it seems that all K2O should have more ionic character than LiF? My textbook says its LiF.
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Using electron affinity to calculate lattice energy

I am trying to calculate the lattice energy of $\ce{CaBr2}$, I am uncertain of how to incorporate the electron affinity value provided for $\ce{Br2}$ into my calculation. Since electron affinity is ...
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Few basic questions about ionic bonding and batteries (lead)

I've got a few very very basic questions about ionic bonds and their role in batteries. My assumptions (correct me if I'm wrong): Ionic bonds occur between a metal and a non-metal (the non-metal ...
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Why does aluminum chloride have a higher lattice energy than aluminum fluoride?

From the table below (source: McMurry's Chemistry [1, p. 212]), it is evident that $\ce{AlCl_3}$ has a higher lattice energy than $\ce{AlF3},$ even though $\ce{F}$ is smaller than $\ce{Cl}$. Why is ...
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Can solutions of polar covalent compounds conduct electricity?

I learned in class that solutions of polar covalent compounds are weakly conductive, while ionic solutions are strongly conductive. But I'm getting different answers online. According to this lecture,...
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Finding the atomic packing factor (APF) of Sodium Chloride and other FCC ionic compounds

For a piece of coursework I am doing, I need to calculate the atomic packing factor of some ionic compounds. I have had no formal teaching in this area, so what I know comes from information I have ...
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Which atom carries charge in polyatomic ions?

I have a basic confusion regarding polyatomic ions: Is it meaningful to say "which atom" in a polyatomic ion is charged? Consider for instance hydroxide OH$^-$: The oxygen has greater ...
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Why does iodine trichloride dimerize?

In which of the dimerization process, the achievement of the octet is not the driving force $\ce{2AlCl3 \to Al2Cl6}$ $\ce{BeCl2 \to BeCl2}$ (solid) $\ce{2ICl3 \to I2Cl6} $ $\ce{2NO2 \to N2O4}$ ...
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What force causes an electron to jump from say Na to Cl?

Every explanation I can find says something like: valence electrons in metals have low ionising energies and non-metals ''want'' to complete their valence shell. But I can't seem to get my head around ...
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How to determine the van't Hoff factor for different salts in water experimentally?

How do I experimentally determine the van't Hoff factor for different salts in water? I'm going to dissolve each of sodium chloride, potassium chloride, and lithium chloride in $\pu{20 mL}$ of water ...
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Measurement of the lattice energy

The lattice energy of a solid ionic compound is the energy released when one mole of the solid compound is formed from its constituent gaseous ions at $\ce {298 K}$ and $\ce {1 bar}$. However, gaseous ...
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Lattice Energy of MX2 type

While finding the solution to the question that which among BaO and BaCl2 has hi that is energy I found that it was BaO whose lattice energy is high and there were explaining it just with charges. So ...
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Ionic liquids and deep eutectic solvent cation vs anion shape

If we consider an ionic liquid of a deep eutectic such as the choline chloride type DESs, why are ionic liquids (and deep eutectics) with not very symmetric cations and very symmetric anions more ...
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To what extent are the radius ratio rules valid for predicting the crystal structure of an ionic compound?

The ionic radii of $\ce{Ba^2+}$ and $\ce{O^2-}$ in barium oxide are $\pu{135pm}$ and $\pu{140pm}$, respectively. The ratio of the radius of $\ce{Ba^2+}$ to $\ce{O^2-}$ is approximately $0.964$. ...
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Where can I find a downloadable database of basic physical and chemical properties?

The web has many online databases of properties of compounds locked behind search interfaces, but I can't find anything you can actually download. I want a corpus of data that might allow me to, say, ...
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Substituting Ulexite

I'm working on ceramic glaze chemistry. One ingredient I don't have, but want to substitute is ulexite: $$\ce{NaCaB5O6(OH)6.5H2O}$$ I have borax, calcium borate, and calcium silicate: $$\ce{NaB4O7 ...
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Ionic compound gases

Does any molecule containing only ionic bonds exist as a gas in room temperature? In the case of carbon dioxide, it is a covalent molecule which is a gas at rtp. Does the same apply for ionic ...
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Type of reaction between metal and salt

What type of reaction is the following? $\ce{ 10Na(l) + 2KNO3 (s) -> K2O(s) + 5Na2O(s) + N2 (g)}$ So far my best guess has been that it's a double replacement reactions with evolution of gas. Is ...
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Does the activity product decrease with increasing ionic strength?

I have a question regarding what happens to the solubility of $\ce{CaSO_4}$ or the rate that $\ce{CaSO_4}$ will dissolve when we add $\ce{NaCl}$ to the solution: $\ce{CaSO_4}$ will dissolve into $\...
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How to clean copper(II) sulfate crystals from sulfuric acid?

I am going to prepare copper(II) sulfate by electrolysis with sulfuric acid for crystal growing. How would I separate the copper(II) sulfate from the sulfuric acid left over from the electrolysis ...
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AlCl3, Al2O3, Al(OH)3. What is more ionic?

I tried with fajans' rules. First I got AlCl3 and Al2O3. There, because O2- has high negative charge I decided that Al2O3 is less ionic. But my teacher told us that we can get the same thing by ...
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Data for Madelung Constants

Where can I find data for the Madelung constants for various ionic compounds? Specifically, I am looking at silicon tetrachloride, yttrium (III) chloride, zirconium (IV) oxynitrate hydrate, niobium (V)...
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Calculating ionic strength at different concentrations

Zn$^{2+}$ reacts with a molecule, B, in a solution at several different concentrations of NaCl. Determine the charge of the biomolecule and k$_0$ (second order) ​​(assume that Zn$^{2+}$ does not ...
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How to choose descriptors for QSAR/QSPR?

I would like to carry out a QSPR study with ionic liquids. After reading the QSAR/QSPR literature, I am a bit confused on how should I choose molecular descriptors. There seem to be a lot of options, ...
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Balancing a chemical reaction with oxidation numbers

We have been teached how to balance chemical reactions with oxidation numbers in school, but somehow I can't understand it. This is the equation to balance $$\ce{Cu(s) + NO3−(aq) + H+(aq) -> Cu^2+(...
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Linearity of membrane resistance and contact resistance overvoltages in proton-exchange-membrane-water-elektrolyzer-cells (PEM-WE)

I am questioning why the cell component's resistance to the electrons (contact resistance) and protons (membrane resistance) flow follow the ohmic law. This assumption is made in recent papers on PEM-...
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Determining ion charge using rate constants and ionic strength

I am given the following data: The rate constant $k$ at $\pu{25 ^\circ C}$ in a reaction of persulfate ions and iodide ions in a water solution is assumed to vary with the total ionic strength of the ...
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