Questions tagged [ions]
For questions about ions - atomic or molecular particles having a net electric charge. Do NOT use this tag just because your question involves ions but is not about the ions themselves (as in electrochemistry, etc.).
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questions with no upvoted or accepted answers
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Conductivity measurements of demineralized water - Unexpected results. Looking for explanation
I'm trying to measure the conductivity change of demineralized water over a few days. But I get results I can't explain.
Setup
This is the circuit and cell I'm using:
Where $R_x$ is the ...
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0
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What is the arrangement of water molecules in a hydration shell around an anion?
I believe I read somewhere that the hydration shell of ions always has hydrogen on the outside, but I can't relocate the exact whereabouts of this. Thus, I decided to ask here, as to what the ...
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Can this happen to superheated water?
Superheated water refers to water that is heating well beyond its usual boiling point under extreme pressure. This cause it to display anomalous property.
I noticed that as temperature increases, so ...
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Why does viscosity decrease when divalent cations are dissolved into aqueous solutions of sodium carboxymethylcellulose?
Sodium Carboxymethylcellulose (CMC/NaCMC/Aqualon) is a common product used in many instances for its unique properties, especially its ability to make solutions viscous. It is well known that the ...
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Brewing tea with deionized water
I am wondering what efect brewing tea (let us assume for the sake of simplicity it is green tea, brewed at about 80 °C) in deionized water might have on the product.
Will the lack of ions in the ...
- 417
4
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301
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Debye-Huckel theory with non-polar solvents
I want to calculate the activity coefficients of mixed solvent salt solutions. I am seeing very strange behavior when I try calculating the activity coefficient of salts in non-polar solvents using ...
- 1,662
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answer
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"Crystal radius" vs "Ionic radius"
What is the difference between crystal radius and ionic radius? For $\ce{NaCl}$ for example the ions combine to a crystal, and I would have guessed they are equal. But I then found an example of data, ...
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How does the surface to volume ratio of ions and their distribution in solution compare to that of suspended nanoparticles in nanofluids?
I am interested in understanding the heat transfer capabilities of fluids.
Nano-fluids are suspensions of nanoparticles (1-100nm sized particles) in a base fluid, often water, oil or glycol. These ...
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3
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498
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Enthalpy change of chromate-dichromate reaction
I am a uni study doing chemistry. I have taken a little bit in highschool before, but not in a while.
In a (nonassessed) practical, we have to predict how heating a chromate/dichromate solution:
$$\...
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Dissociation of H3PO4 and colligative properties
Which of the following solutions that have concentrations of $0.01\ \mathrm{M}$ show the highest elevation in boiling point and why?
A) $\ce{NaCl}$
B) $\ce{CaCl2}$
C) $\ce{H3PO4 }$
D) $\ce{C6H12O6}$ (...
3
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537
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Why don't halogens form cations like H+?
The first ionization energy of hydrogen is $1312\;\mathrm{kJ\cdot mol}^{-1}$, which is larger than that of halogens such as chlorine, bromine, and iodine.
Given that observation, why don't halogens ...
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Possible ionization and fragmentation of chemicals
Is there any generic method where I can know/calculate/generate the possible ionization and fragmentation of a specific chemical, for example, hydrogen chloride and water?
This question is actually ...
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3
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1
answer
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Positive charge on a zwitter ion at pH=7?
I faced this question. But I am having some problems understanding the solution to this:
How can the negative charge on the peptide vanish on $\pu{pH = 7}$? Suppose, we have some $\ce{H+}$ donor on ...
- 2,303
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How do the assumptions of the Nernst equation impact its accuracy?
I was just wondering what impact the assumption that the equilibrium membrane potential for an ion is dependent on just the ion itself (if it is the only thing that is permeable). For instance, if I ...
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How does the membrane potential change so drastically during an action potential?
I understand that the Nernst potentials
$$V = \frac{k_\mathrm{B}T}{e} \ln\left(\frac{c_\mathrm{out}}{c_\mathrm{in}}\right)$$
for all ions inside and outside a cell barely change when an action ...
- 121
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108
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Equilibrium Constants for Diatomic Gases at High Temperatures
I'm new here and I haven't taken chemistry beyond high school, so please forgive the ignorance. I am reading a book about hypersonic aerodynamics, and I am trying to connect some chemistry knowledge ...
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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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Are dopant ions on a crystal lattice free or bonded?
This question seems simple but I don't seem to find many answers right away for this.
When you make a crystal doped with ions (like a luminescent phosphor) and the ions then become a defect in the ...
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0
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Bond dissociation energy of the trihydrogen cation
Recently, in one of the questions in an assignment on the topic of energetics, we were asked to explain why the bond dissociation energy for the trihydrogen cation is much larger than what we would ...
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QM modelling of charge separation reactions
I have a general question regarding the modelling of reactions in which neutral reactants form charged species/ions (in solution). How can one get the energetics approximately right on reactions like ...
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Ions not attached but included in chemical formula for tartrazine
In some diagrams for tartrazine ($\ce{C16H9N4Na3O9S2}$), I see that $\ce{SO3Na}$ is actually represented as $\ce{SO3^-}$ with a floating $\ce{Na^+}$ next to it. How does this work?
EDIT: Wait, are ...
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Ionic radius of Al[3+] compared to K[+], Ca[2+], S[2-], and Cl[-]
I came across this question:
Which of the following is bigger?
$$\ce{K+, Ca^2+, Al^3+, S^2-, Cl-}$$
Now, I know that the radius decreases as the period progresses to the right and increases as we go ...
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2
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0
answers
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How will Back-Bonding affect molecular geometry?
While going through a textbook, I came across the following line:
$\ce{R3C-}$ is pyramidal while $\ce{(CN)3C-}$ is planar due to lack of back bonding from the lone pair of carbon atom into the $\pi^...
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Mechanism Permitting Proton Sponge Effect
The proton sponge effect is utilized as a drug delivery method to release contents packaged in micelles (usually coated in PEG or another protective polymer) into the cytoplasm of a cell after being ...
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Ionic emission spectrum contamination
Imagine that I am trying to identify the presence of ions from among the metals $\ce {Li,Na,K,Ca,Sr, Ba}$ in some solution through their emission spectrum.
By mistake the wire used to introduce ...
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2
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0
answers
494
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Bond Energy of Ions of Molecular Oxygen
Three of the bond energies of $\ce{O2,\ O2^{-},\ O2^{2-},\ O2^+}$ have the values approximately $200, 490$ and $625\ \mathrm{kJ\ mol^{-1}}$. The value for one of the species is uncertain and, ...
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0
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pH, conc vs activity
After studying a somewhat overview of "gamma" activity coefficient (it is not actually in our course but may come in exam as a part of unknown paragraph in ionic equilibrium) I can understand most ...
- 1,165
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Calculating binding energies for excitated levels in potassium?
Suppose a laser is used to excite electronic transitions in potassium from the $3p$ orbitals to ones higher than $4s$. When I attempt to use the Bohr model to calculate binding energies, what I obtain ...
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How to determine relative size of polyatomic ions?
How would you determine the size of a polyatomic ion?
For example when determining which ion is bigger, $\ce{NH2-}$ or $\ce{I-}$, what would you use to determine the size difference?
I know that $\...
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Is Oxide Anion more stable than O^+
O likes to be negative if charged at all. Most metal oxides are of the form $\ce{A^{x+} O^{2-}_{x/2}}$ (where $x$ is the magnitude of the positive charge and $\ce{A}$ is a metal.) Here, despite the $\...
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Why does the passivation layer in DRIE protect just the mask and not the substrate?
Here's a good link as an introduction to DRIE:
BSAC: DRIE Process Development
The $\ce{C4F8}$ (refer Pg. 9 on the link) passivates the entire top layer. But when $\ce{SF6}$ ion bombardment occurs, ...
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A contradiction in the nucleophilic attack of hydride ion based on charge densities
On page 130 of Organic Chemistry by Clayden, it is stated that
Nucleophilic attack by the hydride ion, $\ce{H-}$, is an almost unknown reaction. This species, which is present in the salt sodium ...
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0
answers
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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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Nature of the bonding in hexaaquaaluminium complex
$\ce {[Al(H2O)6]^3+}$ is a well-known complex ion formed by the $\ce {Al^3+}$. I have always had the understanding that only the aqua complexes of transition metal ions, such as $\ce {[Fe(H2O)6]^3+}$, ...
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Kinetic Shift of Simple Cleavage
What is the kinetic shift for the simple cleavage fragmentation if the ion source residence time is 100 microseconds, the time to reach the detector after leaving the ion source is 10 microseconds? (...
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answers
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how can I predict the rate of water ions precipitation on a surface?
Consider a titanium pot that contains 1kg water with the following ions:
$[Ca^{2+}]=22000$ ppm, $[Mg^{2+}]=1500$ ppm,$[Sr^{2+}]=791$ ppm,$[Na^{1+}]=48000$ ppm,$[Cl^{1-}]=120000$ ppm,$[SO_4^{2-}]=...
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answers
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How would you write the empirical formula of an ion?
How would you write the empirical formula of e.g. X2Y42-?
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Different values of concentration of product at equilibrium
$\pu{60g}$ of acetic acid and $\pu{46g}$ of ethyl alcohol are mixed with each other at a constant temperature and allowed to attain equilibrium. At equilibrium $\pu{58.2g}$ of ethylacetate and $\pu{...
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Which is a better measure of polarising power of a cation?
Recently, I have come across literature stating that polarising power of a cation is proportional to the inverse of the surface area $(4\pi r^{2})$ while some associate it with the charge density of ...
- 9,952
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Acid/base separation in nanofiltration
How do semi-permiable membranes handle salts that can separate into an acid and a base based on the "rules" of the membrane?
For example, say I have a nanofiltration membrane that rejects ...
- 1,662
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0
answers
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Bond angles in a oxonium cation
What are the bond angles in protonated alcohol? The bonds in the carbon chain are presumably unaffected by the $\ce{-O^{+}H2}$ group and so in their usual tetrahedral arrangement; what are the angles $...
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Ionizing radiation and oxidation without oxidizing agents
My knowledge on this subject is a bit rusty, so excuse me if I'm asking the wrong question here. I was taking a look at my high school chemistry books from many years ago, and I noticed that reduction ...
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Ar atomic radius Vs. Mg2+, Al3+ and F-
I find it difficult to understand why the Atomic radius of $\ce{Ar}$ is lower than the ionic radius of $\ce{Mg^2+}$ and $\ce{F-}$, and higher than $\ce{Al^3+}$. According to the tables I've seen:
$$\...
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0
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Hydration enthalpy of cations
Can someone provide reliable data on the solvation / hydration enthalpies of $\ce{Ti^{4+}}$ and $\ce{Cr^{3+}}$ ions, or explain which is more stable qualitatively? According to this article1
CFSE in $...
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Distance between ions
I am doing a homework where I am supposed to calculate estimate od distance between two ions in cytoplasm. I have only been given the concentration of an ion. Any help how I should start looking this ...
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Why adding salt to kneading make it wetter?
Last week I tried a new recipe of pizza dough:
65mL of Water;
140g of Wheat Flour (typo 3);
7g of Yeast;
1 big spoon of Olive Oil;
25g of cooked potatoes;
1g of common salt;
I think the recipe uses ...
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What are the factors affecting Boiling Point in Ions?
I understand that for molecular substances, intermolecular forces such as van der Waals forces and hydrogen bonding are the major factors effecting the boiling point.
However, I am not sure about ...
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How do ion–dipole bonds manage to break apart an ionic lattice?
I was reading this answer and its reasoning behind the dissolution of NaCl seems to lie in entropic favorability. However, as it states, many, if not most, dissolution reactions are favored by ...
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Understanding three-dimensional structure of common salt
I started reading through The Feynman Lectures and came across this diagram. What do the numbers next to the nodes in the diagram represent? It's not explained in the text. All that is mentioned is: "...
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Why does sodium chloride not conduct as much as aluminum chloride in water?
I understand how $\ce{NaCl}$ and $\ce{AlCl3}$ dissolves in water but I'm wondering why one is more conductive than the other. Is it their extra ions to conduct the electricity?
I know that in $\ce{...
