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454 views

Why don't B, C, Si, have ionic forms?

Also, why can some elements such as $\ce{Fe}$ have different ionic forms such as $\ce{Fe^{2+}}$ and $\ce{Fe^{3+}}$? What determines each form?
1
vote
1answer
95 views

Why can some ions have different valence?

Like $\ce{Fe}$, it can be $\ce{Fe^{2+}}$ or $\ce{Fe^{3+}}$, same with $\ce{Ni}$ and $\ce{Co}$, what determines whether the ionic compound will be $\ce{Fe^{2+}}$ or $\ce{Fe^{3+}}$?
1
vote
2answers
598 views

Extraction of starch from soup

I have a solution containing many different organic compounds (originally from leek and potato soup) and I would like to extract the starch from it. However, starch is insoluble in water. How could I ...
3
votes
2answers
6k views

How to calculate ring strain energy

Series A and B below can be viewed in two different ways to annulate an ethano bridge onto four-, five-, and six-membered rings. Using the $\Delta H_f^\circ$ values given (in kcal/mol), how can one ...
4
votes
2answers
8k views

What's the difference between graphite, nanotubes, and fullerenes?

I understand that all of these are made up of carbon atoms but I don't understand what differentiates them. Since they are carbon they all must have covalent bonds, right?
-1
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3answers
15k views

Substance whose solubility increases with decrease in temprature

Is there any chemical substance, whose solubility increases with decrease in temperature ?
3
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3answers
1k views

Are refractive or density based Brix meters better for use with alcoholic drinks?

Assume that somebody wants to measure the sugar content of a liqueur. It seems that there are two types of Brix meters for it, ones which use the solution density and ones which use refraction of ...
0
votes
2answers
1k views

Salinic bridges in voltaic cells

I'm doing a study a study on voltaic cells. I've been working with them for a while and one of the questions that I've had is how does the salt bridge affect the cell. I mean, I know it allows ions to ...
1
vote
2answers
5k views

Predicting bond-strength of metal carbonyls

The metal carbonyls (and similar organometallic compounds) involve a combination of sigma bond, a pi bond and backbonding. The bond strengths under consideration are the metal-carbon bond and the ...
2
votes
2answers
567 views

Why does the position of equilibrium depend only on the relative Gibbs energies of the products and the reactants?

The position of equilibrium, I read, is dependent only on the relative Gibbs energies of the products and the reactants. Why is this so? Surely one must take into account the entropy of mixing of the ...
2
votes
2answers
181 views

cooling/refrigeration essentiality for carbonated softdrinks [closed]

How does cooling/refrigeration help in maintaining the taste and shelf life of food products, especially CSD (Carbonated Soft Drinks)? For example, chilled drinks have a nicer taste than a normal ...
6
votes
2answers
40k views

Are ionic bonds stronger than covalent bonds?

A covalent bond involves overlapping of orbitals while an Ionic bond involves charge separation. Why are bonds formed by the overlapping of orbitals weaker than charge separation; why is an ionic ...
3
votes
2answers
2k views

Why do free electrons exist?

Consider the following question: Why are there free electrons in a metal? The answer suggests that conductors have free electrons because the atoms have a weak attraction on the electrons in the ...
0
votes
2answers
222 views

Are some alkali metals better conductors than others?

I want to know if there is any difference at all between the alkali metals as far as conducting electricity goes.
6
votes
4answers
4k views

My sample of gallium does not melt

I held gallium under a heat lamp. It didn't melt. I didn't even find a thin film of liquid gallium. Can anyone explain why? Does gallium rust?
5
votes
4answers
3k views

Unexpected reaction during acid hydrolysis of cellulose

Recently I tried to hydrolyze some cellulose: I added some acid to it ($\ce{H2SO4}$) then noticed nothing. Even after a few days there was no visible change and after doing some tests for glucose, ...
6
votes
1answer
11k views

Reaction of alkenes with bromine in presence of sodium chloride

Consider the following reaction $$\ce{CH3\bond{-}CH\bond{=}CH2 ->T[$\ce{Br2}$/$\ce{NaCl}$]?}$$ What would be the product(s) for this reaction? I am confused because there are two ...
2
votes
1answer
1k views

Calculating approximate pH of polyprotic acids

When I took up ionic equilibria and titrations after a long break, I found it hard to solve the questions regarding pH calculations of polyprotic acds. Consider these two questions as examples:- ...
1
vote
1answer
12k views

How to determine Delta H from the heat of combustion?

The heat of combustion of 2-propanol at 298.15 K, determined in a bomb calorimeter, is -33.41 kJ/g. For the combustion of one mole of 2-propanol, determine (a) $\Delta U$ and (b) $\Delta H$ So I ...
0
votes
2answers
159 views

Comparision of boiling points

I was comparing boiling points of $\ce{CHCl_3}$ and $\ce{CH_3Cl}$. According to me B.P. of $\ce{CHCl_3}$ should be higher due to it's higher molecular mass than $\ce{CH_3Cl}$, but the answer is ...
3
votes
2answers
264 views

Nearest branch numbering

If the longest carbon chain is symmetric numbering-wise (meaning the numbering schemes are identical both ways) and has all alkyl substituents, should one prioritize the largest alkyl group?
1
vote
2answers
4k views

Would 2 C₂ be 2 moles of diatomic carbon, or 4 moles of carbon?

Would molecules like $\ce{C2, H2}$, etc., be considered 1 mole of diatomic [element] or 2 moles of [element]?
0
votes
1answer
52 views

Z:#Neutrons Ratio

Is there a fixed ratio that can be used to calculate the number of neutrons in the nucleus of the most stable isotope of an element by knowing the atomic number? Side question: if Z is the symbol for ...
2
votes
2answers
11k views

Where does the 9th electron go in a N=O bond?

In the first resonating structure you can see 5 unpaired electrons and 4 shared electrons on nitrogen, then isn't this a extended octet? If it is so, then in which orbital that 9th electron is ...
2
votes
1answer
2k views

Synthetic roadmap from 3-methyl-2-butanol to 2-methyl-2-butanol

This is for a homework assignment, I'm usually very good with reactions and am really disappointed after getting it wrong four times, where did I go wrong?
5
votes
1answer
370 views

How to calculate the frequency of cyclohexane conformational interconversion?

My book mentioned that the energy barrier for cyclohexane to reach the half-chair conformation is $50.6\ \mathrm{kJ\ mol^{-1}}$. It says that from this value, it was calculated that cyclohexane ...
6
votes
3answers
1k views

How to achieve clean dishes and glasses?

I heard that there is a standard about cleaned glass, namely Chemically clean glass supports a uniform film of water, with no hanging droplets visible. I tried to clean my dishes at home using ...
7
votes
3answers
5k views

Reason for vibration of molecules

Why do molecules of a body exhibit vibrational motion? Is it due to interaction between various molecules of the body, or interatomic interactions between atoms in the same molecule? If it is because ...
0
votes
1answer
9k views

What is the mechanism for the oxidation of benzene to maleic anhydride using vanadium pentoxide? [closed]

What is the mechanism for the oxidation of benzene to maleic anhydride using vanadium pentoxide, $\ce{V2O5}$?
1
vote
1answer
233 views

Why is the maximum % for a gold alloy 92%?

The assignment question is asking us to explain why you can't get more than 92% gold in a gold alloy, and I can't seem to find out why it's specifically 92% in either the textbook or online. Any ...
7
votes
3answers
106k views

Are all PP(Polypropylene), i.e. resin code 5 plastics, safe for microwave and steaming?

If a plastic is marked PP as in Polypropylene (i.e. resin code 5), is it automatically safe for steaming and microwaving, such that it wouldn't leach chemicals into the food(besides not melting)?
1
vote
2answers
18k views

Heat Produced when Mg is reacted with HCL

Calculate the heat produced when a strip of $\ce{Mg}$ metal with a mass of $0.0801$ gram is reacted with $50.0$ml of $1.0M$ $\ce{HCl}$ to raise the temperature of water to $7.6^\circ C$ (change in ...
1
vote
0answers
127 views

Any references for adsorption of ions to metal surfaces?

I'm specifically interested in ions that would adsorb to gold surfaces, however I would be incredibly appreciative if someone could direct me to a textbook reference or something more expansive, that ...
2
votes
1answer
130 views

What happens to the hydroxide anion during the electroreduction of water?

The reduction of water at a cathode is represented by the following equation: Cathode (reduction): $\ce{2 H2O_{(l)} + 2e^{−} → H2_{(g)} + 2 OH^{-}_{(aq)}}$ If this is done in a divided cell, what ...
2
votes
2answers
6k views

How does molecular structure affect physical properties?

The question sounds vague and non-specific because my background in chemistry is limited to undergrad college courses. However, I am interested in learning the correlations between the atom-by-atom ...
0
votes
2answers
720 views

What is the implication of not being able to balance the complete combustion reaction equation of methanol?

This question has been intriguing me since 10th or 11th grade. The teacher just told us about it but didn't get into the details of the why. Recently I asked a biochemist but couldn't get an answer. ...
0
votes
1answer
265 views

How does a space group determine crystal structure?

If I have an intermetallic and want to know the specific arrangement of atoms in the lattice, how can I determine that? What I mean is the Cartesian (xyz) position, or the (abc) positions in the ...
2
votes
1answer
5k views

How does iron rust in basic conditions?

I performed an experiment about the corrosion of iron. I used acid and base in the experiment. I understand that the acid speeds up the corrosion of iron. But I don't understand why the base also ...
3
votes
2answers
809 views

Does HCl kill algae?

I live in the tropics, and have a water tank that sits in the sun, forming algae. Every year, I need to scrub the thing out. The plumber I’ve hired for the job wants to flush my water pipes with HCl ...
2
votes
2answers
3k views

Equilibrium rate constants forward and backwards

Correct me If I am wrong, given a reaction at equilibrium, if we say add more concentration of products to the reaction, the rate going backwards would increase to try to get back to equilibrium. I ...
1
vote
1answer
746 views

Unfavorable reactions

How can you make an unfavorable reaction go backwards? From my understanding if we wanted a reaction at equilibrium to go backwards (i.e. form reactants from products), we would add more product into ...
4
votes
1answer
262 views

Can polyatomic ions (CO₃, PO₄, SO₄, NO₃) be considered conjugated systems?

From my perspective these resonance structures allow these specific polyatomic ions to act as donor-acceptor molecules. Many donor-acceptor molecules also tend to be conjugated systems because they ...
11
votes
4answers
641 views

Defining and testing custom made DFT functionals?

What is a good and free software for this endeavor? Any recommended articles on the subject? I want to design dft functionals, trying out different parametrizations and optimizing mixing constants for ...
2
votes
1answer
2k views

Photosynthetic rate calculation

What are the steps in calculating the photosynthetic rate ($\mu\text{mole}\ce{O2}/$ $\text{m}^2 / \text{min}$) for a leaf that has an area of $0.0025 \text{m}^2$ and a $\ce{O2}$ evolution rate of $...
4
votes
3answers
5k views

Does rate of Evaporation change with surface area?

Two vessels of the same volume, in the same location and open to the atmosphere. One is of a small diameter, the other is of a larger diameter. The question is will the vessel with the larger surface ...
2
votes
1answer
120 views

Does isotretinoin affects contraception hormonal pills - Ethinylestradiolum, Drospirenonum

Does isotretinoin affects contraception hormonal pills - Ethinylestradiolum, Drospirenonum? Asking as a pharmacologist not a patient.
5
votes
2answers
3k views

What is the (conceptual) difference between binding energy and adsorption energy?

I know the equations, but I have some difficulty getting the difference between the two concepts of binding energy and adsorption energy.
6
votes
4answers
423 views

How do I create a concentrated solution of singlet oxygen (in the dark)?

Without appealing to reactions that require photons / light, how do chemists achieve a very high concentration of continually produced, though quite short lived, singlet oxygen in aqueous solution (i....
3
votes
2answers
9k views

Can two precipitates form in a precipitation reaction that starts with only two compounds in water? [closed]

Can two precipitates form in a precipitation reaction that starts with only two compounds in water?
-3
votes
1answer
2k views

Which is better leaving group [closed]

How can I compare the leaving group ability of $\ce{Br^+}$ and $\ce{Cl^+}$ ions for the electrophilic substitution reactions for aromatic compounds?

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