# All Questions

38,056 questions
Filter by
Sorted by
Tagged with
209 views

### Spontaneous inequilibrium in a gas in an isolated system?

Can an isolated system(of several phases) in equilibrium by itself move out of equilibrium? if a system contains for example an inflammable gas dispersed with another combustible gas such that the ...
8k views

### How can antibonding orbitals be more antibonding than bonding orbitals are bonding?

In molecular orbital theory, the fact that a bonding and antibonding molecular orbital pair have different energies is accompanied by the fact that the energy by which the bonding is lowered is less ...
5k views

### Spontaneous explosion of a bottle containing alcohol and milk

A friend of mine gave me a bottle of home-made liquor which is a concoction of pure alcohol and sweetened milk. I accepted his gift happily and then I put the bottle in my cocktail cabinet. After an ...
12k views

### Homemade preservative for natural aloe-vera gel?

I suppose this question can be extrapolated to food in general, but it is the case that I would like to know if there are any methods that would help me to keep the aloe gel fresh, i.e. avoiding it to ...
67k views

### How does the reaction Mg + O₂ → MgO occur? [closed]

$\ce{Mg + O2 → MgO}$ Magnesium, oxygen and magnesium oxide form the above equation. How? What do I need to learn to do this? atomic numbers/ valencies?
436 views

### Is there a specific term for reactions of the form A + B → C + D?

I'm working with an abstract model of chemical reaction networks. In this model, some of the reactions have the form $\ce{A + B <=> C}$ and others have the form $\ce{A + B<=>C + D}$. I'm ...
547 views

### What does under-stoichiometric or stoichiometric mean?

When people talk about oxides like $\ce{SiO2}$ or $\ce{Al2O3}$, they use expressions like stoichiometric or under-stoichiometric. I understand that this refers to the relative composition of materials,...
188 views

### Can high-tin bronze be made sharper than low-tin bronze?

I am not sure how sharpness is measured, but I do know that certain materials can be designated sharper than others, for example obsidian is said to be the sharpest material: The prismatic glass ...
3k views

### Writing the net reaction for reaction of sodium hypochlorite with hydrochloric acid and potassium bromide

I am currently taking a general chemistry course and during a lab they had us do the following procedure: Place $\pu{2 mL}$ of $5\%$ $\ce{NaClO}$ solution in a test tube. Add $10$ drops of ...
2k views

### Alternatives to Congo Red?

I require Congo red indicator for an experiment I wish to perform involving dipping a cellulose sponge into an acid and a base. I first want to dye the cellulose sponge with Congo red, and observe ...
335 views

### How does caesium’s density change with temperature?

According to Wikipedia caesium’s density is $1.90\ \mathrm{g/cm^3}$ at $\Theta =20\ \mathrm{^\circ C}$. How does this change when $T$ changes? E.g. will it expand when melting?
53 views

### Can I deduct heteronuclear van der waals parameters from homonuclear parameters in a forcefield?

I got a forcefield (OPLS-AA in this case) that lists lennard-jones parameters for all homonuclear van der waals interactions. Is there a way to deduct the heteronuclear vdw-interaction parameters from ...
1k views

### Recreational drugs by half life

I am interested in the Biological Half Life of substances. In the previous wikipedia link, I've already found the half lives of common pharmaceutical products. I can't seem to find similar data for ...
1k views

### Explanation of the Selection rule in light of IR spectroscopy

I am in mathematics, but I am writing a paper on molecular vibrations (because you can use representation theory to handle this). I want to prove the selection-rule, but I also have to give a ...
755 views

### Can we process waste just by decomposing it to homogenous mass and extracting the elements from it?

I. e., what if we just burn trash completely or dissolve it in acid, get the resulting paste and extract pure chemical elements out of it by applying some physics and/or chemistry to it until no more ...
237 views

### How would you change the chirality of a compound such that (S,R) becomes (S,S)? [closed]

How would you change the chirality of a compound such that (S,R) becomes (S,S)? That is how would you synthesise a compound from its diastereomer?
2k views

### How, chemically, would you remove protruding phenyl groups?

How, chemically, would you remove protruding phenyl groups? I mean for instance in the molecule phenethylamine there's a phenyl group sticking out (or protruding) how would you go about removing this ...
12k views

### Normal Spinel and Inverse Spinel

According to my notes, octahedral site stabilization energy (OSSE), sterical effects and electronic effects in stability create a confusion in this theory. However, we are able to solve this problem ...
2k views

### Predicting molecular geometry from a formula

Can someone explain the following types of molecules and predict their structure and shape? It will help my understanding if you could provide an example. ...
17k views

### At equilibrium, the mass of reactants and products are equal. Does that mean the reaction stops?

This one is troubling me, and I even got it wrong in my exam: at equilibrium the mass of reactants and products are equal, does that mean the reaction stops? Please explain this one.
13k views

### How do you find the pH of a solution with a known pKa and Molarity?

How do you find the pH of a solution with a known pKa and Molarity?
22k views

### How to determine the order of boiling points and solubilities for (chloro-)alkanes, ethers, aldehydes, and alcohols?

How to determine the order of boiling points and solubilities for (chloro-)alkanes, ethers, aldehydes, and alcohols? What rules can be applied to make these choices? Take for example the following ...
8k views

### Presumptive test for modafinil?

Given a sample that is probably modafinil plus common fillers, but could be fake, what reagent tests would best determine whether it contains modafinil? Assume a known-good sample for comparison. (...
26k views

### How does sodium bicarbonate act as a deodorizing agent?

I was reading this other question on the site: Deodorizing using baking powder instead of baking soda. Apparently, baking soda is used quite often as a cleaning and deodorizing agent. From what I ...
The density of a gas $\ce{X}$ is $10$ times that of hydrogen. In that case, what is the molecular weight of gas $\ce{X}$? Well what I've done up to now is this: The molecular mass of hydrogen is $M(\... 1answer 166 views ### In acidic solution, what does ClO₃⁻ reduce into? In acidic solution, what does$\ce{ClO3-}$reduce into and, most importantly, why? It's $$\ce{6e- +ClO_{3}^- +6H^+ -> Cl^- + 3 H_2O}.$$ Now, with the gift of foresight, why was the equation for ... 1answer 612 views ### Solid hydrophilic transparant materials that don't dissolve in water I am looking for hydrophilic transparant materials which are solid at room temperature and that don't dissolve in water. I need these for an experiment in which I condense droplets on a plate made out ... 5answers 269 views ### Is it possible for an acid and base to react to form an even stronger base or acid? Is there a combination of an acid and a base that when mixed results in a solution that is more basic or more acidic than the initial base or acid, respectively? If so, do such combinations have a ... 2answers 4k views ### What defines the specific enthalpy of atomization? [duplicate] 1 mol of$\ce{F2}$is turned into$\ce{2F}$(atoms). Is this the specific enthalpy of atomization, or two times that? 1answer 47k views ### Deodorizing using baking powder instead of baking soda I am an engineer and I understand the difference between baking power and baking soda as baking powder is baking soda (alkali) with tartaric acid (acidic) and an inert starch (why? Is this a catalyst ... 2answers 659 views ### Measuring Thermodynamic Stability We can predict whether a reaction can occur spontaneously by calculating the change in Gibbs' free energy. I was just wondering whether there is any general measure of the thermodynamic stability of ... 2answers 23k views ### Does SiO₂ have polar covalent bonds or coordinate covalent bonds? First off, I know$\ce{SiO2}$is a network solid. I am looking at its intramolecular forces between the$\ce{Si}$and the$\ce{O}molecule. On the one hand, it seems to me that this should be a polar ... 2answers 2k views ### Hot and cold air interaction in a sealed environment What would happen if air heated to 1200 degree's Fahrenheit in a sealed environment was injected with colder air? No specific pressure defined yet just a general idea of potential interaction between ... 3answers 16k views ### Why is heating increasing the solubility of sodium hydroxide? \begin{align} \ce{NaOH &-> Na+ + OH-} & \Delta H^\circ &= \pu{-44.51 kJ/mol} \end{align} The dissolution of sodium hydroxide in water is an exothermic process, and so, according to Le ... 1answer 44k views ### Molecular orbital theory & predicting the stability of a molecule? A question in my general chemistry textbook gives me a list of formulas for molecules and ions. It then asks me to determine, using molecular orbital theory, whether or not each would exist in a ... 2answers 296 views ### How was the quantum three-body problem solved? What method was used to solve the quantum three-body problem? I heard it was solved and was not sure about the status of the problem. 2answers 38k views ### Strength of intramolecular vs intermolecular hydrogen bonds Why are intramolecular hydrogen bonds weaker than intermolecular hydrogen bonds? 2answers 4k views ### Carbon atoms in triple bonds [closed] I was trying to know what is the probability for the carbon atoms to rotate .I know that in single bond it is 0 % and I think it is 100 % in double bond but how about the triple bond ? 1answer 6k views ### Why is it hard to reduce titanium dioxide? Titanium is expensive, although it is not rare and titanium dioxide is a ubiquitous component, it's part of such mundane articles as toothpaste, paper or plastics. The reason for that is that the ... 1answer 3k views ### How do I calculate the number of moles in the mixture? 5.5 g of a mixture of\ce{FeSO4.7H2O}$and$\ce{Fe2(SO4)3.9H2O}$requires$5.4 \:\mathrm{mL}$of$0.1 \:\mathrm{N}\ce{KMnO4}$solution for complete oxidation. Calculate the number of moles of ... 1answer 52k views ### What is the mechanism for oxidation of ketones by the Popoff's rule? Ketones are relatively much harder to oxidise, but they do undergo oxidation reactions at extreme temperatures. Our teacher also told us about Popoff's rule which states that, on oxidation of ... 1answer 118 views ### Overlapping oxygens in crystal structure — what's going on? This is a screenshot of a portion of a metal organic framework (MOF). These are two oxygens of two NMP solvent molecules. What I am wondering is why they are so close and overlapping like this. I ... 2answers 36k views ### Is astatine a non-metal or a metalloid? Is astatine a non-metal or a metalloid? A metalloid is an element which exhibits some of the properties of a metal as well as those of a non metal. 1answer 197 views ###$K_{eq} $vs$K_c$I was wondering if there was a difference between$K_{eq}$and$K_c$. I think they both refer to the Equilibrium Constant. If I'm wrong, could you please tell me the difference between the two? Thanks!... 2answers 270 views ### Will borosilicate glass absorb 808nm laser light? Will borosilicate glass absorb 808nm laser light? If it instead refracts, then what is the refractive index? Also, will borosilicate reflect lower frequencies of light like those used in non contact ... 1answer 161 views ### Reconciling multiple inorganic properties for the purposes of learning these elements How can I reconcile all of the chemical properties, physical properties and peculiar behaviour of metals in inorganic chemistry for the purposes of studying these systematically? It is very hard to ... 1answer 3k views ### Boiling and Melting point of Lithium (or any other element that does not occure in free state) The melting and boiling point of Lithium as compared to other members of the Alkali group metals is high. But, Lithium does not occur in the free state. So, what does it mean that it has high ... 3answers 776k views ### How do I figure out the hybridization of a particular atom in a molecule? I'm learning how to apply the VSEPR theory to Lewis structures and in my homework, I'm being asked to provide the hybridization of the central atom in each Lewis structure I've drawn. I've drawn out ... 2answers 3k views ### Chemical formula of ethanol and other carbon compounds Should chemical formula of ethanol be written as$\ce{CH3CH2OH}$or$\ce{C2H5OH}$? And whats the logic behind it? I have seen the former being used more often, so why is ethane represented by$\ce{...
I'm doing exercises on hybridisation, and I was given this molecule: I'm wondering about this (electron deficient) oxygen atom. My intuition says it should be ${sp^2}$ like the answer says, but ...