# All Questions

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### How are unstable atoms formed in the first place?

If some atoms are unstable, how were they able form as atoms to begin with?
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### Is distilled/deionizing water corrosive?

I've been reading up on distilled and deionized water and I've come across conflicting information. If compared to regular tap water there are little to no minerals, why are they used to clean ...
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### Is there any way to remember the Organic Functional Groups? [on hold]

In Chemistry, we are coming to a close in the Organic Chemistry unit. We are going to have a test soon, and I still don't understand the Organic functional groups as mentioned on Reference Table R. ...
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### How can i replicate Gecko Feet?

For a 1st year Mech. Eng. physics project, i am trying to make an object that could be used to latch itself to anything.(something that would be helpful to astronauts in outer space). But having ...
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### Hess's Law/Enthalpy of reaction problem

The problem: Chloroform, $\ce{CHCl3}$, is formed from methane and chlorine in the following reaction: $$\ce{CH4(g) + 3Cl2(g) ->3HCl(g) + CHCl3(g)}$$ Calculate $\Delta rH^{\circ}$, ...
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### What does curly brackets {} mean?

I learned that square brackets ex: [H$_2$O] can be used to denote the concentration of water molecules in a fluid. The notation used much in equilibrium problems and such. However, sometimes I have ...
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### Calculate Henry's volatility constant ph effect [on hold]

I have the Henry contant of the ammonia, I have the pH and I have the pk value, how can I calculate the effect of the ph in the Henry constant? I am very lost thanks for the help!!
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### 4 synthesis among which is best [on hold]

We have to synthesise 2 methyl 3 pentanone For that I propose 4 reaction Is I have done it correct If I am correct then Among this which is best.
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### Most effective reaction [on hold]

Why in the following reaction butyl lithium is most effective first reagents . Why we cannot use KOH , sodium ethoxide or sodium acetate.
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### Are these aftershave ingredients harmful for human skin? [on hold]

Ingredients of NIVEA aftershave: Water, Glycerin, Cyclopentasiloxane, Panthenol, Distarch Phosphate, Isopropyl Palmitate, Cyclohexasiloxane, Triceteareth-4 Phosphate, Tocopheryl Acetate (Vitamin E), ...
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### Books for students [duplicate]

Can any one please suggest me books for chemistry . a book for practicing basicbasic problems and advanced problems , it should contain some solved questions. The books should contain all the main ...
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### Composition of dessicant

Most types of dessication packages use silica gel, but are there any that use calcium oxide instead? Here's my reasoning: Calcium oxide absorbs water, forming calcium hydroxide. Adding a (used) ...
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### What is exocyclic compounds? [on hold]

please tell me about the exocyclic compounds and their physical state? I have tried to prepare the,m n but i am not knowing their end point where to stop the reaction so , please help me out.
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### Nitrogen bonding and electron affinity

How does nitrogen bond with itself to form N2 if it has no affinity for electrons? If a nitrogen atom can't pull on the electrons of another nitrogen atom how can N2 have covalent bonds.
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### What is the physics/chemistry behind gold dissolution in water/seawater?

Global ocean contains some amount of dissolved gold (around 0.05-0.005 ppb). Is it ions of gold? Is it just suspended atomic gold (like water vapor in gases - just suspended molecules)? Can pure ...
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### Difference between free energy of formation and free energy of combustion [on hold]

I was wondering what is the main difference among those two values.
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### Understanding Gibbs free energy and enthalpy

Let's say that a reaction releases -50kJ/mol of Gibbs free energy (delta G), and -75kJ/mol of enthalpy (we know that -25kJ/mol went to make sure that the total entropy of universe increased). Now ...
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### Mechanism of polymerization of 4-nitroaniline

Does anyone know the mechanism for/the structure of the product of the explosive polymerization of 4-nitroaniline with concentrated sulfuric acid? My guess is that it is some sort of aromatic ...
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### Why does Manganese have so many stable oxidation states? [on hold]

Manganese ions are stable at various oxidation numbers, going from -3 to +7. Why?
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### Does the reaction between H2SO4 and NH4OH give off heat?

I have a mystery solution lab in chemistry, and I was wondering if the addition of $\ce{H2SO4}$ to $\ce{NH4OH}$ gives off heat? Or is there maybe a precipitate or color change?
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### How are vitamins synthesized? [on hold]

This may be a very easy and generic question, but how are vitamins synthesized (into marketable pills)? For starters, do we stay from plants, animals, rocks? I am particularly interested in the ...
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### How to prepare benzalkonium chloride? [on hold]

Does anyone know of a quasi-efficient synthesis for benzalkonium chloride?
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### Really understanding oncotic pressure and osmosis

I can't wrap my head around the idea of oncotic pressure and osmolarity, logically. I imagine a blood vessel. It is FILLED with proteins...Like a ton of proteins and solutes. So this means, according ...
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### Regioselectivity of pyridine for SnAr

Say there's a pyridine ring with leaving groups on the $\ce{C_2}$ and $\ce{C_4}$ atoms. Why would a nucleophile prefer to attack at the $\ce{C_4}$ position? They form very similar intermediates with ...
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### At temp T K, PCl5 is 50% dissciated at an equilibrium press of 4 atm. At what press it would dissociate to the extent of 80% at the same temp? [on hold]

I have a problem regarding this numerical. I am not able to make out how to proceed.
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### How to determine mobility when two mechanisms exist simultaneously

I'm having some trouble with a homework problem that reads as follows: Two scattering mechanisms exist in a semiconductor. If only the first mechanism is present, the mobility will be 250 cm2 ...
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### hydrogen line spectrum [on hold]

Electron in hydrogen atom is existing in some excited state A. On absorbing some energy(э) it gets further excited state B. on dexcitation from B to ground state the entire sample of such hydrogen ...
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### How much pressure does Gallium exert when it freezes?

Assuming the liquid Gallium is in a sealed container, how much pressure will it exert on its container when it freezes?
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### Supramolecules in Spartan

Maybe someone here is familiar with supramolecules calculations using Spartan? I am new in this area and trying to figure out some things: First - what's the best way to draw them? I tried to draw one ...
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### Why doesn't the bidentate ligand form dative bonding three times?

I was looking at this question where it asked you to work out the final complex formed when an excess of 1,2-diaminoethane is added to and aqueous solution of copper (II) sulphate. So the equation I ...
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### Electrophilic substitution on Cinnamic acid [on hold]

What is the orientation of Cinnamic acid during electrophilic substitution reaction? Ortho/para or mata?
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### How does the relative amount of oxidation of different alcohols affect the amount of energy released?

I am investigating the enthalpy of combustion of different primary alcohols and a website I found briefly mentioned how the relative amount of oxidation of different alcohols affects the amount of ...
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### Is this equation of state original?

I created this equation of state as a personal undergraduate summer project (here is the link) seven years ago: \frac{PV}{n\mathcal RT}-1\propto \left(\frac{n\mathcal ...
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### How does the Rf value change when changing the eluent composition?

A non-polar molecule X is analyzed by TLC chromatography on silica to determine its $R_f$ value. The first eluent was hexane:EtOAc = $9:1$ and the $R_f$ value was $0.5$. In the second run, ...
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### Nitric acid acting as oxidising agent

In the following mechanism, nitric acid acts as an oxidising agent to remove 2 H atoms from the intermediate (in the blue square) My first instinct if given only the reagents would be to protonate ...
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### Intermolecular forces - Covalent bonding

Im confused. How to relate permanent dipole dipole moment, temporary dipole induced dipole and Van der waals forces of attractrion?
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### Find the volume of the solution after reaction [on hold]

What is the total volume solution (in mL) when 1M NaOH is required to be added in 100mL of 1M CH3COOH(Ka =10^-5 ) solution so that its pH becomes 6. I tried solving it by neglecting the basic ...
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### Identifying base in a chemical equation

According to the Bronsted Lowry principle, "base" is a proton acceptor. I've tried to apply this idea to every choice as you can see these red circles in each equation below, but they are all loses ...
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### Typography of Orbitals

For mhchem, I need to decide on a typographical representation of orbitals. Wikipedia tells me, there are atomic orbitals with letters s, p, d, f and g. In a later ...
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### Transition Metals colours and electron absorbtion

I understand that when d-orbitals split some electrons can occupy the higher orbitals by absorbing frequencies of light, but do these electrons then fall back to their original ground states? If so, ...
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### Formation of Bands in Semi-Conductors

At school, we are learning about semi-conductors and their applications in modern electronics. One of the features of semi-conductors is that there is a small energy gap between the valence and ...
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### How should I think about potential energy surfaces for reactions of complex systems?

I've recently started doing some computational chemistry, studying the reaction dynamics of some moderately complex organic and inorganic reactions. I'm doing things like finding maxima, minima, TS's, ...
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My input was ...
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### Explaination for covalent solids being brittle

Brittleness of Ionic solids is caused due to repulsion between similar charges when layers slide.But Covalent Solids do not have such repulsions. Do they ? so why are they described as being ...
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### Net change in moles of gas combustion of octane

I was looking at a website which says that the net change in moles is 9 for this reaction, but I don't understand why. I would have thought the change would have been the difference between 27 and 34. ...
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### Heating of mixture of gases with one gas barely above its boiling point

What happens when mixture of two gases is heated in a closed container? If one gas expands faster than the other and increases pressure of the container enough so that the boiling point of the other ...
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### Hexane and clear, nonpolar liquids [on hold]

first question: Does n-hexane corrupt rubber or plastic? second question: Is there a clear, non-polar, easy to find, cheap and nonhazardous liquid? I would like a list. I want to build a flying ...
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### Does halogenation by PBr3 lead to an inverted product?

$\hspace{4.5cm}$ I think it follows the $\mathrm{S_Ni}$ mechanism and would not lead to Walden inversion, but the answer says otherwise. (the problem didn't indicate the presence of pyridine in the ...