# All Questions

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### What sort of chemical would require a school to be evacuated?

I am doing research for a fictional story. I want to create an accident which would force students to be evacuated from a school. Is there a type of chemical spill that might take place in a chemistry ...
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### Water Alcohol Azeotropes, Winterization and Extractions

everything is legal where I live. I have a water/alcohol azeotrope with rosin dissolved in the solution. It has now been in the freezer for about 24 hours and now the plant waxes and lipids have sank ...
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### Why is the enthalpy of reaction maximum in NaOH + HF as compared to HCl? [closed]

In the following reactions NaOH + HCl => NaCl + H2O (ΔH1) and NaOH + HF => NaF + H2O (ΔH2) Why is ΔH2 > ΔH1? Isn't HCl more acidic and therefore more exothermic? What is this reason for this?
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### Why is it that the enthalpy of hydration equals the difference of solvation enthalpies of anhydrous and hydrous salts

Taking an example from my textbook At finite dilution of CuSO4, heat is liberated $$\ce{CuSO4(s) -> CuSO4 (aq)}.$$ ΔH of solvation = -15.8 kcal (anhydrous CuSO4 solvation reaction) and when it is ...
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### isotopologue distribution, difference among CID (carbon isotopologue distribution) and MID

I am new into LC-MS/MS stable isotope targeted downstream analysis. I've found numerous papers talking about MID (Mass isotopomer distribution) but in some european publications I found CID (carbon ...
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### Why isn't change in Gibbs free energy always zero for isothermal and isobaric chemical reactions?

$G = H - TS$ $=> dG = dU + pdV + Vdp - TdS - SdT$ At constant pressure and temperature (which is the condition for most chemical reactions) we have $dG = pdV - Tds$ Now, $dq = dU + dW$ ( first law ...
292 views

### Where does the energy from combustion come from?

I am aware that combustion reactions are exothermic. The energy stored in the chemical bonds of the products is less than the energy stored in the chemical bonds of the reactants. The difference in ...
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### Entropy change in a vacuum?

What is the total entropy change of an ideal gas undergoing an adiabatic expansion in a vacuum? It is my understanding that since the expansion is adiabatic, there is no change in entropy change ...
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### Reversible and Irreversible processes

In an ideal world, is moving a piston quickly, a reversible process as there is no heat loss due to friction? (as opposed to a quasi static process)
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### What is change in enthalpy in energy profile? [closed]

Consider an energy profile diagram. My doubt is that why does change in potential energy (PE) equal change in enthalpy here? At constant pressure change in enthalpy equals the net heat exchanged ...
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### What is meant by "charge separation" for resonance structures? [duplicate]

I'm confused about the definition of "charge separation" in the context of resonance structures. One of the rules of stability of resonance structure is "the structure with least ...
22 views

### How to make equimolar solution of 72٪ (12)؜ sulfuric acid and 99% Triehylamine (TEA) [closed]

I need to mix TEA and H2SO4 in equimmolar ratio. Acid is 72% pure and TEA is 99% pure.Both in liquid form. What should be the mass of each liquids? Further can I increase the purity of both liquids ...
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### Is this plastic clip made of polypropylene or polyethylene?

I am trying to re-attach an automotive clip (painted plastic with a yellow (epoxy?) hard adhesive backing) which secures a trim piece back onto the vehicle's roof sheet metal (unpainted (primed?) area)...
53 views

### What do we define as "surroundings" in thermodynamics? [duplicate]

I was thinking about the 2nd law of thermodynamics, and how ΔStotal=ΔSsystem+ΔSsurrounding. You could potentially have a reaction with negative ΔStotal occurring- a non-spontaneous reaction. But by ...
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### Why is it difficult to calculate ΔS of the surroundings (said a teacher)?

My chemistry teacher told me that the Gibbs Free Energy (G) function was created because determination of ΔSsurroundings, and thus ΔStotal was difficult, and we needed something better to explain ...
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### Olivetolic acid synthesis

I have both Malonyl - CoA and Hexanoic Acid at my disposal. There is very little information on the SYNTHETIC process of olivetol acid. From my understanding, you must first convert the two CoA's into ...
31 views

### Do we need to consider hydrogen bonding in organic molecules before deprotonation for comparison of acidic strenghts?

Let's suppose in this question hydrogen bonding would be considered in structure 3 ... if yes, then it would be a weak acid because it will not donate H+, but according to the answer given in the book ...
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### Modeling chemical reaction [closed]

Can someone please tell me how do model chemical reactions, by this I mean prepare input of chemicals on LHS and RHS of the equation. I can see how input CO2 can be prepared and for H+, I think for ...
48 views

### Retrosynthesis of {6-[2-(benzylamino)ethyl]-1,4-dihydropyrimidin-4-yl}methanol

I have {6-[2-(benzylamino)ethyl]-1,4-dihydropyrimidin-4-yl}methanol (at the top) and have to make the retrosynthesis steps for my class. I tried different things but I'm not sure about it. In 1 you ...
24 views

### What is the exact definition for isoelectronic species? [closed]

Suppose, I have two ions with the same number of electrons, but their electronic configuration differs slightly from eachother. Then, will they be called isoelectronic?
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### Relationship between the principal axes of inertia of an enantiomeric pair

If an object is chiral, itself and its mirror image are non-superimposable and represent two distinct version of the same object. A hand, for instance, can be either the right hand or the left hand. ...
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### Do ferrofluid nanoparticles come out of solution when exposed to a solenoid DC field current?

As the electrically-charged ionic tails of surfactants used to attach to the magnetic nanoparticles require the particle to be magnetized to stick to them; if a ferrofluid is passed has a solenoid DC ...
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### How to make a Lithium Ion Cell? [closed]

LiNiCoMnO2 This video shows the opening of Lithium Ion battery at https://www.youtube.com/watch?v=-KAHiCb_8-s Question 1: Can LiNiCoMnO2 powder be made from melting Li,Ni,Co,Mn together at high ...
43 views

### Why are anti bonding orbitals distorted towards the less electronegative element?

Bonding molecular orbitals are distorted towards the more electronegative atom and so the atomic orbitals from this atom contribute more to those bonding orbitals. This implies that anti bonding ...
74 views

### Has anyone added dyes to a mixture about to separated by chromatography in order to visualize where the desired product lies?

Usually in preparative chromatography one needs to know when the desired substance to be separated is coming down the pike. Often this required some sophisticated instrumentation. But, it occurred to ...
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### Mass spec mass calculation difference

This is not a homework question, but for research. I am performing mass spec on serum metabolites using Thermo Q Exactive PLUS with a HESI source which was set to a spray voltage of -2.7kV under ...