1
vote
0answers
11 views

How can I work out the entropy change of benzene when it changes from vapour into liquid?

I'm stuck on a particular problem which I can't work my head around: Information has been given that :The boiling point of benzene at atmospheric pressure is 353 K and the enthalpy of vaporization of ...
2
votes
1answer
18 views

Does the relationship equation between standard cell potential and equilibrium constant violate potential's intensive properties?

The equation: $$E^{。}_{cell}= \frac{RT}{nF}\ln K_{eq}$$ We all know cell potential is intensive, not affected by the amount, Because: $volt=\frac{joule}{coulomb}$. Both joule and coulomb will be ...
0
votes
0answers
11 views

Gas Stoichiometry [on hold]

-If liquid carbon disulfide (CS2) reacts with 450mL of oxygen to produce the gases carbon dioxide and sulfur dioxide what volume of each product is produced? -Assume that 5.60L of hydrogen gas at STP ...
-1
votes
0answers
14 views

Gas Stoichiometry [on hold]

1 Carbon monoxide reacts with oxygen to produce carbon dioxide. If 1.0L of carbon monoxide at STP, how many liters of oxygen are required to react how many liters of carbon dioxide are produced 2 ...
0
votes
0answers
11 views

How many mole of chlorine gas react with 0.100 mol of metal iron?

How many mole of chlorine gas react with 0.100 mol of metal iron? The chemical equation given was $$\ce{Fe +Cl2-> FeCl2}$$ $0.100 \text{Mol Fe} × \frac{\text{1 mole Cl}}{\text{1 mole Fe}}= ...
0
votes
0answers
17 views

Second question about aqueous solution

I ask a question here but no one prove me the result, so I seek some others examples on the net and I found this, I precise I don't understand them too and if someone here can prove it step by step ...
1
vote
2answers
46 views

Equilibrium constants for lewis acids such as Ca2+

I need to calculate the theoretical $\mathrm{pH}$ in a $50~\mathrm{mL}$ water solution where $6.4\times10^{-4}~\mathrm{g}$ of $\ce{Ca^{2+}}$ is present. The reaction I base this on is the following ...
2
votes
0answers
22 views

Does the third law of thermodynamics apply to all compounds and elements?

According to wikipedia, the third law of thermodynamics is "The entropy of a perfect crystal, at absolute zero (zero kelvins), is exactly equal to zero.". Then, theoretically, could all substances, ...
0
votes
0answers
12 views

Boiling point and melting point of dihalobenzene compounds

In Dichlorobenzene what explains the boiling and melting point of the 3 structures that can be formed? According to Google The melting point decreases in the order- Para>Ortho>Meta And Boiling ...
2
votes
1answer
26 views

Ortho para meta stability

When is the para form of a compound more stable than the ortho form? Similarly when is the meta form more stable? I know that for +I effect ortho para are major products and meta for - I effect. ...
2
votes
1answer
25 views

Carbocation Rearrangement Due To Ring Strain And Back Bonding

Today our teacher told us that the following carbocation rearrangement occurs due to back bonding.I could not really follow what he meant.Can someone please explain what is actually happening during ...
1
vote
1answer
17 views

MO for $N_2^{2-}$

Could someone please show me the MO diagram for $N_2^{2-}$? What I did was since N has 5 valence $e^{-}$, then $N_2$ must have 10, and $N_2^{2-}$ must have 12. And N has $s$ and $p$ orbital mixing. So ...
1
vote
0answers
15 views

Conductivity and Molar Conductivity of Equimolar Solutions of LiCl and KCl

If one took equimolar solutions of $\ce{Li}$ and $\ce{K}$, which would have higher conductivity? Is it the same for molar conductivity? Say, $\ce{LiCl}$ and $\ce{KCl}$, of a litre each. Also, as ...
0
votes
0answers
13 views

How to define custom force in quantum chemistry packages?

I dont know if this is really applicable but I want to add a custom force ( say F(x,y,z) ) to some atoms in my geometry optimization. Is there any way to add such forces to the DFT calculation? ( ...
-1
votes
0answers
13 views

Gold is arranged in a ccp lattice. How many voids are present in Gold if its atomic weight is 197 [on hold]

I need the answer to the above question, please let me know stepwise how to find the answer.
1
vote
0answers
18 views

Which polymers are better for contact lenses? Ionic or non ionic?

As a contact lenses user, I was looking for information about which polymer is better for contact lenses. Ionic or non-ionic? It's very hard to find credible and non-biased info about contact lenses ...
0
votes
2answers
45 views

Titration of C₄H₆O₂

$\ce{C4H6O2}$ (10.75 g) was dissolved in water (250 cm3) and then a 20 cm3 sample was titrated against an alkali metal hydroxide solution. This required 17.35 cm3 of the alkali. What was the ...
1
vote
1answer
33 views

Atomic number $Z$

If electrons were spin-$\frac {3}{2}$ instead of spin-$\frac {1}{2}$ , what would be the atomic number $Z$ for the first noble gas ?
0
votes
1answer
19 views

Spins spin coupling on proton NMR for an aldehyde?

On a proton NMR, does the hydrogen in the CHO group cause coupling, or get coupled itself? Specifically, I a considering 2-methylpropanal. I cannot decide whether the H in the aldehyde group would be ...
2
votes
0answers
20 views

Why does mercury not form amalgam with iron?

I am learning about solutions and while giving an example of a liquid (solute) and a solid (solvent), my teacher told us that mercury forms an amalgam with all the metals except iron. I want to know ...
1
vote
1answer
19 views

Does intramolecular hydrogen bonding occur in dicarboxylic acids?

Consider ethanedioic acid: Could it form intramolecular hydrogen bonds (between the C=O and HO)?
3
votes
3answers
63 views

When does hydrogen bonding happen?

What kinds of molecules will experience hydrogen bonding (inter and intra)? Why does it occur for some H atoms but not others?
1
vote
0answers
18 views

Is ln(K2/K1) = (∆h°rxn/R)(1/T1 - 1/T2) even when ∆h°rxn varies strongly with temperature?

In all of my physical chemistry books I find the same expression for estimating the equilibrium constant of a reaction at a non-standard temperature. The derivation starts with $R \ln K_\text{eq} = ...
1
vote
1answer
8 views

What is this reference material in spectrophotometry?

First, I should say I never have done any spectroscopies and I am just reading about it. As far as I know, UV-Vis spectrophotometer has 2 beam samples: sample and reference. The sample has very ...
1
vote
0answers
24 views

What type of bonding occurs in isolated silicon?

Would isolated silicon engage in network covalent bonding as quartz does or would it engage in a different kind of bonding? Would germanium display similar qualities? *I am asking what is the bonding ...
0
votes
2answers
30 views

Given a forward reaction with positive enthalpy, is its reverse reaction be endothermic or exothermic?

I'm pretty sure the sign changes. But, I want to be sure if it becomes endothermic or exothermic.
6
votes
1answer
133 views

What is a catemer?

What is a catemer and how does it differ from a dimer? What type of compounds could form catemers and how does their formation influence its crystal structure?
2
votes
0answers
13 views

Inorganic Chemistry: Lattice energy, Madelung constant and Born Exponent

I would like to know if you can find Madelung constants in the data book and how to work out the born exponent for ionic structures such as NaCl, Its something simple but i dont know fully ...
2
votes
1answer
46 views

Problem in reasonning about aqueous solution

I have to build the stability diagram of mercury and I have a problem with this couple: $\ce{Hg^2+}/\ce{Hg2^2+}$ $E^\circ=0.91\ \mathrm{V}$ Exercise says that a the border the concentration is ...
8
votes
3answers
455 views

How can I easily explain to a layperson the difference between types of “contains”

I had a conversation with somebody who had somewhat confused ideas about food. He thought that "all food contains sugar" and when I gave a bottle of oil as the counterexample, he said the glycerol is ...
4
votes
1answer
37 views

Why is glycine hydrochloride more acidic than chloroacetic acid?

I cannot figure out why glycine hydrochloride is more acidic than chloroacetic acid. Could I have figured this out from a pKa table and maybe am just not seeing it? On the table I have in my book ...
2
votes
1answer
32 views

Buffer solution calculation

Preface: Buffer solution (acid-base buffer). I am provided with a weak base, which I will designate B. pKa for B's conjugate acid--which I will designate BH--is 8.1, and its mole weight (sic) is ...
3
votes
1answer
33 views

Factors affecting fluorescence in organic molecules

Rhodamine is a fluorescent dye. What features of the molecule result in it being so highly fluorescent ? I assume the extended conjugated system with a stabilized first excited state is necessary, ...
5
votes
1answer
144 views

Determining Aromaticity?

Could someone help me determining the aromaticity of the compounds? My Attempt: (i) not an aromatic compound since it only has 4 pi electrons that does not satisfy Huckels (4n+2) rule (ii) not ...
2
votes
1answer
14 views

Can we prevent metal corrosion by creating a vacuum around it?

I have a device in a box which has parts of metal. So can I prevent corrosion by creating a vacuum around the metallic object?
-1
votes
0answers
12 views

Which Salts Contain Water Of Crystallisation? [on hold]

Which Salts Contain Water Of Crystallisation? For e.g copper(II)sulphate contains water of crystallisation
2
votes
1answer
44 views

What is the CO2 content in the air in a compartment of air and water, as a function of temperature?

What is the graph of carbon dioxide ($\ce{CO2}$) content in the air in a compartment consisting of 80 percent air and 20 percent ocean sea water as a function of temperature, in the temperature range ...
5
votes
1answer
36 views

Effecting Chemical Change

Apologies in advance as I am not a science person by any definition. By most, I'm probably not a person but we'll let that be. I am studying the notion of "change" in things and focusing on chemical ...
0
votes
0answers
24 views

a chemical model for pde

Consider the initial boundary value problem $$u_t=a(t)u_{xx},\,\,\,0<x<1,\,\,\,t>0$$ $$-ku_x(0,t)=hu(0,t),\,\,\,t>0$$ $$u(1,t)=u_0,\,\,\,t>0$$ $$u(x,0)=f(x),\,\,\,t>0$$ where ...
0
votes
0answers
14 views

Is a Vmax value of 0.79 high or low? [on hold]

Is a Vmax value of 0.79 considered high or low? And what does it say about the enzymes parameters?
1
vote
1answer
20 views

Cohesive Energy Density table request

Quick question: Any one knows a resource for Cohesive Energy Density of some organic materials ? I am not looking for any specific molecule, actually I want to plan my project based on available ...
1
vote
0answers
11 views

What radius best represents reaction distance?

Molecules must be within a certain distance for a reaction to begin as well as satisfying a myriad of other factors. Whilst the exact distance varies from reaction to reaction, is their any ...
3
votes
2answers
36 views

Gaussian Convergence Issue for N2+N PES

I am trying to obtain a potential energy surface (PES) for $\ce{N2 + N}$ combination using scan feature of Gaussian. I have tried different combinations of basis ...
2
votes
2answers
48 views

Stereochemical aspect of heating of cyclohexane-1,2-diol

Does stereochemistry play any role in the heating of Cyclohexane-1,2-diol? If I remember correctly, different products are formed depending on whether the diol is cis or trans. (I think the products ...
2
votes
1answer
43 views

Why does an acid salt possess acidity as well as basicity?

For example, $\ce{BaHPO_{4}}$ has acidity of 2 and basicity 1. Why does this so? Its basicity is 1 because it has 1 replaceable hydrogen ion. But why does this have acidity?
1
vote
0answers
15 views

Why are the axial bonds of PF5 longer than those of the equatorial bonds? (Hybridization)

The axial bonds of $\ce{PF5}$ are longer than those of the equatorial positions. One explanation is that because the axial bonds are experiencing more repulsion than those of the equatorial and ...
2
votes
1answer
18 views

Accelerated Oxidation Of Iron When Coating Breaks

I was presented with the following information: If iron is painted, then oxygen and water are prevented from contacting the metal, and corrosion is avoided. Sometimes the iron is coated with a thin ...
-3
votes
0answers
12 views

Equation for Solubility equilibrium [on hold]

When 1.0M NaCl is added to a saturated solution of AgCl, a white precipitate forms. Write the equation of the equilibrium involved, and use this equation to explain the above observation.
-2
votes
0answers
12 views

How to calculate the solubility product of a saturated solution? [on hold]

I have this question that is from my textbook that is very confusing to me. A $1.00~\mathrm{L}$ solution saturated at $25~^\circ\mathrm{C}$ with Lead(II) iodide contains $0.54~\mathrm{g}$ of ...
-3
votes
0answers
15 views

Solubility Equilibrium [on hold]

A student mixed several solutions of $\ce{Ba(NO3)2}$ and $\ce{NaF}$ until a precipitate begins to form. The following data were recorded: Equilibrium $\ce{[Ba^2+]}$. Equilibrium ...

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