Questions tagged [physical-chemistry]

The study of chemical systems using the laws and concepts of physics. This usually requires the techniques of thermodynamics, statistical mechanics and quantum mechanics.

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1answer
18 views

Seeing solubility in various cases

[![enter image description here][1]][1] Question is in the image 'match' each option having multiple answers. I have invested a considerable time over this but couldn't solve it. Anyone explaining how ...
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Chemistry involving lab [closed]

I am having problems finding:: Percent silver in alloy? Mass of copper in copper oxide? Mass of copper in alloy? Percent copper in alloy?
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Interpreting phase diagram of mixture of partially-miscible liquid that boils before complete mixing

Source: Atkins' Physical Chemistry, 8th Edition, P.188 This is an example given by the stated reference book. Interpretations on this phase diagram is given. An extract of the interpretations is ...
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1answer
25 views

Different products using different indicators

A question states that 0.1 M solution of compound$$\ce{Na2CO3.NaHCO3.2H2O}$$ is titrated against 0.05M HCL, and that a different amount of HCL is used according to the indicators(phenolphthalein or ...
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Question on chemical equilibrium [closed]

8 moles of so2 and 4 moles of O2 are mixed in a closed vessel.the reaction proceeds at constant temperature. By the moment when equilibrium sets in,80% of the initial amount of so2 enters into the ...
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1answer
396 views

White hot hydrogen gas, like that during a big bang

Difficult to know for certain which field this is. According to what I can discover about it, the big bang explodes into being as white hot hydrogen gas, millions of degrees hot. I'm okay with that ...
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2answers
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How do you manage to liquefy a gas by applying only pressure? [closed]

How can you liquefy a gas by applying only pressure? To increase the pressure of a gas you need a compressor, and when the compressor does work on the gas , it will increase his pressure but at the ...
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1.00 × 10^18 formula units of LiCl =? [closed]

How many total moles of ions are released when the following sample dissolves completely in water? 1.00 × 10^18 formula units of LiCl = ??
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3answers
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Colligative properties of colloids

The following lines are from my textbook: Colloidal particles being bigger aggregates, the number of particles in a colloidal solution is smaller than a true solution. Hence, the values of ...
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18 views

A question about potential difference across a membrane

Membrane potential of living cells arising from the difference of concentration of ions on both sides of the membrane, but why didn't someone use selective polymers as AEM (Anion Exchange Membrane) ...
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How can we compare two orbitals in terms of energy with different n and l values? Why are there energy differences? [closed]

While reading from my book I read that in the transition metals the d orbital is filled up before the p orbitals and this was due to the d orbital being lower energy. My question is, why is this the ...
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Symmetries and degeneracies of the s,p, and d orbitals

Consider the molecular AB_8 (complex with central atom A and 8 B ligands (coordination number 8), for which I determined the point group D_4d) and determine the symmetries and degeneracies of the s, p,...
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Grouping of symmetry classes in chemistry character tables

In the C3v point group, it lists three sigma Vs together in one column (class), and it doesn't list the cVs separately. Consequently there are three irreducible representations. In the C2v point ...
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5answers
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How can we define a non-spontaneous reaction?

Consider a reaction:$$\ce{$aA + bB$ <=> $cC + dD$}$$ The value of reaction quotient at a certain time $t$, $${Q_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}}$$ where the concentrations $[A], [B], [C]$ and ...
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Why are there only 2 peaks in proton NMR of 2-iodopropane? [closed]

I was reading about proton NMR and was drawing high resolution spectra for some of the molecules. I have currently drawn proton NMR spectra for ethanol and ethyl benzoate and got number of peaks as ...
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2answers
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Concentration of gas above aqueous ammonia

I am a physicist who has run into some chemistry in the lab (and unfortunately, I've completely evaded any formal training in chemistry). I have exposed some samples (I think details of the sample are ...
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0answers
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Calculate the heat of formation [closed]

How to Calculate the heat of formation of formaldehyde (HCHO) at 350 K. The standard generation heat is -119 kJ mol-1. The values of the heat capacity (Cp) for constant pressure: formaldehyde: 19.3 J ...
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Effect of optical isomerism on colour of transition metal complexes

I know that different stereoisomers of a given transition metal complex (cis- and trans- forms) have different colours. But do different optical isomers (non-superimposable mirror images) have ...
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Relation between enthalpy, entropy and Gibbs energy at thermal equilibrium

$${\Delta S_{total} = \Delta S_{sys} + \Delta S_{surr}}$$ ... Equation (i) If system is in thermal equilibrium with the surrounding i.e. ${T_{sys} = T_{surr} = T}$ Increase/ decrease in enthalpy of ...
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0answers
24 views

Rates of heterogeneous surface reactions [closed]

This is a question I've been trying to solve for a while, but I haven't taken chemical kinetics yet and just can't seem to figure it out. I have the following reaction: $$\ce{CO2 + ^{\ast} <=> ...
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8 views

Comparison of acidity of aqueous solutions of Lewis Acids

What can be the order of acidity of aqueous solutions of following Lewis acids: $\ce{FeCl3, AlCl3, BeCl2, NiCl2}$ The simplified reactions are: $\ce{FeCl3}$: $\ce{FeCl3 + 6H2O -> [Fe(H2O)6]^3+(...
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1answer
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How to deal with the unit “Coulomb per equivalent”? [duplicate]

In a question that I came across they defined $1\,\pu{F}$ as 96500 coulomb per equivalent. Now as far as my knowledge is concerned $1\,\pu{F} = 96500\,\pu{C/mol}$. The question involved asks to ...
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23 views

State of matter, varying pressure and volume we see a drastic change in solids, as we see in gases and liquids? [closed]

Imagine a solid of a single dimension, to obtain its heat capacity at constant volume $C_p=\frac{\partial U}{\partial T}$ and the constant pressure $C_v=\frac{\partial H}{\partial T}$. It is known ...
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23 views

Combining enthalpies of formation and combustion in the context of Hess's law

I know that you can use enthalpy of combustion to work out formation, and Formation to work out enthalpy change. But can you use enthalpy of formation and combustion data is the same Hess's cycle to ...
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2answers
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Why is the ionic product of water $K_w$ the same in acid, water, and alkali?

Seen on the web: The concentration of [H+] and [OH−] both vary based on the the composition (acid/alkaline) of the solution, but the remarkable thing is that their product does not. When [H+] goes ...
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1answer
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Why is the carbon monoxide triple bond stronger than the nitrogen-nitrogen triple bond?

The $CO$ triple bond has a bond enthalpy of 1072 kJ/mol while the $N_2$ triple bond has a bond enthalpy of 945 kJ/mol, at least according to my source. The molecules are isoelectronic, so I couldn't ...
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5answers
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What exactly is temperature?

I've read at many places that temperature is the average kinetic energy of particles present in an object. I just don't intuitively get how kinetic energy is connected with temperature. And how is ...
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1answer
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How can I calculate Kp given Gibb's free energy? [closed]

I need to solve a problem but I can't seem to figure out how to move from the given values to Kp. Here's the question: 2SO2(g) + O2(g) ⇌ 2SO3(g) ΔrH° = −200 kJ.mol-1 and ΔrS° = −187 J.mol-1.K-1 at ...
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What is the lattice enthalpy of zinc chloride?

I am trying to find a literature value for the enthalpy of solution of zinc chloride to compare with my experimental value but I can't seem to find it. So I'm trying to use the formula: enthalpy of ...
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0answers
25 views

Network covalent bonds during melting

What happens to the intramolecular bonds when a network covalent substance is melted? I understand that in covalent molecular substances, the intermolecular bonds weaken between the molecules once ...
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1answer
77 views

Limiting molar conductivity of multiple solutes

Suppose there is a water solution at $\pu{25 °C}$ with $\ce{Na+},$ $\ce{Mg^2+}$ cations and $\ce{Cl-},$ $\ce{HCO3-}$ anions. Concentrations $[\ce{Na+}],$ $[\ce{Mg^2+}],$ $[\ce{Cl^-}]$ and $[\ce{HCO3-}]...
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1answer
28 views

Electron transfer rates in Marcus Theory [closed]

Electron transfer rates (k) as derived from Marcus theory assumes i) thermal equilibrium and ii) neglects quantum nature of low-frequency phonon modes. Can anyone explain what is at the heart of these ...
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2answers
54 views

What happens if the filter paper in vacuum filtration is BIGGER than the buchner funnel diameter? [closed]

I’m wondering what would happen if the filter paper in a vacuum filtration process is bigger than the buchner funnel diameter? I mean would some differences occurs? Or would the whole experiment ...
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1answer
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Hyperconjugation, stability of molecules, and heat of formation

I recently asked a question about why the heat of formation of organic radicals and positive ions decreases with their size and degree of branching at the radical or ionic site. The user "Buttonwood" ...
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1answer
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Why does the heat of formation of organic radicals and positive ions decrease with their size and degree of branching at the radical or ionic site?

I am currently studying the textbook Mass Spectrometry, third edition, by Jürgen H. Gross. Chapter 2.4.3 Bond Dissociation Energies and Heats of Formation says the following: The heat of formation ...
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What exactly are the graphs of orbitals?

In my QM class we are finding the wave functions of the hydrogen atom. In spherical coordinates, these wave functions are functions of 3 variables: $r,$ $\theta,$ and $\phi.$ My professor stated that "...
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2answers
57 views

Best bags to contain chemical odours?

I have noticed that if you put household or other chemicals in bin liners or freezer bags the plastic doesn't keep the chemicals in. Rather they travel through the bag material and out into the air. ...
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Effect of ionization on dipole moment

Suppose we have a non-dipolar molecule such as carbon dioxide. If carbon dioxide is ionized by some means in the gas-phase, will it develop a dipole moment? I am asking with reference to microwave ...
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1answer
53 views

Intermolecular Forces of Attraction [closed]

Imagine a bottle 85% filled with water and the rest is just air, and the cap is closed. Here are now my questions. Since the cap is closed completely, the air bubble is formed. Is that air bubble ...
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0answers
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Calculating volume of a vessel using idea gas law [closed]

To an evacuated vessel with movable piston under external pressure of $\pu{1 atm},$ $\ce{0.1 mol}$ of $\ce{He}$ and $\pu{1 mol}$ of unknown compound (vapour pressure $\pu{0.68 atm}$ at $\pu{273 K})$ ...
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4answers
379 views

Software recommendations for overlaying molecular structures [closed]

I am looking for a program to overlay the structure of small molecules as an aid for my students in comparing the results of optimization geometries using different optimization methods. At this ...
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0answers
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What is the Gibbs free energy of Lithium-Graphite and Lithium Cobalt-Oxde

I'm trying to do some hand calculations for Lithium-Ion batteries and I can't seem to find the standard state Gibbs free energy of formation for either Lithium-Graphite or Lithium Cobalt-Oxide. They ...
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1answer
191 views

How to use Google’s Alpha-fold to predict a two-protein complex?

Alpha-fold won the CASP competition last year. It used deep learning to predict the secondary structure of a protein given the primary amino acid sequence. Google has released its code a few weeks ...
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2answers
66 views

Is irreversible work a path function? [closed]

In $P/V$ plots of irreversible processes only initial and final state is defined due to sudden compression or rarefaction then how is work done a path function in irreversible processes. Why won't ...
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1answer
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Problem calculating relative molecular mass [closed]

I am starting be re-learn Chemistry after several years. The Book I am using has a test question to calculate the relative atomic mass of: $ (CH_3CO)_2O $ My take Carbon C, $ A_r = 56 $ Hydrogen ...
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1answer
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Is it necessary that hydrolysis of ester will only take place in excess of water?

I was given a question on chemical kinetics in which the statement was given- "The Concentration of water in hydrolysis of ester does not change to much extent" I marked the statement to be false ...
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1answer
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What exchange timescales are needed to cause decoupling in NMR?

I'll try to explain the source of my confusion as clear as possible: (*) The methyl protons in toluene are decoupled because the C-C bond between the methyl group and benzene allows very fast ...
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CO2 dynamics-vector correlations [closed]

I would like to ask if anyone has any information (schematic diagram)of vector correlations for CO2 molecule. (Is it bending in the excited state with μ in plane? How CO fragment can be ejected after ...
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0answers
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Are experimentally determined Hansen solubility parameters available for polypropylene glycols?

Are experimentally determined Hansen solubility parameters available for polypropylene glycols? I already know, approximate values can be calculated by group-contribution methods. But these are only ...
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1answer
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Water-Soluble Photoinitiators for Free-Radical Photopolymerizations?

Could anyone recommend me a good proven free-radical photoinitiator available commercially suitable for (meth)acrylate-based UV-light photo-polymerizations ocurring in water phase, preferably with ...

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