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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Why does the molar conductivity decrease with increasing charge density?

This is a question in a problem sheet I have been set. Is it do do with the following equation: $\Lambda=\Lambda_0-a\sqrt c$? Surely charge density is proportional to concentration so therefore molar ...
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1answer
28 views

Gibbs free energy of a redox reaction

This is the cell reaction for which I am trying to find out the Gibbs free energy $\ce{2Fe^3+ + Fe -> 3Fe^2+}$ I know these standard reduction potentials $E_\mathrm{Fe^{2+}/Fe} = -0.440\ ...
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17 views

Will the Sulfur-Iodine cycle and Haber Method work at lower pressures and temperatures?

I have a yearlong research project next year in my senior year of high school in which we have to make some product or prototype to solve some issue. My interest was in the Liquid Fluoride Thorium ...
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1answer
41 views

Why do dianions (such as malonate) bind cations more strongly than anions?

Why does a dianion (such as malonate) bind cations more strongly than its equivalent anion (acetate)? Is it simply because of the proximal availability of another O- group that can bind to cations? ...
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22 views

What is the molar mass of vitamin d? [on hold]

Chemistry Project Help for my project. Need answers to questions please !
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21 views

How quickly does sulfur hexafluoride mix with the atmosphere?

A common science demonstration is to float a "boat" on sulfur hexafluoride. How long would the sulfur hexafluoride stay in the container (in the experiment linked above) if the container were to be ...
5
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1answer
53 views

When and why do hot material take heat from cold material?

This is what I read on Chemwiki: Rudolf Clausius was a German physicist, and he developed the Clausius statement, which says "Heat generally cannot flow spontaneously from a material at a lower ...
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24 views

The concentration is unity! Why? [duplicate]

I want to know why concentration of solids and liquids are taken unity in expression of equilibrium constant( heterogenous equilibrium). It is usually mentioned that the density of solids and liquids( ...
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1answer
35 views

Interaction between metalic nanoparticles and aggregation

I can't find any publication to deal with aggregation of colloidal metalic nanoparticles. What type of interaction(s) is/are there between aqeous metalic nanoparticles which give(s) rise to ...
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45 views

Abnormal termination of GAMESS in frequencies calculation

I want to optimize geometry and to analyse frequencies for transition metals ($\ce{Cu}$, $\ce{Mn}$, etc.) compounds using GAMESS. I use Avogadro for preparing input files and I have a problem: one of ...
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1answer
34 views

How to calculate valence factor (n-factor) for a element?

Suppose I am given some reaction in which $$\ce{C6H12O6 -> CO2}$$ and I want to calculate n-factor for this reaction to ultimately calculate equivalent weight of carbon for this reaction. Since ...
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2answers
26 views

Can I use my extech pH 60 meter to measure soil pH if so how?

Can I use my extech pH60 meter to measure soil pH if so how? I included a link to the meter. Extech pH 60
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1answer
936 views

Why is NaCl3 possible?

There. And there. Almost a year ago, a group of scientists claimed to have reached compounds of $\ce{Na}$ and $\ce{Cl}$ with weird stochiometries ($\ce{NaCl3, Na3Cl, NaCl7, Na3Cl2}$ and $\ce{Na2Cl}$). ...
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1answer
229 views

What chemicals help define “taste”?

As we all know that there are 5 tastes : sweet, sour, bitter, umami, salty. So what chemicals are there that help form these tastes, in other words how do our tastebuds experience these tastes? ...
5
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1answer
49 views

Difference between radial,planar,angular and spherical nodes

What is the difference between them ? I think radial nodes and spherical nodes mean the same. And angular and planar mean the same . Reference And finally how many spherical nodes are ...
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1answer
23 views

Order of priority in hybridization of d-orbitals

During hybridization of d-orbitals why the $d_{z^2}$ and $d_{x^2-y^2}$ orbitals are used up before the $d_{xy}$, $d_{yz}$ and $d_{zx}$ ?
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1answer
53 views

Why are C6 dispersion forces named C6?

I'm reading about water models and their dispersion coefficients, and going back to S. C. Wang's work according to the citation of an equation (Google books here) As you can see one citation's to a ...
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1answer
41 views

How to find partial pressures from a given equilibrium constant Kp?

I had following question on my quiz and but I answer it wrong because I can't seem to solve it. It is related to finding equilibrium constant. Question: For the following reaction, at ...
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0answers
25 views

What are the charge carriers in a Silicon wafer?

I have been asked, in a physical chemistry problem sheet, what the charge carriers are in a silicon wafer. I can only imagine that it's the Silicon atoms themselves because there is no mention of ...
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1answer
26 views

How can I calculate the boiling temperature of a pure substance as a function of pressure?

I want to make an algorithm that will give me the boiling temperature of a substance as a function of pressure, the critical temperature of a substance, and the critical pressure of a substance. I ...
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0answers
14 views

physical chemistry- About the existence of Azeotropic composition [duplicate]

What's the reason for the existence of azeotropic composition? At that composition why one component alone cann't be vapourised? Is it because of any extra force on them at that composition?
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2answers
26 views

Frequency, the only real characteristics of electromagnetic radiation ??

My book says: frequency is considered as the only REAL characteristics of electromagnetic radiation, because it is unchangeble if the radiation comes up with some other environment, while the ...
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1answer
18 views

Heat Capacity temperature dependence and Gibbs energy

I got this problem in school as a tool to get ready for International Chemistry Olympiad, but I have some problems with this challenge. So, the problem is to calculate as precise as possible the Gibbs ...
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41 views

What is the reason for this azeotrope formation?

What is the reason for this azeotrope formation? I mean why at that composition one component alone cannot go to vapour phase. Is there any extra force holding the two components together at that ...
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1answer
60 views

How to calculate the bond energy of C-Cl?

$$\ce{C(s) + 2 Cl2 (g) -> CCl4 (g)}$$ \begin{align} \Delta{}H^\circ_\mathrm{f} (\ce{C(g)}) &= 121~\mathrm{kJ/mol}\\ \Delta{}H^\circ_\mathrm{f} (\ce{Cl (g)}) &= 716~\mathrm{kJ/mol}\\ ...
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43 views

Finding identities of diatomics from Spectroscopy and Mass Spec Data

Let's say I have a sample of 2 (assumingly different) diatomics A and B. Through Spectroscopy I found the data below: For molecule A: $$B ̃=2.17690\space cm^{−1}$$ $$D ̃=4.79000×10^{-5} cm^{−1}$$ ...
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1answer
45 views

How can you achieve negative pressure?

Pressure is the magnitude (absolute value) of the force over the area, so how can that result in a negative value for pressure as would happen in certain circumstances?
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1answer
16 views

Why does the graph of compressibility factor(z) vs pressure increase after reaching the minimum?

I understand why it decreases for most of the gases but i cannot understand why it increases after reaching a certain minimum.
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1answer
31 views

Partial pressure and chemical equilibirum

Suppose I am given following reaction in vessel $$\ce{NH4HS_(s) <=> NH3(g) + H2S(g)} $$ $P_{\ce{NH3}}=P_{\ce{H2S}}=1\,\mathrm{atm}$ at Equilibrium , If volume is doubled at this instant then ...
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1answer
31 views

Lambert Beer's law deviations

Can somebody explain as concrete as possible, how the change of temperature and the change of ph leads to deviations of this law ?
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1answer
57 views

Is this a possible explanation as to why sigma bonds are stronger than pi bonds?

Sigma bonds form due to the axial overlap of two orbitals whereas pi bonds form due to their lateral overlapping. Since the former is more effective, we can say that sigma is stronger than pi. We mean ...
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1answer
18 views

Spin coat of Graphene oxide on glass slides

I would like to spin coat Graphene oxide on the glass slides and intend to have a thickness of 100nm/0.1micrometre. May I know what is the amount of Graphene oxide to be poured onto the glass slides, ...
2
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2answers
83 views

Can we really beat the speed of light? [closed]

This is a rather physics question but I wanted to get an insight from a chemistry perspective. I heard from some that you can beat the speed or go faster than it but is that really true. Physicists as ...
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1answer
45 views

How to calculate the enthalpy of formation of hydrazine from tabulated values?

I've been given a problem asking: Estimate the standard enthalpy of formation of hydrazine, $\ce{N2H4(g)}$, from the following data. \begin{align} \Delta{}H_\mathrm{B}(\ce{H2}) &= ...
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0answers
28 views

Radial Distribution Function for a Hard Sphere Gas in the Percus-Yevick Approximation - Is There a Quick Way to Evaluate it Numerically?

The question is as in the title. I know that for a one-component hard-sphere gas, there is an analytic solution in the $\vec{k}$-space (PRA, 5, 939). I know that to obtain the correct solution in ...
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0answers
29 views

What does the peak separation of carbon dioxide IR rotational-vibrational spectrum corresponds to and why?

Spectrum of $\ce{CO2}$ at $2349\space \mathrm{cm^{-1}}$ region For some other molecules (for example $\ce{CO}$) the peak separation corresponds to $2B$ (where $B$ is the rotational constant ...
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2answers
54 views

Thermochemistry: forms of energy & pressure

I've been in a few classes now that teach about energy, and I feel they're always so bad. There is always such a rush to start using equations to get problems solved, and I often feel I don't have an ...
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1answer
42 views

Amount of Energy Needed for Boiling a Litre of Water [closed]

What is the amount of energy (J or Wh) needed to boil one litre of tap-water in a regular kettle starting at room temperature (20°C)? The calculation itself assuming ideal and standard prerequisites ...
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0answers
31 views

How to store distilled water

How can I store distilled water without introducing impurities? I'm going to be doing so electrical studies of pure water and ice and I need a way of keeping the water pure during the experiments. ...
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1answer
81 views

How to calculate the solubility of AgCl in a MgSO₄ solution?

The solubility product of $\ce{AgCl}$ in water is given as $1.8\cdot10^{-10}$ Determine the solubility of $\ce{AgCl}$ in pure water and in a $0.25~\mathrm{M}$ $\ce{MgSO4}$ solution. I solve to the ...
3
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2answers
89 views

Stern Volmer Plot and calculating rate constant for quenching kq

I did an experiment irradiating benzophenone in UV light and worked out the rate constant for the reaction. Then I repeated the experiment using various concentrations of a quencher and worked out ...
4
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1answer
37 views

How many critical points? Why?

Critical points are defined (by wikipedia) as the "end-point of the phase equilibrium curve". I would say this diagram therefore has three critical points. But this is unnatural. I doubt its true. ...
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1answer
54 views

How much water evaporates In a vacuum before freezing?

I placed a container with 1000 grams (1 kg) of water at room temperature (20 degrees celsius) Inside a vacuum at 0.03 atm pressure. The water boiled for a few seconds then froze solid. I need to ...
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7 views

Given the Pair Correlation Functions for a Multi-component Fluid, is There a Simple way to Obtain the Helmholtz Free Energy?

I think it may not be possible. Given all the pair correlation functions, it seems possible to obtain the internal energy (assuming different species interact through pair-potentials (i.e. ...
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0answers
16 views

Estimating the protein concentration of an unpure protein solution

I'm confused on this problem for estimating protein concentration. Upon first glance, it looks like a simple Beer's law problem. but then there's the issue that the protein is not pure. How do I ...
2
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2answers
59 views

Anode and Cathode

I am very much confused: in simple voltaic cell ($\ce{Zn,~Cu}$ in $\ce{H2SO4}$), $\ce{Cu}$ is positively charged and is anode, where in Galvanic cell ($\ce{Zn}$ in $\ce{ZnSO4}$ and $\ce{Cu}$ in ...
2
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0answers
59 views

Relationship between thermodynamic reversibility and reactions

Often we're concerned with changes in thermodynamic properties during reactions, like $\Delta H_p = Q_{reaction}$ (change in enthalpy for an isobaric process). What seems odd to me is that in the ...
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67 views

Purity of precipitate in selective precipitation

An aqueous effluent contains 12 M Cd2+ and 10 M Mg2+ as solution of nitrates. Current practice is use NaOH to selectively precipitate the metals. (a) Is it feasible to get 0 Cd impurities in Mg ppt ...
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1answer
27 views

Does the catalyst alter the Potential energy Surface?

Catalyst provides alternative pathway to the reactants. Does it also mean that the potential energy surface is altered?
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1answer
38 views

What are the triple point pressure and temperature for pure cyclohexane?

Here is a video that demonstrates the interesting nature of the triple point of cyclohexane, so I tried researching on the internet for a phase diagram, but only found data from a manufacture where ...