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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Cathode region in corrosion

The anode region is on the iron where the following reaction occurs: $$ Fe_{(s)}\rightarrow Fe^{2+}_{(aq)}+2\,e^- $$ and at the cathode region, the following reaction occurs $$ ...
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38 views

How does light get refracted through five lenses in a component of a spectrometer? [on hold]

Question three in my Pre-lab questions for my Physical Chemistry practical is causing me problems. If a parallel beam of light hits the first lens with focal length 2F it will cause the light to ...
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3k views

Hypothetical: What happens to water as pressure increases to infinity?

I've asked a similar question here but the answer given shows the behaviour of water under general conditions. I'd like to know what the behaviour of water is like as pressures increase towards ...
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1answer
26 views

Rotational states of a molecule

How can you determine the possible rotational states of a molecule? Atkins Physical Chemistry book says that for linear molecules there are two possible rotational states, but what is the general ...
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1answer
27 views

Do liquid O2 and N2 form ideal solutions?

I suspect they do, but could not find data on this. (I mean at temperatures near those used in the distillation of liquid air.)
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37 views

Nuclear Spin Multiplicity of radicals

How do you calculate the nuclear spin multiplicity of radicals such as N2H+? How does the net charge on the molecular species effect its overall nuclear spin?
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35 views

Can there be more than one combination of reactant/product concentration for a specific equilibrium constant?

For an elementary reaction like $$\ce{A + B -> AB},$$ $$K_{c} = \frac{\ce{[AB]}}{\ce{[A][B]}}$$ and $$\frac{\mathrm{d}\ce{[AB]}}{\mathrm{d}t} = k\ce{[A][B]}.$$ If I let the reaction reach ...
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86 views

What is 'equality' of chemical bonds?

I was trying to solve a test series and I saw this question: "Why all $\ce{C-O}$ bonds in $\ce{CO_3^2-}$- are equal but not in $\ce{H2CO3}$?" I am completely confused by this question.
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44 views

Why is CO a major species only in fuel-rich combustion?

In fuel-rich combustion, my understanding is that enough fuel reacts and consumes all of the oxygen present. The combustion products $\ce{CO2}$ and $\ce{H2O}$ undergo dissociation until equilibrium is ...
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35 views

Femtosecond spectroscopy

Hi I am new to laser pump-probe spectroscopy and want to understand the concepts better. At the moment I am struggling to understand the following: When one takes absorption measurements with lasers ...
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1answer
47 views

How do I write the deterministic rate equation for bimolecular reaction with similar particles?

I was wondering how to write down the deterministic rate equation for a bimolecular reaction with similar particles. e.g. $$ \mathrm{A \overset{k_+}\rightarrow B +B}$$ and $$\mathrm{B +B ...
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63 views

Is There a Difference in the Definition of Complete and Stoichiometric Combustion?

My question has to do with some combustion related definitions. When the term complete combustion is used, is it assumed that the combustion is stoichiometric (reactants combine perfectly), but ...
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51 views

Calculating energy level from wavelength

The transition of an electron from a higher level to a lower level results in the emission of a photon of wavelength 350.0 nm. If the energy of the higher level is -3.24 x 10-19 J, calculate the ...
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31 views

How to efficiently reduce of ilmenite to pure titanium?

I am looking for a process in which reduces ilmenite to pure titanium with the highest yield possible. We are to use a process of our choice or one that we have created in conjunction with FactSage to ...
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35 views

How to determine an unknown gas in a tube with a massless piston at equilibrium conditions?

There is a massless piston that can move freely in a horizontal tube that is closed at both ends. To the left, there is a sample of helium gas at $300~\mathrm{K}$ and $4~\mathrm{atm}$. To the ...
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1answer
67 views

Explaning Cis & trans isomers through VSEPR

Total rewrite as was a panic-stricken 2am question. Unfortunately I wrote on an application that VSEPR theory is a reason of Cis-Trans isomerism (specifically in fatty acids however I doubt that ...
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1answer
45 views

Boundary lines in phase diagrams and the lever rule

My first question is: What exactly happens on a point situated on a line? Or on a point such as E in this figure? Does point E mean that the $\delta , \gamma + \delta , \delta + \epsilon , \gamma + ...
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1answer
37 views

Transfer of energy

After completing a lab for my chemistry class I am finding it difficult to find the initial temperature of an iron nail after being heated. Procedure of the lab went as follows: heat an iron nail, ...
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1answer
41 views

What is this equation for?

I have been given a formula on the topic of alloys and temperature, however am unsure specifically what this equation calculates. The equation is as follows: $xC_{1} + (1 - x) C_{2} = C_{3}$ I am ...
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2answers
61 views

If the equilibrium constant in a reaction is greater than 1 is it possible that there are more moles of reactants than products?

I'm wondering if this is possible because could there not be a situation in which the reactants were pure solids/liquids and would therefore not contribute to the value of k but still contain more ...
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1answer
63 views

Calculate the degree of dissociation of AlCl3

I'm having trouble figuring out where to go with this question. Calculate the degree of dissociation of $\ce{AlCl3}$ if molar conductivity of the solution is $31.3\ \mathrm{mS\ m^2\ mol^{-1}}$ and ...
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4answers
111 views

Storage of Urine

Not all may be favorable to this project, but I will explain what I am trying to do. I work at home, and instead of walking a moderate distance to the bathroom and loosing my focus, I've been, at ...
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1answer
35 views

What is the difference between organosilyl, alkoxysilane and silane compounds?

What is difference between organosilyl, alkoxysilane and silanes? How do these groups make a surface hydrophobic?
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18 views

Dissociation of water into H+ and OH-: Does the law of mass action hold at nanoscale?

Suppose water under neutral conditions is confined in a virtual spherical nanocontainer with a radius of 25 nm. To calculate the number of hydronium ions, one uses water dissociation constant which is ...
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23 views

Elastic scattering of x rays in 3D: the principle for XRD analysis

I have some trouble visualising scattering of x-rays in 3D, since all textbooks and examples present it in 2D. Under I will share some reflections (no pun intended) about the elastic scattering of x ...
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80 views

What's the difference between normal and formal charge?

From what I know, even at the brink of completion of my highschool chemistry course, I'm not clear about it. My thinking: I know that normal charge is actually the charge due to electron transfer ...
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4answers
64 views

Gas phase chiral molecules

Are there any molecules that are chiral that are also gases at room temperature? Failing that, what chiral molecules have a high vapor pressure? Propylene oxide has a boiling point of only 34 C, so ...
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49 views

What should the Rehm-Weller equation look like?

The Rehm-Weller equation, which defines the energy change for photoinduced electron transfer according to Lakowicz "Principles of Fluorescence Spectroscopy" should look like: $\Delta ...
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1answer
50 views

Chemistry and mathematical modelling

I'm searching for a chemical daily life experience that can be modeled by superior mathematics so that the origin of the equations involved can be easily explained to a beginner in chemistry. By ...
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1answer
99 views

Why is active mass of a pure solid or liquid always taken as unity?

Active mass is defined as the molar concentration ie. number of Gram-moles per litre. My book then wrote Active mass of pure solid/liquid is always 1 . The book reasoned that Molar ...
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1answer
59 views

Net charge of Peptides at pH1 and pH0

Taking Glycine and aspartic acid. As both the amino acids are fully protonated at pH 0 ad pH 1, how does the peptide bond form? Is it a two step mechanism where the OH from an alpha carboxyl group ...
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1answer
37 views

Acid-Base Titration: Do Acids and Bases Have the Same Coefficients of Moles if They Neutralize One Another?

The questions states: Ammonia has the formula NH3. Household ammonia is a dilute aqueous solution of NH3. Aqueous ammonia is a base that can neutralize acids. If 18.2mL of 0.800 M HCl solution are ...
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34 views

Application of Grahms Law of diffusion

$\ce{H2}$ (di-hydrogen) and $\ce{He}$ are kept in a container at partial pressure $p_1$ and $p_2$. A thin perforation is made in the wall of the container and it is observed that both gases diffused ...
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35 views

Is there a heat capacity of an object when it is melting?

Is there a heat capacity of an object when it is melting? I'm questioning it since the temperature doesn't change during phase transitions and the units of heat capacity is Joules/Kelvin.
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52 views

Why is the Standard enthalpy of formation of O2 and other reference forms of element zero?

Well, from what I know bonding releases energy. And does anybody know a source for finding the reference form of element at standard conditions?
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1answer
34 views

How are cathode rays produced?

Why cathode rays are produced if pressure of the gas discharge tube is lowered to about $10^{-4}$ atm? How bombardment of glass of gas discharge tube from cathode ray result in a faint glow?
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1answer
41 views

Does Combining Solid/Liquid Concentration with $K_c$ Matter when Comparing $K_c$ of Different Reactions?

I know it is convention to take liquid/solid concentrations as constants and lump it with the equilibrium constant. However, if we were trying to compare the equilibrium constants of two different ...
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37 views

How do I calculate the molar mass of an unknown gas?

A piston is placed in a closed tube. To the left, there is Hydrogen Gas at 400K and 4 atm. To the right, there is an unknown gas at 200K and 2 atm. At equilibrium, the piston is at 1/3 of the length ...
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2answers
39 views

Grams to volume question?

How many liters of $\ce{H2(g)}$ at STP are produced per gram of $\ce{Al(s)}$ consumed in the following reaction? $$\ce{2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g)}$$ Express your answer to four ...
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0answers
52 views

Molecular bond angles

How do Bond angles vary in molecule with a lone pair and central atom of different electronegativity, but in the same period so that ecectronegativity matters more than orbital size? Assuming that the ...
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1answer
22 views

Confusion with Law of Equivalence

Law of Equivalence states that One equivalent of an element combines with one equivalent of the other. Equivalent of $\ce{Na}$ is $22.99$ & that of $\ce{0}$ is $8$. By the Law of ...
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1answer
46 views

Bond Dissociation Temperatures for Hydrocarbons

I'd like to know the temperatures that various hydrocarbons such as methane, butane, and propane, etc. will dissociate into hydrogen and carbon. Is there a reference where I can look up these ...
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1answer
41 views

Element letters

Does it change the compound if the element letters are switched? ex. HO or OH. Are those two different compounds or are they one in the same? This may be a simple question or I may have incorrectly ...
2
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1answer
72 views

What is the entropy of mixing of two ideal gases starting out with different pressures?

The entropy of mixing of ideal gas is given by this equation: $\Delta S_{mix} = -nR(x_1\ln x_1 + x_2\ln x_2)$ Does this equation works only when the initial conditions of both compartments are at ...
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41 views

Relationship between Auto-Ignition Temperature with Pressure and Fuel

Experimentally it appears that increase in pressure, fuel concentration, and chain length causes AIT to decrease until a minimum where even further increase in these parameters increases the AIT. ...
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1answer
87 views

Additional Questions Regarding Free Energy Requirements for Reacting Gases

Continued from my previous question here. With regards to the Boltzmann factor, I am confused on what type of terms we can substitute for E. I know kinetic energy is one, free energy as well, but ...
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1answer
183 views

Why do we use dG < 0 to describe a spontaneous process?

With something like a reaction or phase change, all sources use the criterion that $dG < 0$ for the reaction to be spontaneous and then substitute an appropriate expression for $dG$ to the specific ...
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1answer
39 views

Orbital angular momentum

For hydrogen atom, L^2 and Lz can be obtained as eigenvalues for a particular wave function. But that does not completely specify the angular momentum vector. How to get about this problem? Also, in ...
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71 views

Confusion about the relationship between free energy and kinetic energy for reacting gases

I am confused about the energies we are talking about when speaking in regards to the Maxwell Boltzmann Distribution and activation energies. Is there an relationship between kinetic energy and ...