DavePhD
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Can gaseous hydrogen and gaseous oxygen be compressed without reaction?
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The study Explosion Characteristics of Hydrogen-Air and Hydrogen-Oxygen Mixtures at Elevated Pressures includes data for pressures up to 200 bar. Data were collected for Hydrogen-Oxygen mixtures at ...

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What is the mass of 1 atom of carbon?
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9 votes

Both approaches are correct. Avogadro's number is $6.02214129\times 10^{23}$ and represents the number of carbon-12 atoms in 12 grams of unbound carbon-12 in the ground electronic state. $12$...

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Is most of the weight you lose actually released as carbon dioxide when you exhale?
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9 votes

Let's start with: How much is heat energy? 2000 kilocalories per day, considering $E=mc^2$, is $9.3 \times 10^{-8}$ grams is all the carbon released later when you exhale? No. Brainstorming,...

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How can 30 ml of water be heated in less than 10 seconds?
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Source: http://en.wikipedia.org/wiki/Nucleate_boiling As can be seen in the above graph, there is a local heat flux maximum for heating water, when the hot surface contacting the water is 30 degrees ...

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Is it possible to chemically treat grass to make it digestible?
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The indigestible component of grasses is cellulose, which is polymerized glucose. Yes, it is possible to hydrolyze the cellulose to glucose, which is of course digestible. The hydrolysis can be ...

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What's the type of bonding in La@C60?
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That the question says: "Without any 'binding' forces, the atom couldn't be possibly trapped inside the fullerene", shows you are misunderstanding fullerenes. Atoms such as Helium and $H_2$ can be ...

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What is the bond angle of water?
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In your comment, you say you are interested in "liquid water". The values in your self-answer are for gas phase water, and the second source is citing the first source, so it is really just one ...

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Why is water a poor solvent for organic molecules?
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Pure water can form two hydrogen bonds per molecule. The enthalpy of these hydrogen bonds is about 23 kJ/mol of water. You have to give water a very good reason to rip apart its hydrogen bond ...

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How is it possible to quantify the strength of a Lewis acid/base?
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$$\ce{A~ + :\!\!B -> \ \ A\!\leftarrow:\!\!B}$$ $$K_f = \dfrac{\ce{[A\!\leftarrow:\!\!B]}}{\ce{[A][B]}}$$ See sections 4.1 and 4.2 in the following reference for more information: http://...

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What is there in an atom between the nucleus and electrons?
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8 votes

It is not necessarily empty space. For example the flux of neutrinos on Earth is about $\pu{3E12 cm-2 s-1}$. At a given moment, a neutrino may or may not be within the atom or even within the nucleus ...

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Why does the phosphorus trifluoride molecule have dipole moment?
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Fluorine is more electronegative than phosphorus. The phosphorus is at the apex of a pyramid, the base of the pyramid being an equilateral triangle with a fluorine atom at each vertex. The F-P-F ...

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Why is proton coupling through bonds and how does this affect identical protons?
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How does a proton create a magnetic field that influences the neighboring protons (mainly) through bonding and not through space? Through space coupling is known as dipolar coupling and is actually ...

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Mechanism for interconversion of spin isomers of hydrogen
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The first question is: What is the mechanism by which spin isomers of hydrogen switch between the ortho and para forms? There is some explanation in ChemPhysChem 2006, 7 (3), 551–554 (non-paywall ...

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How to interpret the instruction of the dilution of hydrogen peroxide?
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Take $\pu{200 mL}$ of the $30\%$ solution, add water to a final volume of $1$ liter. Then you have a $6\%$ solution. Next, take $\pu{59 mL}$ of the $6\%$ solution and add water until it is $1$ liter. ...

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Calculating the volume of 1 mole of liquid water
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The molecule length value you are using is the problem. It is more like 300 pm, which is the van der Vaals diameter and includes regions where electron density is significant. You have calculated an ...

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Why is benzoic acid a stronger acid than 3-aminobenzoic acid?
8 votes

The $\mathrm{p}K_\mathrm{a}$ of benzoic acid is $4.2$. The $\mathrm{p}K_\mathrm{a}$ of aniline (aniline's conjugate acid really) is $4.8$. The two macroscopic $\mathrm{p}K_\mathrm{a}$s of 3-...

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How to calculate the 15 geometrical isomers of an octahedral complex with all ligands different?
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Assign "a" to one of the six equivalent positions. Note that there are now 5 choices (b,c,d,e,f) for the opposing position. You are left with four equivalent equatorial positions. Once a ligand ...

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What's the difference between radial probability and probability density?
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Probability density is probability per volume. Probability density at a given point means probability per volume in the limit that the volume is infinitesimally small. Radial probability ...

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Are all solutions of weak acid/bases buffers?
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The term "buffer" implies a purpose of resisting changes in pH when small amounts of acid or base are added. The buffer will be most effective when the pH equals the pKa of the acid. This is when ...

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Synthesis Golf I: Sodium Fluvastatin
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Reference through step 2: Synthesis of carbon–14 labeled fluvastatin, Journal of Labeled Compounds and Radiopharmaceuticals volume 41, pages 1-7. Step 0 (product is commercially available): ...

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Covalent and Ionic Bonds
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If you are asked on a test "Is sodium nitrate ionic or covalent?", say "ionic" and if given the opportunity, justify your answer with electrical conductivity of molten sodium nitrate and aqueous ...

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Periodic table for printing
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The IUPAC periodic table (2016-pdf) is good because it quantifies the accuracy of the natural abundance atomic weights, but it doesn't give electron configuration. The NIST periodic table has ...

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Why do tetrahedral complexes have approximately 4/9 the field split of octahedral complexes?
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The ratio is derived in The angular overlap model. How to use it and why J. Chem. Educ., vol. 51, page 633-640. First, relative expressions (Shaffer Angular Overlap Factors) are derived for overlap ...

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Is a highly oxidized element more electropositive than a lesser oxidized counterpart?
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There are two definitions of electropositive: 1: charged with positive electricity 2: having a tendency to release electrons The author is using the first definition, while you are thinking ...

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Why is vulcanization called "vulcanization"?
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According to Thomas Hancock's 1857 Personal narrative of the origin and progress of the caoutchouc or india-rubber manufacture in England In preparing to carry out the new process on a large ...

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What is the Ka of OH- and Kb of H3O+?
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8 votes

For $\ce{O^2-}$, the $\mathrm{p}K_\mathrm{b}$ is approximately $-22$, so the $\mathrm{p}K_\mathrm{a}$ of hydroxide is about $36$. sources: http://www.newworldencyclopedia.org/entry/Oxide and https://...

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Old sample of sodium tetraphenylborate—why it is red?
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According to Decomposition of Sodium Tetraphenylborate, which relates to the Savanna River site for nuclear weapons material production, Stable aqueous NaTPB solutions are a transparent, flesh-...

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How chemically homogeneous is air?
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Oxygen/nitrogen ratios vary seasonally and geographically even at sea level on the order of 200 ppm. Oxygen concentration has also been slowly decreasing in correlation with carbon dioxide increase. ...

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Have there been no advances in the determination of effective nuclear charges since Clementi and Raimondi in the 60s?
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Analytical Dirac-Hartree-Fock-Slater screening function for atoms (Z=1–92) Phys. Rev. A 36, 467 seems to address the deficiencies mentioned in the question. Effective nuclear charge is expressed ...

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What is an orbital boundary surface?
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It means that the boundary surface is a closed surface or set of closed surfaces, such that there is a 90% chance that an electron is interior of the closed surface and a 10% chance that the electron ...

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