New answers tagged

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The active chlorine, in %, is the mass-percentage of $\ce{Cl2}$ dissolved in the solution, without taking into account the fact that this $\ce{Cl2}$ may be at least partially transformed into $\ce{ClO-}$ or $\ce{HClO}$, according to one of the two equations depending upon the pH value : $$\ce{Cl2 + 2 OH^- -> ClO^- + Cl- + H2O}$$ $$\ce{Cl2 + H2O -> ...


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You cannot "apply" a property of a substance to another one. Unless it already has it too. Having said that: The $\ce{H2SO4}$ is an oxidizing acid because the $\ce{S}$ is in the $\ce{SO4-}$ anion is in a high oxidation state (VI). So when it reacts, the $\ce{S}$ will reduce to a lower oxidation state. Also, when it reacts it can produce nascent ...


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Hydrogen atoms need not bevunalterqbly acidic or non-acid for all time. Chemical reactions elsewhere is a molecule can change a hydrogen atoms acid-base reactivity Suppose you were to react acetoacetic acid, $\ce{CH3-CO-\color{blue}{CH2}-CO-OH}$, with a strong base such as a Grignard reagent. The base extracts the catboxyl proton, and that's it. In the ...


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From my answer: The IUPAC goldbook states that: "pyro" is used as a prefix designating compounds formed by heating a compound, usually with the elimination of water, carbon dioxide, or other simple molecule, e.g. pyroglutamic acid from glutamic acid. Since Pyroboric acid is made by heating boric acid, it is prefixed as pyro. You can also call it ...


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The short answer is that we'd like to do the first, but solving the multi-electron Schrodinger equation is impossible, so we use variations of your second option (ie considering many separate one-electron wavefunctions) to get something that matches experimental data as closely as possible, even though we don't ever get an explicit form of the true multi-...


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It basically comes down to molecular symmetry and since Buttonwood provided an answer just seconds ago, I'll leave the following as visualisations for it. An optimisation of $\ce{Fe2(CO)9}$ at the DF-B97D3/def2-SVP level of theory results in a D3h symmetric molecule. This in term results in degenerate vibrations (E') for the bridging $\ce{CO}$ at $\pu{1922 ...


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Despite the title of the publication, Fletcher et al. both present an IR spectrum of diiron nonacarbonyl in a matrix of ($\ce{Ar}$ + 10% $\ce{CO}$, recorded at $\pu{15 K}$) in the $\nu(\ce{C-O})$ region of about $2080 \dots \pu{1820 cm^-1}$ (left to right hand side) as below: (composite of two illustrations by Fletcher et al.) Given the data recorded, the ...


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The answer is a definitive affirmative yes. You don't need to reach out for proteins, organic dyes are known to suffer from solvatochromism in function of the polarity of the solvent they are dissolved. It either may be a bathochromic shift (or, red shift) of the UV-Vis absorption recorded, or a hypsochromic shift (or blue shift). In large proteins, you ...


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When we say that a metal falls below hydrogen in the electrochemical series, we typically refer to the oxidizing power of hydrogen ion at 1 molar concentration in water solution. The oxidizing power of concentrated sulfuric acid, forming sulfur dioxide and water when it reacts, could be greater than that of the aqueous hydrogen ions; if so, then ...


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Just because a metal can form complexes in different oxidation states with a given ligand, it does not follow that the complexes are equally stabilized in the different oxidation states by the same ligand. We often find that the relative stability of different oxidation states depends on the ligand environment. Copper, for instance, is stable only as copper(...


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I propose this simple graphic answer as a complement to the more thorough replies above (comments welcome to confirm validity of my answer). Trace pH Vs % [HA] and [A-]. 0% means you only have the acid [HA] and 100% you only have [A-]. Addition of acid or base, to the buffer solution, affects the ratio [A-]/[AH] and consequently, pH. This has been explained ...


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One of the best known examples is nitroglycerin, $\ce{C3H5N3O9}$, which has $18$ oxygen atoms in two molecules whereas only $17$ are required to oxidize all the carbon and hydrogen in those molecules. Not surprisingly: In its undiluted form, nitroglycerin is a contact explosive, with physical shock causing it to explode. If it has not been adequately ...


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As shown in the question, to fully oxidize one carbon and two hydrogen atoms you need three oxygens. Such a molecule, $\ce{HCOOOH}$, exists and it's called performic acid. It is used as a bleach and disinfectant and is explosive in high concentrations.


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Ammonium dichromate $\ce{(NH4)2Cr2O7}$ is well known for being able to burn with its own oxygen. If you dip a match into a crucible containing about $10\text{–}\pu{15 g}$ of ammonium dichromate, it will start to burn softly and throw out sparks like an active volcano, according to the equation $$\ce{(NH4)2Cr2O7 -> N2 + Cr2O3 + 4 H2O}$$ This operation is ...


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Disclaimer: None of this constitutes proof; it's just an informed guess. Any corrections with reputable sources are welcome. The simplest proposal seems to be single-electron transfer (SET) from $\ce{Cp-}$ to $\ce{Fe^3+}$. This forms the neutral cyclopentadienyl radical as well as $\ce{Fe^2+}$. This $\ce{Fe^2+}$ then reacts with any remaining unreduced $\ce{...


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Wet-oxidation of pyrite lead to iron(II) sulfate. $$\ce{2FeS2 + 2H2O + 7O2 ->[100 °C] 2FeSO4 + 2H2SO4}$$ iron(II) sulfate formed is eventually further oxidized to iron(III) sulfate, iron(III) oxide and iron(III) hydroxide. Note that the reaction is not that simple as it proceeds through many Fe(II) and Fe(III) intermediates: There are different proposed ...


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Typically, roasting sulfides leads to the generation of sulfur dioxide and metal oxide. In the case of pyrite, this may be described by $$\ce{4 FeS2 + 10 O2 -> 2 Fe2O3 + 8 SO2 }$$ The fire is needed to initiate the reaction. If well maintained, the heat generated by roasting may sustain the reaction. However, and especially for marcasite as an other ...


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Anions travel away from a cathode just partially, until there is built the counter potential gradient due charge displacement. When both gradients cancel each other, the migration stops. That happens when there is no ongoing electrolysis, e.g. if too small external voltage is applied. When there is ongoing electrolysis, the balance is continuously disturbed, ...


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Quoting Housecroft and Sharpe "Inorganic Chemistry" (second edition): "The blue, low-spin $\ce{[Co(H2O)6]^3+}$ ion can be prepared in situ by ...". Greenwood and Earnshaw says about $\ce {Co}^{3+}$ complexes "these are virtually all low-spin and octahedral" and "Even $\ce{[Co(H2O)6]^3+}$ is low spin". Thus $\ce{[Co(H2O)...


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Calculation from the FACT thermodynamics package suggests a mixture of about 80 mol% NaOH and 20 mol% NaI (sodium iodide) will melt below 250°C. Source


-5

The answer is FeCl2, which per Wikipedia: FeCl2 crystallizes from water as the greenish tetrahydrate, which is the form that is most commonly encountered in commerce and the laboratory. There is also a dihydrate. The compound is highly soluble in water, giving pale green solutions. You apparently have a reverse reaction observed in the normal REDOX ...


2

In principle, yes. In practice, it is much more complex (and you don't need to do it as others have already made the observations) The colour of a flame test is a consequence of the combination emission lines from electronic transitions in the flame. Most useful lines are narrow and involve transitions in isolated atoms between different electron orbitals. ...


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Prediction of color is different thing to prediction of emission spectrum, as the former is subjective. Even if we could accurately predict the radiometric emission spectrum, color evaluation, based on summary evaluation of photometric spectrum would be on experimental subjective assesment with multiple conclusions. Especially if women are involved. We men ...


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If you know the composition of any sample of compound, is it possible to predict it's flame test color? By current standards, unfortunately not. The calculations will be extremely complicated. If you recall, there are > 92 natural elements. The flame test works only for a few elements, so basically it is a useless test today. The Bunsen burner flame is a ...


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You are unclear if you are confused by $n$ itself, or by the particular notation $n(\ce{Na2CO3})$ $n$ is widely accepted to denote amount of substance, expressed in moles, as @Loong , IUPAC and Wikipedia say. If $n$ means the amount of the particular substance like $\ce{He}$ or $\ce{H2O}$, it is often written in index form like $n_{\ce{He}}$ or $n_{\ce{H2O}}$...


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There is another effect : relativity. In the 6th line of the periodic table (containing $\ce{Tl}$), relativity effect becomes important. Even though electrons have no velocity, their behavior does change as if outer electrons were moving at nearly the velocity of light. This was shown by Pekka Pyyko, Accounts of Chemical Research, Vol.$12$, No. $8, 1979$, p. ...


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Yes, the standardized quantity symbol according to ISO 80000-9:2009 Quantities and units — Part 9: Physical chemistry and molecular physics as well as the recommended quantity symbol according to IUPAC Quantities, Units and Symbols in Physical Chemistry (Green Book) for amount of substance is $n$. The quantity “amount of substance” shall not be called “...


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It can be explained by fajans' rules. As the positive charge on an atom increases its size decreases as a result polarising power increases. If polarising power increases then it distorts the electron cloud towards itself and hence ionic nature of the bond decreases. This is the reason why Thallium(I) chloride is more ionic than Thallium(III) chloride. ...


0

I am thinking of three methods, you could put the coin in a scanning electron microscope if it has a X-ray spectrometer attached and then get a spectrum of the X-rays which come off the coin. If you had access to a TRIGA nuclear reactor then you could try neutron activation combined with gamma spectroscopy. If you use a short irradation time in the reactor ...


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Isoelectronic means it has the same electronic structure and number of electrons, for example a negatively charged hydrogen ion (hydride) is isoelectronic with a helium atom. Now phosphorus forms a simple 3- ion which appears in solids such as aluminium phosphide, the phosphide anion is isoelectronic with an argon atom. If we count three atomic numbers ...


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Our current understanding of chemical kinetics is that all reactions with an activation energy are increased in rate by an increase in temperature. The question that is pertinent is "Which reaction is accelerated faster?". A temperature change at equilibrium influences the equilibrium and the overall composite rate. Whether the overall direction ...


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Typically, rates of uncatalyzed simple reactions increase with temperature. There are well-known examples where this is not the case (such as enzyme-catalyzed reactions where the enzyme denatures at high temperatures, or reactions with an intermediate that is at rapid equilibrium with the reactant in an exothermic step). In this case, if the $\ce{NaOH}$ is ...


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