New answers tagged

0

You should probably be cautious using bond dipoles to predict molecular dipole moments, and it does seem ad hoc if not downright flimflam to invoke a dipole to the nitrogen lone pair. Now if you read the wikipedia page on nitrogen trifluoride, it explains that NF3 is slightly soluble in water without undergoing chemical reaction. It is nonbasic with a ...


-2

The answer lies in electronegativity. When a proton attracts an electron, the electron doesn't magically suck out the charge of the proton. The proton's charge is still distributed in all directions. The reason why 1 proton on average can attract only 1 electron is because electrons push each other out. Now let's first take H - it has 1 proton which ...


3

An atom is only neutral when viewed as a single object from large enough distance. But as an electron comes closer to the atom, it "notices" the electron cloud first. This cloud also "notices" the electron and deforms—the atom polarizes—so as to keep the atomic electrons farther on average from the extra electron, since like charges repel. But this ...


1

We know now that bromine can be stored safely in glass (with appropriate glass handling, of course). Now for the "brown" part. Bromine can break down on exposure to ultraviolet light, a reaction shown here as part of an alkene bromination. Uncontrolled, this process could release reactive atoms; these may degrade surrounding materials and the products ...


1

TLDR: There is no exact generalized reaction. The reaction depends on type of interhalogen compound(value of n) and the nature of metal halides(ionic or covalent) $\ce{XX^{'}}$ form Let us take iodine monochloride($\ce{ICl}$). If it is reacted with ionic chloride like $\ce{KCl}$, it will form $\ce{ICl2-}$ ion. $$\ce{MCl + ICl -> M+ICl2-, (M=K, Rb)}$$ ...


0

All interhalogen compounds are prepared by direct combination of elements, and where more than one product is possible, the outcome of the reaction is controlled by temperature and relative proportions of the halogens. For example, reactions of $\ce{F2}$ with the later halogens at ambient temperature and pressure give $\ce{ClF, BrF3}$, or $\ce{IF5}$, but ...


4

I assume liquid halogen to be bromine. From here: Glass, ceramic nickel or lead containers are suitable for bromine. Lead-lined steel tanks can be used. Only highly fluorinated plastics will resist corrosion. A free space of 8-10% by volume should be left in the container. Also see: https://patents.google.com/patent/US3375077


2

The ozone molecule is described with two resonant structures(as in figure) in which all the oxygen atoms respect the octet rule. The oxygen in the middle has a positive charge because has only 5 valence electron and the oxygen with the single bond has a negative charge because it has 7 valence electrons. In the real molecule both the bonds have the same ...


2

It's hard to pinpoint what the problem here is since I don't have the mentioned book to compare an answer with. The simplest way is write down half-reactions for reduction (red) and oxidation (ox) processes once you've assigned oxidation numbers (denoted above the symbols of the elements which are participating in a redox reaction), then balance the number ...


9

A short “obligatory” reference from IUPAC Recommendations [1, p. 21], section IR-2.2.3.1 regarding use of parentheses in formulae: (d) In solid-state chemistry, to enclose symbols of atoms occupying the same type of site in a random fashion. The symbols themselves are separated by a comma, with no space. Example: K(Br,Cl) Related question ...


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Quoting from here: In accord with general usage, the comma "," should be used to indicate continuous substitution, partial as well as complete, if there is no change of CN. Vacancies (symbol ") are treated here just like atoms. This usage is restricted to chemical formulas for atoms on a specific site. The comma is not appropriate for structure ...


3

I have seen this nomenclature used as a shorthand to indicate a solid solution of two different ionic compounds that share a common anion. For example: https://www.ncbi.nlm.nih.gov/pubmed/22011346 and: https://www.sciencedirect.com/science/article/pii/S0016703714004888 Since it's a solution of two different compounds, its composition can be variable.


3

There are many ways to synthesize copper selenide. It generally has two forms $\ce{Cu2Se}$ and $\ce{CuSe}$ but actually it is a non-stoichiometric compound. They are grown as nanoparticles for various applications like making semiconductor, optoelectronic components, sensors etc. By direct combination of copper and selenium vapour / direct displacement of ...


0

Every 3 moles of Ag reacts with 4 moles of Nitric acid. Therefore the mass ratio is: $$ \frac{m(Ag)}{m(HNO3)} = \frac{3}{4}\frac{MM(Ag)}{MM(HNO3)} = 1.28 $$ MM is molar mass(g/mol)


1

The bond angle in $\ce{PH3}$ is about $92-93^\circ$, and by the percentage $s$ character formula i.e $\cos(\theta) = s/(s-1)$ you can calculate the $s$ character and that comes out to be 6%. And that where drago rule holds true , that is the orbitals involved in bonding are pure $p_x$ ,$p_y$, $p_z$ and as a character is high the lone pair is present in pure ...


-1

They don't exist because they are not energetically feasible. I also think that what is represented at http://iron.atomistry.com/ferrous_sulphite.html is mostly wishful thinking. Each "reaction" supposedly producing FeSO3 can be represented by an equilibrium which lies farther to the left.


3

Option C is correct. You could start by looking up the definition of a coordinate bond. Here's a tiny excerpt from the above link: A coordinate bond is a kind of 2-center, 2-electron covalent bond in which the two electrons derive from the same atom. In your case, as you have correctly noted yourself, the $\ce{NH3}$ molecule will have an "lone pair" of ...


3

As pointed out by @Paul in case of the reaction between 2 hydrogens atoms you need a third body to take away the excess energy. This third atom(M) can be another hydrogen molecule or other inert gases(eg. Ar, He, N2). Or you can have the presence of a wall(eg. gas-phase hydrogens atoms in a container): Another possibility is adding a reactive gas(eg.oxygen)...


4

It may depend on who you ask, and maybe even when you ask. The tl, dr of what is below is that we are moving towards counting scandium as a transition metal. Wikipedia follows the IUPAC definition and accepts the label for scandium because it forms atoms with partially filled $d$ orbitals, and also copper because it forms ions with partially filled $d$ ...


1

One problem is there is not enough voltage for this thing to sell. Say you have molar acid and 1 molar base, both strong and both functioning as ideal solutions. Thermodynamically you have one electron transfer associated with the net reaction $\ce{H^+}_{aq}+\ce{OH^-}_{aq}\to\ce{H2O}$ and the equilibrium constant is $10^{14}$ at room temperature. Put ...


2

Since $p_\ce{CO2}$ is $\pu{30 mmHg}$, and we are given the $0.03$ of $\frac{\pu{mM}~\ce{CO2}}{\pu{mmHg}~\ce{CO2}}$ ratio, we can calculate the concentration of the $\ce{CO2}$ in plasma. $$\pu{30mmHg}~\ce{CO2}\times 0.03\frac{\pu{mM}~\ce{CO2}}{\pu{mmHg}~\ce{CO2}}= \pu{0.9 mM}~\ce{CO2}$$ $$\ce{CO2 + H2O \xrightarrow{\text{carbonic anhydrase}} H2CO3}$$ $$\...


1

We know that the planes (h k l) are the planes which are perpendicular to the vector (h, k, l). Thus, their equations are: $$hx+ky+lz=D$$, in which D is a real number. But these planes have to pass through atoms of the crystal. So, $$D=na$$, where a is the lattice parameter and n is a natural number (e.g., 1, 2, 3, ...). So, the planes have the equation: $$...


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The single most important factor is strength ( mechanical compressive ); coal is heated to make coke, the resulting coke is stronger than the original coal. Also, coke helps to make the charge of iron oxides and limestone more porous to permit gas flow up and droplets of liquid iron and slag down. The coke oven heating drives off volatiles from the coal, ...


2

Reciprocal space One way to derive the formula is to use reciprocal space coordinates. The reciprocal space lattice has three unit cell vectors, a*, b* and c*. The diffraction vector d* is given by: $$d^* = h a^* + k b^* + h c^*$$ The d-spacing is given by the reciprocal length of d*. The relationship between direct space and reciprocal space unit cell ...


2

For a phosphate buffer with $\mathrm{pH} = 7,$ the two dominant species are $\ce{H2PO4-}$ and $\ce{HPO4^2-}$. The relevant $\mathrm{p}K_\mathrm{a}$ is $7.2$ (this is $\mathrm{p}K_\mathrm{a2}$). From the Henderson-Hasselbalch equation, using $\mathrm{pH} = 7,$ the ratio of $\ce{HPO4^2-}$ to $\ce{H2PO4-}$ is about $0.631.$ You can see this in the alpha diagram ...


1

This particular question is testing basic knowledge of buffers. In the most simplest explanation possible, a buffer will resist changes in pH the best when the pH is at the pKa. In the case of phosphoric acid, there are three acidic protons thus making three pKa values. Pulling the following table from Wikipedia $\hspace{3.25cm}$ We can see $pK_{a2}$ is ...


3

You might want to check your units. The energy should be in J/mol, according to the values you put in, and not in kJ/mol. $e^{-22200/(8.314*298)} = 0.000128397 \approx 1.3*10^{-4}$


1

The $\mathrm{p}K_\mathrm{sp}$ value of $15.69$ for $\ce{HgCl2}$ given by your reference must have an error. First of all, $\ce{HgCl2}$ is fairly soluble in water at $\pu{20 ^\circ C}$. Wikipedia lists it as $\pu{65.7 g L-1}$, yet lists solubility of $\ce{Hg2Cl2}$ as $\pu{3.25e-4 g L-1}$. Meantime, I found an University of Arkansas, Little Rock website, which ...


4

Historically, the term ferromagnetism was used for any material that could exhibit spontaneous magnetization: a net magnetic moment in the absence of an external magnetic field (Wikipedia). However, in 1948, Louis Néel showed that there are two levels of magnetic alignment that result in this behavior (Ref.1): One is ferromagnetism in the strict sense, ...


10

I believe GATE is a university entrance exam in India, so they will not expect you to solve an extremely complicated equation to predict ferromagnetism or to memorize an infinite list of substances. Sadly, there is some element of rote memorization still lingering like a pest in the educational testing system. Good news for you is that relatively few ...


2

Color is related to how the compound absorbs light. For example, highly unsaturated compounds (e.g. beta-carotene) will absorb green to blue light, and thus reflect red and yellow. This is why it appears orange. Somewhat unsaturated compounds (e.g. containing an aromatic ring), on the other hand, mostly absorb UV light and reflect all visible light; they ...


1

It appears that Sørensen was the first to publish the synthesis of trioxalatocobaltate(III) trihydrate [1]. A summary written in English (and that should answer both of your questions) including chemical reactions can be found in the very first volume of Inorganic Syntheses1 [2, p. 37]: C. POTASSIUM TRIOXALATOCOBALTIATE $$\ce{K3[Co(C2O4)3]·3H2O}$$ ...


0

In the first step, one makes an oxalate complex by decomposing the carbonate salt of cobalt (II) with oxalic acid. I am not sure how an oxalate salt will decompose the carbonate to carbon dioxide. Oxalate ion makes a complex. The second step is lead dioxide oxidation. See this book chapter for proper synthesis equations of cobalt (III) oxalate complex, ...


2

The thermodynamic equilibrium constant $K$ (different from both $K_p$ and $K_c$) and the reaction quotient $Q$ are defined with reference to a standard state. When all reactants and products are at standard state, $Q = 1$. $K$ and $Q$ are related to the Gibbs energy of reaction via: $$\Delta_\mathrm{r}G = RT \ln\frac{Q}{K}$$ No matter which standard state ...


1

$K_c$ is the equilibrium constant for reactions where reactants and products are all in the same phase, which is the case for your reaction. The subscript c implies that $K_c$ is expressed in terms of concentration, which has units of moles per volume. I'm not entirely sure on this, but I don't believe you can use partial pressures in the expression for $K$, ...


1

Well maybe I'm an idiot, but I also get a different result. First of all, the equilibrium constant is given by $$ K = \frac{\prod_p a_p^{m_p}}{\prod_r a_r^{n_r}} \,, $$ where $a$ is the activity of a reactant/product, $p$ is the index for products, $r$ is the index for the reactants, and $m_p$ and $n_r$ are the corresponding stoichiometric constants. So ...


1

You should not use calcium as an indirect means to evaluate your vitamin D status. While both are metabolically connected different mechanisms are involved meaning that there is not a one directional correlation across time, and many other things, unrelated to vitamin D, affect blood calcium levels as well. In the short run, all else kept equal (which is a ...


0

If there is an element in the reactants and it is not an element in the products then yes, oxidation or reduction has occurred. Acid-base reactions are pretty much non-redox reactions. But it is always handy to learn the oxidations numbers. Extra sources Do non-redox reactions exist?


4

Strictly speaking, the answer depends on conditions and, as a consequence, states of aggregation. Reaction (1) can be reversible if iron(II) sulfide is subsequently heated above $\pu{700 °C}$ in vacuum to prevent oxidation of the elements [1, p. 422]: $$\ce{FeS(s) ->[\pu{700 °C}][vac] Fe(s) + S(g)}\tag{1a}$$ Reactions \eqref{rxn:2a} and \eqref{rxn:3a} ...


2

IUPAC “Green Book” recommends to use $\mathrm{sln}$ for denoting a solution in general [1, p. 54], referring to earlier Recommendations 1981. Appendix No. IV to Manual of Symbols and Terminology for Physicochemical Quantities and Units [2, pp. 1240–1242]. This has been extensively covered in the following posts: What is the standard way to denote physical ...


-3

We call this weird thing as back bonding. The lone pair kinda delocalises or seeks refuge in the empty d orbital of Si, basically providing each N-Si, bond, on an average, a one third of an extra bond.


9

In appears that the synthetic procedure for preparation of iron(II) oxide from iron(II) oxalate has been first described by Günther et al. [1] and subsequently summarized in Brauer's Handbook of Preparative Inorganic Chemistry [2, p. 1497]: Iron (II) Oxide I. $$\ce{\underset{143.8}{FeC2O4} = \underset{71.8}{FeO} + \underset{28.0}{CO} + \underset{...


3

The paper linked below indicates that the proper temperature is north of 535°C. This decomposition should be carried out with great caution though as some of the products might enflame, or even initiate a thermite reaction if carried out in the presence of Aluminum (as in the experimental setup used for the paper hereafter). Source: https://pubs.rsc.org/en/...


2

Graphite is elemental carbon, and carbon is unstable in the presence of oxygen because they react to form carbon dioxide. The rate of this reaction: $\ce{C + O2 = CO2}$ is very slow and has a high activation energy, so a piece of graphite can sit in oxygen at room temperature for millions of years without anything happening to it. Once temperature increases, ...


40

The $\mathrm{pH}$ of pure water (rain as well as distilled water) in equilibrium with the atmosphere ($p_{\ce{CO2}}= 10^{-3.5}\ \mathrm{atm}$) can be calculated as follows. $$[\ce{H2CO3^*}]=K_\mathrm H\cdot p_{\ce{CO2}}$$ where $[\ce{H2CO3^*}]$ is the total analytical concentration of dissolved $\ce{CO2}$, i.e. $[\ce{H2CO3^*}]=[\ce{CO2(aq)}]+[\ce{H2CO3}]$, ...


9

Under atmospheric pressure, dissolved carbon dioxide can reach an equilibrium state in water that yields a pH of as low as 5.7


16

You are forgetting an important component of the air: carbon dioxide. When it dissolves in pure water (=rain water), it makes it acidic. It is not considered that harmful. Acid rain has a negative connotation; it is mainly caused by anthropogenic activities. The low pH of acid rain is due to sulfur oxides and nitrogen oxides and it is indeed below 5.7. ...


2

To illustrate Oscar's answer further, it should be noted that boron, despite existing in more than ten allotropic modifications, is in general quite chemically inert (especially in crystalline form). For example, boron doesn't react with hydrogen directly and all boranes are synthesized by other means. Although boron may be oxidized by fluorine at room ...


5

Having actually perform this reaction, I can say with certainty that when you mix aqueous sodium bicarbonate with aqueous magnesium chloride, there is no apparent reaction. This is consistent with an equilibrium reaction (actually, just ions): $$\ce{2 NaHCO3 + MgCl2 <=> 2 NaCl + Mg(HCO3)2}$$ However, upon brief heating in a microwave (for example), ...


0

Specific for your compound you find at least two public IR spectra, either in KBr: (source) or from one of the larger chemical vendors as .pdf (source, Sigma-Aldrich, product number 305553, CAS-RN 68915-31-1) More generally speaking for phosphates, you equally find some related entries in NIST webbook chemistry here, too. For IR-spectra in general, ...


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