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Questions tagged [molecules]

An electrically neutral entity consisting of more than one atom (n > 1). Rigorously, a molecule, in which n > 1 must correspond to a depression on the potential energy surface that is deep enough to confine at least one vibrational state. This tag should be applied to question about certain molecules or a class of them.

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How can I tell if a molecule is polar or not?

Consider $\ce{PCl3}$, $\ce{CH2Cl2}$, $\ce{HCN}$, and $\ce{SiO2}$. Which of these molecules are polar substances? I appear to be lacking on the concept of "polar substance". I was just studying about ...
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Why is water transparent?

Some substances like copper sulfate for example have vivid colors. But why is water transparent? Does it not emit any visual light from the electromagnetic spectrum?
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Are there gases that spontaneously combust when mixed with oxygen? [closed]

Is there a known gas that would combust by there mere action of mixing with oxygen? So, we could put this hypothetical gas in a balloon, and if the balloon popped, it would combust and explode.
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Are difluorine and hydrogen chloride considered isoelectronic?

Why are $\ce{F2}$ and $\ce{HCl}$ not considered isoelectronic? Both have 18 electrons. $\begin{align} \ce {H}\!:&\ \ce{1 e-}\\ \ce{Cl}\!:&\ \ce{17 e-}\\ \ce{F}\!:&\ \ce{9 e-}\\ \end{...
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Proper typography of “NOx”

I am a journal typesetter, and recently I came to a problem that I'm not sure I know to solve. The question is how to properly typeset the "NOx" abbreviation for nitrogen oxides. Which is ...
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If you can smell something does that mean that this thing loses molecules?

When you can smell something there must be some molecules in your nose which signalize the smell in your nose. Does that mean, that e.g. a cheese is losing molecules which fly into your nose? And does ...
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How to understand the concept of moles? [duplicate]

I have trouble relating to the mole concept. For example in a question like the following: How many moles of $\ce{K}$ are in 1 mole of $\ce{KOH}$? How is it that in 1 mol of $\ce{KOH}$ there ...
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Why is tetrafluoromethane non-polar and fluoroform polar?

Consider the Lewis dot structures of the molecules fluoroform, $\ce{CHF3}$, and tetrafluoromethane, $\ce{CF4}$:   My first line of thought is that both of these molecules are symmetrical (the ...
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Why is the discovery of chiral molecules in space a big accomplishment?

Today, I came across the discovery of a chiral pair of molecules in interstellar space. I know that a chiral molecule is a molecule that is not superimposable on its mirror image. But why is this ...
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Calculating the volume of 1 mole of liquid water

I am doing some rough calculations to test my understanding of elementary chemistry. In what follows, I calculate the volume of one mole of liquid water at about $\pu{4 ^\circ C}$ and $\pu{1 atm}$: ...
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What is “mineral spirits”?

I'm working in a project, and for a specific thing, I need to work on a possible recovery of $\ce{HCl}$ in aqueous phase. I found a patent on the net in which they use an amine to make a complex with $...
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1answer
859 views

Discrete molecules [closed]

I came a across a passage in my textbook on Formula Mass topic which mentioned something about discrete molecules. Some substances such as sodium chloride do not contain discrete molecules as their ...
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1answer
139 views

How do I visualise bicyclo[4.4.1]undeca-1,3,5,7,9-pentaene?

While reading my organic chem book, I came across this compound: Since this is an exercise question, I do not know the name of this compound. I am unable to visualize this compound (how it looks out ...
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1answer
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Is a non-compound molecule a chemical substance?

The Wikipedia definition of chemical substance states: A chemical substance, also known as a pure substance, is a form of matter that has constant chemical composition and characteristic properties....
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How to explain the periodic trends in boiling points in groups?

Observing the trend of boiling points of the compounds listed, choose the appropriate terms to fit into the blanks: \begin{array}{lr} \text{Compound}& \text{boiling point}\\\hline \ce{H2Te} &...
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Electron density definition of single, double, triple bonds?

I was reading this question and the answer by user EricBrown to it, and this got me thinking about covalent chemical bonds. The way I was always taught is that a single bond contains 2 paired ...
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Calculate the formula, and moles

If $\ce{1.84\times10^{-4}}$ moles of element A was completely reacted with element B to create $\ce{1.231\times 10^19}$ molecules of $\ce{(A3B2)_x}$ a hypothetical compound, what is the value of x? I ...
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At what temperature can molecules no longer form?

// hyper simplistic terminology in use for the question - apologies. Molecules are formed by atoms bonding together, and those bonds have an equivalent energy. At what temperature does the thermal ...
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Calculate concentrations in a system made up of molecules in order to calculate ionic strength

I understand how to calculate ionic strength where there are concentration data in molality or molarity units available and where the system is made up of only two components. However, I have been ...
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1answer
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How many molecules are there in 17.53 grams of NH4ClO4? [closed]

How many molecules are there in 17.53 grams of $\ce{NH4ClO4}$? I get to 1 mol = 118 then I get stuck.
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1answer
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Why are long oxygen chains unstable? [duplicate]

H-O-H (water), H-O-O-H (hydrogen peroxide), H-O-O-O-H, H-O-O-O-O-H, etc. This is analogous to hydrocarbon chains, methane, ethane, propane, butane, etc. Note the Hydroxygen Chains satisfy 2 covalent ...
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How would you write the empirical formula of an ion?

How would you write the empirical formula of e.g. X2Y42-?
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Calculating the Radius of a Molecule

Assuming the molecule is a sphere, would the radius of amylopectin be $9.17*10^{-22}~cm^3$? I arrived at this answer by deriving the molar volume by dividing the molar mass ($828.72~g/mol$) of ...
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1answer
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Finding molecules that you randomly create using a modeling kit

I recently bought https://snatoms.com/ (which is just a real-life modeling kit for atoms/molecules) and was just keen on learning about chemistry in general. I often randomly join atoms to make up ...
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How can the number of molecules and atoms be the same in a gas?

A sample of certain mass of gas was collected and it was found that the number of atoms and the number of molecules in the collected sample are equal. You are required to state the conclusion drawn ...
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What is the difference between ''1 C atom and 1 mole of C atoms?'' [closed]

Does 1 C atom mean 1 single C atom out of Avogadro's number of C atoms = 1 single C atom out of 6.023 X 10^23 numbers of C atoms? Does 1 mole of C atoms mean Avogadro's number of C atoms = 6.023 X 10^...
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How do noble gases bond with themselves?

Noble gases have full electron shells, which virtually blocks any other element from bonding with it. However, I've heard about cases where they bond to each other - for example, helium can ...
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1answer
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What to say 'one mole of C atoms or one mole of C molecules?

What to say 'one mole of C atoms or one mole of C molecules in CO? Please point out if I am wrong here As we know, one molecule of CO = one mole of CO molecules = 6.223 X 10^23 number of CO molecules ...
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2answers
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A mole of atoms is the number of atoms whose total weight equals the atomic weight?

My textbook says, a mole of atoms is the number of atoms whose total weight = the atomic weight. There's something in the definition that's confusing me. Now what is confusing me is: Atomic weight =...
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How is sulphur trioxide formed and why is it stable? [duplicate]

Structure of $\ce{SO3}$ (sulfur trioxide): In the molecule, if each oxygen atom shares two electrons with sulfur atom then how does the sulfur atom remain stable? It already has 6 valence electrons ...
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How to determine polarity in large molecules?

In case of small molecules like water things are more or less clear, but when I see a large complex molecule like Thyroid Hormone - how should I find out that this molecule is non-polar?
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What is the difference between “molecular mass”, “average atomic mass” and “molar mass”?

I don't understand the difference between "molecular mass" and "average atomic mass". They seem like the same thing to me. Is it that average atomic mass is just the weighted average of the "weights"/...
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Why is (1E,3Z,5E,7E,9Z,11E)-cyclotetradeca-1,3,5,7,9,11-hexaen-13-yne not antiaromatic?

The compound shown below was synthesized by Professor I M Dimm who was astonished to find that it was exceedingly stable. Prof. Dimm had expected world renown for making what he thought would be an ...
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1answer
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How does molecular collision excites the electron?

I have this question for a long time that in LASER when we do the pumping by heating how does molecular collision causes the atoms(molecules) to reach in excited state. E.g. in $\ce{He-Ne}$ laser when ...
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1answer
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Do alkali metals not form diatomic molecules?

I know hydrogen forms a diatomic molecule $\ce{H2}$, where the electronic configuration of hydrogen is $\ce{1s}$. But why doesn't lithium also form a diatomic molecule? Its electronic structure is $\...
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Molecular weight of Polymers

Addition polymerisation is defined in my textbook as the process in which a molecule or compound is formed by combination of small molecules (monomers) implicitly having greater molecular mass than ...
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What makes water a liquid (when it is)?

I'm curious about what the minimal conditions for some collection of water molecules to be liquid water are. What is the minimum number? What sort of bonds must hold? What other sorts of things I don'...
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3answers
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Why is it O-Cl-O and not O-O-Cl?

I'm currently preparing my exam and while I did never think about this question during the course, it begins to confuse me right now... Why is it the structure of $\ce {ClO_{2}-}$ like $\ce {O-Cl-O}$ ...
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Why do molecules having a higher relative molecular mass have stronger inter-molecular forces?

Why do molecules like alkanes with higher relative molecular mass ($M_\mathrm r$) have stronger intermolecular forces? For example, methane ($\ce{CH4}$) has a weaker intermolecular force than pentane (...
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Are the breaking of bonds simultaneously endothermic and exothermic? [closed]

I understand that energy is NEEDED to BREAK bonds. But don't chemical bonds already have some form of potential energy in them already? So wouldn't it make sense that even though energy is required to ...
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Can the friction of air disintegrate objects if they are accelerated enough?

Can an object be thrown so fast that the individual atoms or molecules separate in air? I mean if you could accelerate an object fast enough, would it disintegrate from the friction of air? If so, ...
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Molecular orbital theory & predicting the stability of a molecule?

A question in my general chemistry textbook gives me a list of formulas for molecules and ions. It then asks me to determine, using molecular orbital theory, whether or not each would exist in a ...
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1answer
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Stereo Isomerism - syn/anti

I was studying the types of stereo-isomerism E-Z, Cis-Trans and then I come across syn-anti stereo-isomerism this one is giving me a bit of fight in understanding, especially where lone pairs are ...
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1answer
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Why don't molecules of ionic compounds exist?

My book says: As single ions of a metal are not associated in the solid with single ions of a non metal, separate units of ionic compounds do not exist. It is, therefore, wrong to talk of a ...
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Determining the structure of N2O using hybridization

I have learnt how to determine the structure of molecules where only the central atom is hybridised like $\ce{ClF3}$, $\ce{C2H2}$, $\ce{PCl5}$, but in $\ce{N2O}$ it seems as though both nitrogen and ...
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Identification of an aromatic compound for a quiz [closed]

I need help identifying this structure for a puzzle. Original text was blurry, so a white overlay was added for readability, though some fragments might be different. Any help or suggestions are ...
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1answer
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How is the degree of unsaturation derived? [duplicate]

The formula for degrees of unsaturation is: $$1+ \frac{1}{2} \sum ( n_i (v_i-2))$$ $v_i$ = valency of atom $n_i$ = number of atoms with that valency Could someone explain how the formula works, ...
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How to find out oxidation state when compound has multiple electronegativities

How do I solve for oxidation state in something like CH3-O-F? The fluorine is more electronegative than the oxygen which is more electronegative than the carbon which is more electronegative than the ...
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1answer
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What is there in this 3D representation of organic molecules I fail to grasp?

I think there's a basic idea I'm missing about 3 Dimensional representation of molecules. I think it may be about converting to Fischer representation. Consider the following two products of ...
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What is the reason a grain of salt alters the perceived bitterness of coffee by such a high degree?

Coffee served hot can be quite bitter (presumably high pH). Several people I have known will add a single grain of salt to the coffee - which reduces the perceived bitterness. My question is: What ...