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Is there a method in chemistry to alter the energy of atomic bonds by forcing atoms closer together in a smaller volume? Similar to how pressure squeezes atoms closer together.
The official solution is that A has branched / side chains, weak Van der Waals forces between the polymer chains, less compact packing than B, and large inter-chain distances. B has no branched chains, hydrogen bonds between the polymer chains, compact packing, and small inter-chain distances. 1. What does a branc...
“Branched chain” simply means that the main carbon backbone has other, smaller carbon backbones coming off of it. You’re correct, a hydrogen atom would have to be removed from a carbon atom in order to attach another polymer chain. Generally, branched chains decrease the density of a polymer because they fill space les...
I would like to test samples of polyethylene glycol 3350 ($\ce{H−(O−CH2−CH2)_n−OH}$ with an average molecular weight of 3350, so n is around 75) to determine if there are any impurities and if so the rough concentration of them. Some likely impurities that may be present are: - ethylene oxide - diethylene glycol ...
I have noticed that, when a structure with bars (such as a gate or a grate) develops rust, this sometimes happens differently across the bars. In particular, it seems that the bars are alternatively clean and covered in rust. The photos below (taken by me) illustrate this effect (I have highlighted the rusted bars w...
Hello dear I have a small question I want to do kjeldahl distillation for a 100 mL sample of water after reduction with devarda's alloy to measure the concentration of nitrate nitrogen... I want to know what is the quantity of alloy must be added to 100 mL water?
I recently learned about the MO bonding model in metals, where many metal atoms form lots of orbitals close in energy that form bands. However, I can't understand the bonding in d10 metals. It seems to me that if they form MOs, then the bonding and antibonding orbitals will both be filled, resulting in net zero bonding...
>What is the total number of stereoisomers for the compound $2,3,5,6$-tetrachloroheptane? [![enter image description here][1]][1] [1]: https://i.stack.imgur.com/1xGY1.png I figured the answer to be $16$, but the answer given is $10$. [Here is a similar question](https://chemistry.stackexchange.com/q/107033/...
>What is the total number of stereoisomers for the compound 2,3,5,6-tetrachloroheptane? > > [![2,3,5,6-tetrachloroheptane][1]][1] [1]: https://i.stack.imgur.com/1xGY1.png I figured the answer to be 16, but the answer given is 10. [Here is a similar question](https://chemistry.stackexchange.com/q/107033/7951...
I understand that there four rules for aromaticity: 1. cyclic 2. conjugated double bonding (every atom in the ring should be sp2) 3. huckle number should be 2, 6, 10, 14, 18, ..18 4. planar ring The 2nd question should be 4 electrons and is antiaromatic, but how about the first question? [![enter image descrip...
I have a case to contradict my own question but in few books, it is given that x/y is always intensive. So I got confused. My case is as follows : Let a wire be our system whose resistance is R, area of cross section is A, length is L and constant of resistance be ρ. V,R are extensive V(volume) = A*L ...
If x and y are 2 extensive properties of a system then is x/y always intensive?
My reference book (Princeton Review for SAT Chemistry Subject Test) mentions that: > Proteins and carbohydrates are both polymers; however, only > carbohydrates commonly form branched polymers. Glycogen and cellulose > are both carbohydrate polymers made up of glucose monomers; glycogen > is a highly branched pol...
I'm new here and I'm still learning, I understand that there four rules for aromaticity: 1. cyclic 2. conjugated double bonding (every atom in the ring should be sp2) 3. huckle number should be 2, 6, 10, 14, 18, ..18 4. planar ring The 2nd question should be 4 electrons and is antiaromatic, but how about the f...
I have a case to contradict my own question but in few books, it is given that x/y is always intensive. So I got confused. My case is as follows : Let a wire be our system whose resistance is R, area of cross section is A, length is L and constant of resistance be ρ. V,R are extensive V(volu...
If I had two teaspoons of pink strawberry gatorade and one teaspoon of a clear thick liquid and when mixed together it turned bluish purple in a chemical reaction, what might the thick clear liquid be?
Let us take a system with initial state (1) and a final state (2).Now let us change the state of the system from 1 to 2: - Case 1) Reversibly by adding heat Qrev.So now the entropy change ∆S=Qrev/T.Also the enthalpy change ∆H=Qrev.So the Gibbs free energy change is 0(plug in the vari...
Why is Gibbs free energy different for different processes?
Under constant pressure and temperature ∆G=∆H-T∆S. Let us take a system with initial state (1) and a final state (2).Now let us change the state of the system from 1 to 2: - Case 1) Reversibly by adding heat Qrev.So now the entropy change ∆S=Qrev/T.Also the enthalpy change ∆H=Qrev.So the Gibbs f...
Manganese has an oxidation state of +7 in potassium chromate. When reacted with sulphuric acid, how does it tend to have +2 oxidation state by forming MnSO4 along other in the products. In acid, there is already tendency to donate proton and not electrons. Yet it forms +2. While in basic medium Manganese forms +7 to +6...
KMno4 is the strongest oxidizing agent. So why does it tend do have +2 oxidation state with reaction with acids?
Manganese has an oxidation state of +7 in potassium permanganate. When reacted with sulphuric acid, how does it tend to have +2 oxidation state by forming $\ce{MnSO4}$ along other products ? In acid, there is already tendency to donate proton and not electrons. Yet it forms +2. While in basic medium Manganese forms ...
Does water from glaciers have many minerals (hard water) or would it be considered pure or distilled water?
What are the properties of water in glaciers?
I was told that I can use an Ozone generator to get rid of fungus (resulting from not enough fresh air I suppose). But I didn't find any reputable source for that claim. Would it work, Chemists of Stackexchange? What should we pay extra attention to?
Use an Ozone generator to get rid of fungus in the flat?
I'm still learning huckel rule and aromaticity in different compound. For the 1-methoxy-1,3,5,7-octatetraene, is it correct that it has 8 electrons inside the cycle, but since they will be 8, then it is antiaromatic? And for the Imidazole, is it 6 electron inside because the N: doesn't contribute to the pi, or is i...
This is a problem of counting lone electron pairs as part of the delocalized pi system. In pyrrole you count the lone pair on the nitrogen, in pyridine you don't. What's the difference? In pyrrole you have the lone pair left over after you have given every ring a ligand (the outer hydrogen atoms). With the sigma ...
Here is a [good commentary](https://www.noai.org/mold-remediation-ozone-generator), in my assessment, on which I will review the chemistry latter, to quote: >A debate has swirled about for years about the use of ozone generators for mold infestations. Some mold experts call ozone "useless" for mold treatment, while...
Here is a [good commentary](https://www.noai.org/mold-remediation-ozone-generator), in my assessment, on which I will review the chemistry latter, to quote: >A debate has swirled about for years about the use of ozone generators for mold infestations. Some mold experts call ozone "useless" for mold treatment, while...
Here is a [good commentary](https://www.noai.org/mold-remediation-ozone-generator), in my assessment from the National Ozone Association, on which I will review the chemistry latter, to quote: >A debate has swirled about for years about the use of ozone generators for mold infestations. Some mold experts call ozone...
Here is a [good commentary](https://www.noai.org/mold-remediation-ozone-generator), in my assessment from the National Ozone Association, on which I will review the chemistry latter, to quote: >A debate has swirled about for years about the use of ozone generators for mold infestations. Some mold experts call ozone...
Here is a [good commentary](https://www.noai.org/mold-remediation-ozone-generator), in my assessment from the National Ozone Association, on which I will review the chemistry latter, to quote: >A debate has swirled about for years about the use of ozone generators for mold infestations. Some mold experts call ozone...
Some websites, such as [this textbook](https://chem.libretexts.org/Courses/Pacific_Union_College/Quantum_Chemistry/12%3A_Group_Theory_-_The_Exploitation_of_Symmetry/12.02%3A_Symmetry_Elements#.5C(S_n.5C):_an_.5C(n.5C)-fold_axis_of_improper_rotation_Symmetry), mention how generally a plane of symmetry or inversion cente...
Example of a chiral molecule with a plane of symmetry and/or inversion center?
What is the Mechanism for the Hydrogenolysis of Benzyl Ethers?
What is the mechanism of benzyl ether hydrogenolysis?
Example of a chiral molecule without a plane of symmetry or inversion center?
The theory behind this has been addressed before, but I can't find any actual *examples* of such compounds on SE, so I'll write a short answer. ---- > Are there any molecules lacking plane of symmetry/center of inversion but that are achiral due to presence of an axis of improper rotation? Yes, although such e...
Some websites, such as [this textbook](https://chem.libretexts.org/Courses/Pacific_Union_College/Quantum_Chemistry/12%3A_Group_Theory_-_The_Exploitation_of_Symmetry/12.02%3A_Symmetry_Elements#.5C(S_n.5C):_an_.5C(n.5C)-fold_axis_of_improper_rotation_Symmetry), mention how generally a plane of symmetry or inversion cente...
Example of an achiral molecule without a plane of symmetry or inversion center?
I understand the bulk of MO theory , the formation of the bonding and anti bonding MOs etc. However, the topic about s-p mixing is quite puzzling to me. As a general rule of the thumb, I was taught that diatomic molecules up to N2 would exhibit s-p mixing, while the molecules past that threshold, O2 and above, would ha...
My understanding is that the water in glaciers constitutes over 2/3 of the designated 'freshwater' on earth and is an integral part of the so-called water-cycle. Per [U.S. Geological Survey](https://www.usgs.gov/special-topic/water-science-school/science/ice-snow-and-glaciers-and-water-cycle?qt-science_center_object...
[![enter image description here][1]][1] [1]: https://i.stack.imgur.com/uq2G4.png I think that the above are identical compounds as (I) doesn't exist in the shown form but it would exist naturally in the (II) form, so these should be identical. But these are mentioned to be geometrical isomers in a book that I...
Are these identical?
> [![Cyclodecapentaene][1]][1] [1]: https://i.stack.imgur.com/uq2G4.png I think that the above structures are identical compounds as **I** doesn't exist in the shown form but it would exist naturally in the **II** form, so these should be identical. But these are mentioned to be geometrical isomers in a bo...
Are these molecular structures of cyclodecapentaene identical?
A is beaker with 0.1M 25cm3 solution of NH3. B is beaker with 0.1M 5cm3 HCl. Now the solution of A and B is mixed. What will be the end Ph of the mixture? Kb = 3.3 × 10^-5 I believe the mixture will become a buffer solution and we should use Henderson equation to solve this. I would really appreciate some opinion on...
Assuming that gases are ideal simplifies expressions for the change in internal energy and enthalpy. For ideal gases at constant temperature and composition ($\Delta T=0$ and $\Delta n=0$): $$\Delta U = 0\\\Delta H = 0 \tag{1}$$ These expressions are *not* general. They apply to **ideal gases at constant tempera...
I have learnt that temperature sort of indicates the internal energy of a system, or at least this is my intuition. So if temperature is constant, then internal energy is constant as well. But in the derivation of the following formula $$\begin{align}{ {\Delta H = \Delta U + \Delta n_g RT}} \end{align} $$ T does...
I am interested in nitrating an aromatic ester in a solution of dichloromethane. I found the following paper that describes creating a nitric acid solution in dichloromethane using KNO<sub>3</sub> and sulfuric acid: >Strazzolini P, et al. "Nitric Acid in Dichloromethane Solution. Facile Preparation from Potassium Ni...
> **A** is beaker with $\pu{0.1 M}$ $\pu{25 cm^3}$ solution of $\ce{NH3}.$ **B** is beaker with $\pu{0.1 M}$ $\pu{5 cm^3}$ $\ce{HCl}.$ Now the solution of **A** and **B** is mixed. What will be the final $\mathrm{pH}$ of the mixture? $K_\mathrm{b} = \pu{3.3E-5}.$ I believe the mixture will become a buffer solution a...
First of all: Reduction is just a fancy way of saying "gain of electrons". The posed question can thus be reformulated as: **What happens to water, if it gains more electrons?** In order to answer this, we should have a look at the oxidation numbers of water: Since oxygen is more electronegative, it has an oxi...
What happens when FeF3 is reacted with benzene?
My teacher started a chapter called "Carbon and its compounds", Which is just an intro to organic chemistry . In which she taught about fullerenes structure and examples and also told that fullerenes have even number of carbon atoms. I got curious and asked why but she didn't answer me. So I went and googled it but sti...
Why do Fullerenes have even number of carbon atoms?
Phenyl carbonation is said to be unstable because the + charge on it cannot be stabilized by Resonance or any other electronic effects, so my question is that if the resonance occurs in the direction shown in the below picture the + charge can be delocalized to some extent, so will it adapt that ? [![Phenyl Carboc...
Why Phenyl Carbocation is unstable?
We know that temperature is proportional to the average kinetic energy of a system. We also know that temperature is not the same as energy because the temperature is intensive while the temperature is extensive. This lead me to think that temperature was some sort of energy density, like how density represents the "av...
What is the fundamental difference between temperature and energy?
In thermodynamics, the basis for a definition of temperature is provided by the [$0^{\text{th}}$ Law][1]: two bodies independently in thermal equilibrium with a third body are in thermal equilibrium with one another. Thermal equilibrium allows the definition of temperature: two bodies in thermal equilibrium are said to...
I am working on an art project that will involve storing filings of various metals (e.g., iron, copper, zinc) in a colorless fluid. I want to prevent the metals from oxidizing for several years, so water is out. I already have 70% isopropyl alcohol. Will this work, or will the remaining 30% water be a problem? If not, ...
What fluid can I store metal filings in so they do not oxidize?
Some websites, such as [this textbook](https://chem.libretexts.org/Courses/Pacific_Union_College/Quantum_Chemistry/12%3A_Group_Theory_-_The_Exploitation_of_Symmetry/12.02%3A_Symmetry_Elements#.5C(S_n.5C):_an_.5C(n.5C)-fold_axis_of_improper_rotation_Symmetry), mention how generally a plane of symmetry or inversion cente...
I know that during the development process the developing agents reduce exposed Ag ions to silver. But what happens to Metol which is one of the developing agents?
What happens to metol during the paper development process in black and white photography? Can it be described in equation?
> An unknown sample was analysed using infrared spectroscopy. What is > the compound? [![enter image description here][1]][1] [![enter image description here][2]][2] [1]: https://i.stack.imgur.com/ao3q6.png [2]: https://i.stack.imgur.com/F5Eml.png So I am having difficulty in using the infrare...
How to determine the unknown molecule using the infrared spectroscopy?
Please help me clarify the title if you come up with a better way to put it (you certainly will). My question is the following: If you make a mix of equal parts of various acids (Bicarbonate, Hydrochloric, Nitric, Sulfuric, etc.) and throw some metal in there that will ionize and wait for a while until you have...
Can the electrochemical stability of a aqueous KOH solution be increased by adding more KOH?
Why is *perchloric* acid called so? I am aware of the rules, but why is it not called *hyperchloric* acid? Or is it correct to also refer to *perchloric* acid as *hyperchloric* acid?
> An unknown sample was analysed using infrared spectroscopy. What is > the compound? [![enter image description here][1]][1] [![enter image description here][2]][2] So I am having difficulty in using the infrared data to determine the unknown compound. I keep on misinterpreting the information on the Inf...
Please help me clarify the title if you come up with a better way to put it (you certainly will). My question is the following: If you make a mix of equal parts of various acids (Bicarbonate, Hydrochloric, Nitric, Sulfuric, etc.) and throw some metal in there that will ionize and wait for a while until you have...
Is there a tendency that could be used to generally forecast how a double salt might dissolve in aqueous medium compared to the simple salts of its constituents? Example: There is metal A, metal B and acid C. The solubility of AC and BC are known. Could one use these as a rule of thumb to know what to expect...
Counting # of atoms don't match in rounding? The total number of atoms contain in 1.0L as 1000g of liquid water must equal the total number of atoms contained in a gas released by 1000g of liquid water. A mole of water molecules contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms. Avogadro's number is 6....
Please help me clarify the title if you come up with a better way to put it (you certainly will). My question is the following: If you make a mix of equal parts of various acids (Bicarbonate, Hydrochloric, Nitric, Sulfuric, etc.) and throw some metal in there that will ionize and wait for a while until you have...
This is only a comment on the answer by Pallas, which I upvoted: [![enter image description here][1]][1] [1]: https://i.stack.imgur.com/EGfh1.jpg Fig. 3-4. The wave function and probability distribution as functions of r for the n = 1 level of the H atom. The functions and the radius r are in atomic units ...
Counting # of atoms don't match in rounding? The total number of atoms contain in 1.0L as 1000g of liquid water must equal the total number of atoms contained in a gas released by 1000g of liquid water. A mole of water molecules contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms. Avogadro's number is 6....
So the easiest non-chemical answer is to search for fence corrosion in [google][1] As you will see a quick glance is showing that you probably have taken a non significant sample in your investigation since there is plenty of fences where you have a uniform corrosion. Indeed there can be also more chemical explana...
The theory behind this has been addressed before, but I can't find any actual *examples* of such compounds on SE, so I'll write a short answer. ---- > Are there any molecules lacking plane of symmetry/center of inversion but that are achiral due to presence of an axis of improper rotation? Yes, although such e...
How does Metol (4-(methylamino)phenol sulfate) react when developing black and white photos?
My textbook introduced PBr3 by stating that it leads to an inversion in stereochemistry since it always goes through an SN2 pathway, unlike using HBr. My question is that since Br- is a reasonably good nucleophile, so I assume it would most likely proceed through SN2 in a substrate with a secondary carbon anyway. Bo...
I saw that most neutralization reactions produce water while some do not. How can I know if water will be a product in a given neutralization reaction? I initially thought that water is a product only when an acid reacts with an alkali (producing hydroxide ions) but there apparently exist some counterexamples lik...
I was recently assigned a lab where I was to observe several properties of the chemicals Acetone and Glycerol then use my observations to predict their overall Intermolecular Force strength. The properties I observed were: Surface Tension: Here, I found that Acetone had a much higher surface tension than Glycerol...
Can we predict the IMF strength of Acetone vs Glycerol?
https://en.wikipedia.org/wiki/Weighing_scale Is it possible to view and capture real time values of Electronic balance measuring instrument using wired, wireless technology on television set or computer monitor? Scenario Chemistry labs - Electronic balance interfaced wired/wireless with the television set or c...
https://en.wikipedia.org/wiki/Weighing_scale Is it possible to view and capture real time values of Electronic balance measuring instrument using wired, wireless technology on television set or computer monitor larger screens? Scenario Chemistry labs - Electronic balance interfaced wired/wireless with the tele...
I am dealing with some basic reactions in organic chemistry. One of these is the acid reflux of alcohols. Something I came across was hydride shifts. I know how and why they occur, but I don't understand why they are called 1,2 hydride or methyl shifts. What do these numbers indicate? I initially thought it would be th...
https://en.wikipedia.org/wiki/Weighing_scale Is it possible to view and capture real time values of Electronic balance measuring instrument using wired, wireless,CCTV technology on television set or computer monitor larger screens? Scenario Chemistry labs - Electronic balance interfaced wired/wireless with the...
How to read character table?
I was trying to understand why AgCl does not dissolve in HNO3 and the reaction I could think of was something like this: AgCl+HNO3---->AgNO3+ HCl I could not understand why this reaction wouldn't take place. Research on similar reactions further led me to the question: can a weak acid react to give a stronger aci...
Can a weak acid react to give a stronger acid?
I was trying to understand why $\ce{AgCl}$ does not dissolve in $\ce{HNO3}$ and the reaction I could think of was something like this: $$\ce{AgCl + HNO3->AgNO3 + HCl}$$ I could not understand why this reaction wouldn't take place. Research on similar reactions further led me to the question: "Can a weak acid reac...
Can a weak acid react to give a stronger acid? Well, yes, if you set up the right conditions. For instance, sulfuric acid (estimated first pK = -3) can be heated with $NaCl$ to boil off $HCl$ (pK = -5.9) according to Wikipedia. $HCl$ is driven from the reaction arena as a gas. You will claim that’s a special case, w...
"The quantity of reactant remaining after $n$ half lives is: $$A_n=\frac{A_0}{2^n}$$ where, $A_0=$ initial concentration and $A_n=$ concentration after n half lives." My text book(not an international standard) refers this statement to be true for First order reaction only. My confusion: Shouldn't this state...
Is the given statement valid for all order of reaction in Chemical Kinetics?
I don't understand how the bond dissociation energy **increase** as the polarity/ electronegativity difference of a diatomic molecule **increases**? This relates to how Pauling determined the values for electronegativity for all the elements and how delta (if big) shows that the molecule is polar. Delta being: $\...
I'm wondering if (1) it is at all possible to vacuum distill citric acid without the slightest decomposition, (2) If it's something that can easily be done in a small lab with widely available equipment? I've looked on internet and found the following data: ~154C Melting Point (Anhydrous Citric Acid) ~175C ...
Is it possible to vacuum distill citric acid?
It's been a while since I've dealt with these, but do character tables include all possible symmetry operations? I am looking at the $D_\mathrm{\infty h}$ point group table and it lists $C_\infty$, $\sigma_\mathrm{v}$, $S_\infty$, $i$, and $C_2$. But doesn't it also have a $\sigma_\mathrm{h}$? Why is this not inclu...