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1answer
2k views

Why is mass proportional to the strength of a dipole-dipole attraction? meaning more mass more strength [duplicate]

I don't understand why the mass of a molecule make it attract more to other polar molecules.
2
votes
2answers
223 views

Is N-methylimidazole an unusual solvent, or are there more common substitutes for it?

I want to test a process that was documented in the literature using N-methylimidazole. I am not doing academic research, but rather testing a documented reaction for application to an industrial ...
6
votes
1answer
89k views

Half equations for H2O2 for its reducing and oxidising nature in acidic and alkaline medium

Is there a complete list of all the half equations for $\ce{H2O2}$ - both oxidation and reduction, in acidic and alkaline conditions? I've looked on the internet but can't seem to find a list with all ...
10
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2answers
2k views

How does glue work?

Simple question. How does household glue work? How does it attach to almost any other compound? Thanks.
1
vote
2answers
360 views

How to calculate the concentration of a K₂Cr₂O₇ solution?

How many ml of acidified $\ce{K2Cr2O7}$ solution, which includes 21.6 g of dichromate ions per Litre, are required for the oxidation of 44.4 g of $\ce{CH3CH2CH(OH)CH3}$? Obviously 44.4 g of $\ce{...
-4
votes
1answer
1k views

Questions concerning redox reactions [closed]

What does it mean for an element to be reduced? What does it mean for an element to be oxidized? What is an oxidizing agent? What is a reducing agent? How do you identify oxidizing and reducing ...
1
vote
1answer
531 views

How to separate lead condensate from aluminum

A common problem in shooting sports is precipitation of lead onto aluminum suppressor baffles. (The lead presumably comes from both lead styphnate priming compound and from the base and bearing ...
4
votes
1answer
1k views

Why is dialysis tubing impermeable to sucrose?

This question was posed a couple years ago but not answered adequately. You can view the older thread here. The cellulose membrane commonly used in high school and university labs is widely available ...
20
votes
2answers
28k views

Why is a singlet state called singlet and a triplet state called triplet?

I kind of get the idea of singlet and triplet states. But why are they called singlet and triplet (what is the single and what is the triple in these cases)? I feel that I am missing something ...
4
votes
1answer
7k views

What is the appropriate procedure for determining the quantum numbers of an electron?

How do I find the set of quantum numbers for a specific electron in an element? For example, Calculate the set of quantum numbers for the 19th electron in chromium. The electronic configuration ...
1
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2answers
277 views

Addition of salt to ice

Salt is very commonly added to ice even at room temperature to prevent it from melting. Can anyone explain how does it really work?
8
votes
1answer
267 views

How strict is the “to excite electrons the energy must equal the energy state difference” fact?

We are always told that to excite an electron from one state to a higher energy states, for example from the valance band to the conduction band, the energy must equal the energy difference between ...
2
votes
1answer
628 views

Fraction of concentration of benzene in air water

We have a 120 ml water sample with an unknown concentration of benzene. If the bottle size is 160 ml (with 40 ml of air) and benzene has reached equilibrium, what fraction of benzene is left in the ...
0
votes
3answers
585 views

Configuration of a water molecule?

Water molecules are described as an oxygen atom covalently (ignoring for the monent protonization/deprotonization) bonded to two hydrogen atoms with an angle of ~104° between the hydrogen atoms (like ...
1
vote
0answers
43 views

Why does the equilibrium law work mathematically and what does it really mean [duplicate]

For example consider: $$aA + bB \rightarrow pP + nN$$ where $a, b, p$ and $n$ are moles. The equilibrium constant is $$ \frac{[P]^p [N]^n }{[A]^a [B]^b}$$ Where does this come from? I don't ...
1
vote
2answers
161 views

What is the process involved in performing a mass spectrometry experiment?

I have heard that mass spectrometry is very time consuming: why is this? What is the process involved in performing a mass spectrometry experiment? What steps are the most time consuming?
1
vote
1answer
433 views

Properties of Polyprotic acids?

I have a graph of a titration of a weak polyprotic acid with a strong base. I graphed $p\ce H$ versus amount of strong base added. Now since the acid is polyprotic, how do I determine which ...
22
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2answers
20k views

Is sodium chloride really odourless? If yes, what do I smell?

I just had to read some general descriptions of sodium chloride and it was always classified as odourless (e.g., by Wikipedia). However, large amounts of table salts (around 1 kg) have a clearly ...
4
votes
2answers
284 views

Addition of NaCl and CaCl2 to snow

In cold countries, it is a common phenomena to add salt to melt or clear snow. However, only specific salts are being commercially. So my question is that why only sodium chloride and $\ce{CaCl2}$ are ...
2
votes
2answers
2k views

Chirality of buta-1,2-diene

My teacher says buta-1,2-diene is symmetric and hence optically inactive but I think it's the opposite, because allenes with an even number of double bonds are optically active because they have no ...
0
votes
2answers
202 views

Confused with oxidation numbers

If -2 is a oxidation number and 2- is the charge, then what is - by itself, is it a oxidation number or charge? As in $\ce{Ag+}$. Also do you see $\ce{Cu + 2Ag+ -> Cu^{2+} + 2Ag}$ as a redox ...
5
votes
3answers
2k views

Easy method of analysing iodine content in supplements?

Most health-food stores carry supplements supposedly containing iodine for people with iodine deficiency. I recently bought some kelp tablets that are supposed to have iodine but as a consumer how can ...
0
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2answers
1k views

Calculus and physical chemistry [duplicate]

Is calculus and differential equations really that useful in physical chemistry? How does knowing that helps me in physical chemistry? And how much of calculus must I know in order to do physical ...
1
vote
1answer
63 views

Searching for a solvate that changes its solvation property

I'm looking for a solvate that changes its solvation property when being dried. One example of such a material is gypsum: at temperatures up to 250°C it becomes γ-anhydrite which will slowly hydrate ...
1
vote
1answer
164 views

Dissociation of ligand

If a ligand K[Ag(CN)2] is dissociated.. Which one is correct dissociation equation? $$\ce{K[Ag(CN)2] -> K+ + Ag+ + 2CN^-}$$ or $$\ce{K[Ag(CN)2] -> K+ + [Ag(CN)2]^-}$$
3
votes
2answers
3k views

Boron trihalides acidity

Boron trihalides ($\ce {BX3}$) is a Lewis acid, because it can accept an electron pair, as Gilbert N. Lewis definition. Now my question is, please arrange ($\ce {BF3}$), ($\ce {BCl3}$), ($\ce {BBr3}$),...
6
votes
2answers
179 views

How to find trace methanol content in fermented fruit/distillate?

Suppose we have some fermented (optionally also distilled) fruit/fruit juice. The sample therefore contains water, sugars, ethanol etc. Which analysis method is the simplest to find out whether the ...
2
votes
1answer
870 views

What is the difference between the reactivity of Lead subacetate and Lead II acetate undergoing a hydrothermal process?

I am attempting to adapt a hydrothermal method for synthesizing $\ce{PbS}$ nanocrystals to my school that contains a mixture of cationic and anionic surfactants sodium dodecyl sulfate (.05 mmol, SDS) ...
0
votes
0answers
52 views

Modelling planar ring molecules and their evolutions [duplicate]

This is the next step of my previous question. I am trying to simulate a circular chain (ring) of molecules which are planar (two dimensional). What I do is take a planar unknot and embed it into a ...
8
votes
1answer
9k views

Hardness and softness are terms used to describe which aspect of acidic behaviour?

What do hardness and softness mean? Is it something to do with the polarisability.
9
votes
3answers
1k views

Oxalic acid structure

What is the reason why oxalic acid has its second $\ce{-COOH}$ group flipped? I'm guessing it's something to do with steric repulsions between the $\ce{-COOH}$ groups but I'm not sure.
0
votes
1answer
775 views

Heat of combustion per mole and per kilogram

I need to calculate the heat of combustion per mole and per kilogram of complete combustion of, say, X. I write reaction : $\ce{X + O2 -> ... + Q}$ Find Q using Hess law Now, what do I do after ...
3
votes
2answers
6k views

Stability of transition metals in aqueous solution

Which is more stable in aqueous solution: $\ce{Cr^3+}$ or $\ce{Mn^3+}$? Why? My approach: $\ce{Cr^{3+}}$ should be more stable as the $\ce{3d}$ electrons will enter the $\mathrm{t_{2g}}$ orbitals. ...
0
votes
1answer
66 views

Modelling planar molecules and their evolutions

I am trying to simulate a chain of molecules which are planar. Can anyone please give me an example of the molecular chain which can stay as planar with it's minimum energy state is planar. A ...
0
votes
1answer
2k views

Does Nitrogen dioxide change colour if we put it in a constant temperature of e.g. 100 kelvin?

The changing of the colour of $\ce{NO2}$ is because of a change in temperature, resp. heating and cooling?
2
votes
2answers
149 views

How do i detect the compounds a plant is made of, automatically?

Let's say I want to take a random plant , and get the chemical formulas of the compounds he's made of. Is there an automated method for doing so and how costly is it(roughly) ?
7
votes
3answers
22k views

How to determine the pH of a mixture of two weak acids?

We’ve two solutions: Solution 1 $\ce{HCOOH}$ its concentration is $c_1=10^{-2}\ \mathrm{mol/l}$ and its volume is $V_1 = 50\ \mathrm{ml}$ and its $\mathrm{pH}_1 = 2.9$. Solution 2 $\ce{CH_3COOH}$ ...
2
votes
1answer
99 views

How do I lookup a polymer by its structure?

This is more of a meta-chemistry question, but, here goes... Given the structure of a polymer, how can I search online for which polymer it is? Specifically, I have an image like this: I'd also ...
7
votes
5answers
42k views

Why is weight of 1 mole of substance equal to atomic/molecular mass in grams?

Why is weight of 1 mole of substance equal to atomic/molecular mass in grams? According to me, it happens because mole has been defined in such a way. It is defined as the numbers of particles in $\...
-8
votes
1answer
908 views

Find the molecular formulas of these alkanas and alkenes [closed]

Can Somebody please solve this chemistry question It came as a part of a previous test and i wasn't able to find a way to use ny/nx since all my answers would be negative. It wasn't a homework problem....
0
votes
1answer
586 views

What is the compression work? [closed]

A cylinder contains 2 kg of steam at 200 kPa and 200 $^\circ$C. Now steam is compressed at constant pressure until its temperature rises to 250 $^\circ$C. What is the work done during this compression ...
0
votes
1answer
127 views

Boilng vodka for A/C cleaning

I hope this doesn't sound too strange. I have plenty of cheap vodka and want to clean the A/C on my car. So I thought about boiling 1/2 litre of vodka in my car while I ran the A/C with ...
6
votes
1answer
2k views

Why is Cyclodextrin cavity hydrophobic?

Actually this is going to be a list of interconnected questions. Please bear with me. Wikipedia article on cyclodextrin (CD) says that it is hydrophobic from inside. (1) How is it hydrophobic when ...
0
votes
1answer
302 views

Octahedral Voids

The total number of octahedral void(s) per atom present in a cubic closed pack structure is (a) 1 (b) 2 (c) 3 (d) 4 PS- I answered it (d) 4 but a key on internet says it is (a) 1. Please clarify ...
4
votes
2answers
9k views

Cathode + Anode + Rechargeable battery

I'm confused by the following from this webpage: The cathode is a metal oxide and the anode consists of porous carbon. During discharge, the ions flow from the anode to the cathode through the ...
11
votes
2answers
24k views

Why NH4OH? Why not NH3(aq)?

The title says it all. I had this question when helping someone with their high-school chemistry homework. What are the reasons that someone would use an (from my point of view) obfuscated notation?
0
votes
1answer
1k views

Titration color change duration [closed]

Why is it that in titration a color change occurs initially but then the solution quickly reverts to its previous color? Thanks so much!
2
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2answers
1k views

Which one really determines how people feel. Heat or temperature? [closed]

We use water to cool down some machines because water has high heat capacity, which means it takes more energy to increase 1 degree. Heat transfer occurs only when temperature is different. We cool ...
5
votes
2answers
123 views

Maximum Pressure of Covalently Bonded Material

At high enough pressure, atomic material no longer exists, for example under the conditions of a neutron star. Is there a different maximal pressure above which covalent bonds no longer exist?
0
votes
2answers
1k views

Determine products of NH4NO3 hydrolysis [closed]

What are the products of the following hydrolysis reaction? How do you know? $$\ce{NH4NO3 + H2O <=> ?}$$

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