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15
votes
2answers
5k views

Why are noble metals more electronegative then most metals?

I was researching about electronegativity when I looked up what a graph of electronegativity within the periodic table is. And, this appeared. I scanned it, matching up everything I knew about the ...
7
votes
1answer
4k views

Why does lithium from the nitride whereas the other alkali metal forms the azide?

What property of lithium makes them forms the nitride, lithium nitride $\ce{Li3N}$ whereas the other group 1 elements forms the azide, like sodium azide and potassium azide - $\ce{NaN3}$ and $\ce{KN3}$...
3
votes
1answer
1k views

Does ionization energy have anything to do with how reactive an element is?

According to my textbook, fluorine has a pretty high (compared to elements like sodium) first ionization energy. But why does it have such a high requirement to ionize? After all, it actively seeks ...
19
votes
6answers
6k views

Do atoms form either a positive or a negative charge, but not both?

I do not mean at the same time, of course, but I mean it appears from an overview of the common charges formed from ionizing various elements that each element forms one or more of either positive or ...
5
votes
0answers
556 views

Difference of aggregate and cluster?

Can anyone tell me the difference of aggregates and clusters from the molecular point of view? Thank you so much.
2
votes
3answers
7k views

Determine stable oxidation state from Ionization energy

Question: Given the first, second and third ionization energies of an element (7 eV, 12.5 eV and 42.5 eV respectively), find the most stable oxidation state (or charge on the resultant ion) of that ...
1
vote
0answers
40 views

Thermodynamic-Fuel and efficiency

Why is the maximum theoretical efficiency of Ar engine higher than that of Nitrogen engine? On a molecular level. For an Otto Cycle $\mathrm{Eff} \le\left(1-r^{1-\gamma}\right)$ $\gamma=\dfrac{C_p}{...
15
votes
1answer
1k views

Why do different elements form different types of carbides?

What property of the elements make them form different types of carbides like: $\ce{Be}$ and $\ce{Al}$ - $\ce{Be2C}$ and $\ce{Al4C3}$ (Methanides) contains $\ce{C^4-}$ ion $\ce{Na}$ and $\ce{Ca}$ - $...
1
vote
1answer
1k views

What fraction of air gets expelled upon heating an empty flask?

A student forgot to add the reaction mixture to the round bottomed flask at $\pu{27 ^\circ C}$ but instead he placed the flask on the flame. After a lapse of time he realised his mistake and using a ...
4
votes
1answer
4k views

Why does hydrogen phosphate act as a base?

Let's look at question c: a) Write a balanced equation for the reaction. $$\ce{2 NaOH + H3PO4 -> Na2HPO4 + 2 H2O (l)}$$ b) When some crystals of $\ce{Na2HPO4}$ were dissolved in water, ...
3
votes
0answers
54 views

Neutralization reaction with insoluble salt (weak acid, strong base)? [duplicate]

Consider the following reaction. $\ce{2 HF(aq) + Ca(OH)2(aq) -> CaF2(s) + 2 H2O(l)}$ The reaction produced a fairly insoluble salt. Assume that this reaction proceeds entirely to completion as ...
2
votes
0answers
314 views

Coffee and orange juice concentrations with a twist

This question dates back to a time where I used to watch something called The Curiosity Show... Kinda like Bill Nye the Science Guy's show. I just can't recall the answer to this so I'm hoping that ...
1
vote
1answer
330 views

Simple procedure for showing presence of milk proteins in clarified butter (ghee)

By clarifying butter, e.g. by melting butter and filtering it, we rid ourselves of most of the protein in the butter, and are left with mostly fat. However, the separation of protein and fat is not ...
0
votes
0answers
3k views

Maximum number of double bonds a carbon atom can make

What is the maximum number of double bonds a carbon atom can make? Well, carbon has $4$ valence electrons so... it needs $4$ more to fulfill the octet rule right? If a double bond yields $4$ ...
5
votes
1answer
54k views

The Lewis structure for NCO-

I was having trouble drawing the Lewis structure for $\ce{NCO^-}$. I found this image online: But why is structure number one preferred over structure number two? Why does carbon prefer to have a ...
5
votes
1answer
6k views

How can nitrogen achieve +5 oxidation state?

Nitrogen has no available d-orbitals. Yet, it forms compounds where its oxidation state is +5, like in nitric acid. How?
-1
votes
1answer
827 views

What are the structures of potassium superoxide and xenon hexafluoride? [closed]

I have 2 questions in mind: 1) What is the structure of the superoxides? More specifically, what is the structure of $\ce{KO_2}$? 2) What is the structure of and dipole moment for $\ce{XeF_6}$?
0
votes
1answer
1k views

Using a modified Arrhenius plot to find activation energy

I have a question on how to determine activation energy from a plot using the Arrhenius equation. I am working as an assistant with general chemistry II students and their lab is the iodination of ...
2
votes
1answer
9k views

Using vapor mole fraction and pressure to determine liquid mole fraction

I am studying Chemistry by Zumdahl and Zumdahl (9th edition) and I have come across a question in Chapter 11 that I can't figure out the explanation for: Liquid A has vapor pressure x , and liquid B ...
6
votes
1answer
2k views

Why is tert-Butyl (tBu) often not listed as protecting group for alcohol?

I am not seing tBu listed as alcohol protection group in all of these places: https://en.wikipedia.org/wiki/Protecting_group#Alcohol_protecting_groups http://www.synarchive.com/protecting-group/ http:...
3
votes
1answer
586 views

Preparing an amine from an azide

Is there any mechanism available for reduction of alkyl azides to amines. One of the reactions is conversion by $\ce{Na}$ in ethanol or by $\ce{LiAlH4}$. But how do these proceed? $\ce{LiAlH4}$ will ...
21
votes
3answers
12k views

Selective nitro reduction of poly nitro compounds

Is there any way through which I could selectively reduce one $\ce{NO2}$ group from a dinitro- or trinitro- compound to an amine. I was reading Solomons and Frhyle and it says that m-dinitrobenzene ...
15
votes
1answer
4k views

What color is solid methane?

Is it blueish, perfect white or some other color? I am interested because some celestial bodies are said to be covered with methane ice.
5
votes
1answer
289 views

The partition coefficient for a chemical species across a membrane

What factors influence the partition factors across a membrane for a chemical species? Wikipedia defines the partition coefficient as: In the physical sciences, a partition-coefficient (P) or ...
1
vote
1answer
608 views

Find oxidation number of a metal in a compound

Calculate the oxidation number of $\ce{Fe}$ in $\ce{Fe2O3}$. Alright. So we have a metal and an non metal. This means that iron will lose electrons and give them to oxygen. So it will be a positive ...
3
votes
3answers
5k views

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 ...
0
votes
2answers
8k views

Why is sulfur the central atom in the Lewis structure for SO2?

So apparently the Lewis structure of $\ce{SO_2}$ is It was my understanding that the central atom is the one that is more electronegative. And an atom is more electronegative the closer it is to ...
3
votes
0answers
47 views

Does Fluoroborate gets used up in Electroplating

I've been working on Tin electroplating on the side for a while now. I've formulated a mix from my usual electroplating formula template. The mix stubbornly keeps on having the Tin ions form Tin ...
7
votes
1answer
459 views

Can molecular structure be determined without modern characterization methods?

Molecular composition can be determined in some "primitive" ways (1, 2). What about the molecular structure? Is there a way to know what's bonded to what without spectroscopy etc.? By "modern" I mean ...
7
votes
1answer
1k views

Units in modified Arrhenius equation?

The modified Arrhenius equation is used to express the rate constant in a chemical mechanism model I'm working with. The equations is as follows: $$k_\mathrm{f} = A\times T^b\times\exp\left(-\frac{E_\...
1
vote
1answer
6k views

Molar enthalpy vs Enthalpy of formation?

(Note I've refocused a previous unanswered question into a more general question. You can find the original much more specific question here) There seems to be two main ways of looking at the enthalpy ...
6
votes
1answer
1k views

Each electron shell can hold up to 2n² electrons. Is there a geometric reason for this?

It seems such a simple formula, that each electron shell can hold in principle two times a square number. I imagine there must be a geometrical reason for this, that's to do with the way electron ...
6
votes
1answer
800 views

A compound that only absorbs UV-A radiation

As a similar idea to the question A compound that absorbs all visible light, I am curious if there is a compound (or compounds) that absorb UV-A radiation (shown below)? However, preferable the ...
4
votes
1answer
3k views

Explanation of steric hindrance and existence of PI5

I have come across a following line in my textbook: $\ce{PI5}$ does not exist due to steric hindrance. I searched for the explanation of steric hindrance in Wikipedia but couldn't understand it. ...
1
vote
1answer
651 views

Is NADPH sensitive and unstable in UV light?

According to the MSDS for NADPH Tetrasodium Salt, it says to store it in a place away from heat and light. Does this include UV light or just visible light? I was told that a pure NADPH stock solution ...
-1
votes
1answer
827 views

Are concentrated salt solutions stable over time?

I have to use dilute salt solutions incredibly frequently, and it takes valuable time to make them from pure reagents every time I need them. Are concentrated salt solutions fairly stable over time? ...
6
votes
0answers
325 views

Lemieux-Johnson oxidation on cycles

Consider 5-cyano-2,2-dimethylpentyl 4-methylbenzene-1-sulfonate: What would it yield by a Lemieux-Johonson oxydation ($\ce{OsO4}$, $\ce{NaIO4}$)? My first guess would have been that $\ce{OsO4}$ was ...
7
votes
1answer
2k views

How can we balance one-half of an oxygen molecule, or any other diatomic, in a chemical reaction?

How can we balance oxygen or any other diatomic molecule with a fractional coefficient in a reaction? I mean, if we can balance oxygen atoms in an odd number what happens to other oxygen atom, and ...
1
vote
0answers
25 views

Confusion between bases (not alkali) and other -OH containing compounds [duplicate]

Since some bases are not alkaline, we can't check whether they give $\ce{OH-}$ ions or not. Ethanol also has a $\ce{-OH}$ group. Why isn't it a base?
2
votes
1answer
355 views

What is the correct nomenclature for diphenyl methane?

Can $\ce{Ph-CH2-Ph}$ be also be named as as (phenyl methyl) benzene instead of diphenyl methane? I came to this thinking that $\ce{CH2-Ph}$ can be considered as side chain at side chain.
1
vote
1answer
119 views

I need to report MoS2 values from Mo and Sulfur numbers

I'm having a hard time figuring out how to do this and yes, I have the molecular weights, just don't know how to calculate. Been 20 years since college. EDIT: I'm working with Copper ores. One ...
10
votes
2answers
1k views

Getting 3,4-dimethylhex-3-ene from but-2-ene

How can one get 3,4-dimethylhex-3-ene from but-2-ene ? $\hskip2in$ Using $\ce{Br_2}$ then two equivalents of $\ce{CH_3CH_2MgBr}$, I can get the corresponding alkane (3,4-dimethylhexane) but I don't ...
37
votes
3answers
6k views

A compound that absorbs all visible light

Is there a compound that absorbs all visible light?
15
votes
2answers
37k views

Does bleach (without rinsing) leave residues and can vinegar, baking soda neutralize them?

It's very difficult to get accurate information concerning household bleach residues. Imagine, for instance, that you pour pure (or diluted) bleach onto fabric or synthetic foam and let it dry without ...
1
vote
2answers
3k views

Calculate the molar fraction of a mixture component given only its pressure

You have a mixture of $\ce{He, Ne, Ar}$ gases with a total pressure of $8.40$ atmospheres. $\ce{He}$ has a pressure of $1.50$ and $\ce{Ne}$ has $2.00$. What is the molar fraction of $\ce{Ar}$? The ...
2
votes
1answer
974 views

Find number grams of the solute in a dissolution given its density and Molarity

Have a dissolution of $\ce{HNO_3}$ in water. The density is $1.42\ce{g/mL}$ with a concentration of $\ce{16M}$. What is the concentration in % mass/mass? Alright. So the % mass/mass is expressed ...
1
vote
1answer
77 views

What's with the 70% ethanol? [closed]

Is there a reason for all the bottles being 70% ethanol, or is it convention.
2
votes
0answers
76 views

What chemicals could be used to repair rubber tires? [closed]

I have a beaten old R/C car that I am restoring for my son. It has some nice rubber tires on it, but they are kind of old and worn. The rubber itself is almost moldy and looks matte. I could just ...
71
votes
3answers
15k views

Could a magnet pull oxygen out of the air?

I read that the $\ce{O2}$ molecule is paramagnetic, so I'm wondering: could a strong magnet pull the $\ce{O2}$ to one part of a room – enough to cause breathing problems for the organisms in the room? ...
10
votes
2answers
287 views

Discrepancies between smell and taste

In my experience, most foods smell like they taste. Fragrant soaps, however, taste quite awful in comparison to their fragrances. How can some things smell and taste identical while others are so ...

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