All Questions

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0answers
3 views

Thermal stability of barium peroxide and barium oxide

why is barium peroxide more thermally unstable than barium monoxide Do I answer it based on the bonding and structure?
0
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0answers
12 views

Properties of semi metal

My textbook writes a lot about metal and non-metal but only two sentences about semi-metal. This is what textbook: Semi-metal are also called metalloid, have the properties of metal and non-metal. ...
1
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1answer
25 views

Why do double bonds break

So today we performed an experiment, where we mixed cyclohexene with Bromine water. The equation was which seems to make sense. The Bromine water we were using was decoloured as evidence that this ...
1
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0answers
8 views

How do zeolites work in a cat cracker?

Been learning about catalytic cracking of long chain hydrocarbons into shorter chain hydrocarbons, in which the catalyst zeolite is used so that the temperatures needed for the cracking are much lower ...
-1
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0answers
8 views

Phase Diagram of Polymorphs vs. Binding Energy. [on hold]

Phase diagrams show how various polymorphs are favored at specific temperatures and pressures. I am interested in a 3-axis diagram showing the binding energy on the third axis. Ideally there would ...
1
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2answers
17 views

Fire resistance of PVC

In a paper that I'm reading, it states that The presence of Chlorine atoms in polyvinyl chloride make it flame resistant and I'm just wondering why the presence of Cl will make it flame ...
1
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1answer
17 views

A way to calculate orbital energy of an electron

Maybe this is just not included in my course, but I still wonder how to calculate the binding energy of an electron at a certain electron orbital. Intuitively,The ionization energy of an element ...
0
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1answer
8 views

Exothermic reactions at high temperature and the chemical equilibrium

Why are many exothermic reactions, like Haber process, conducted at high temperature, thus their unfavourable equilibrium position?
0
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1answer
21 views

If $ds>=dq/T$ for a spontaneous change is $ds<=dq/T$ for a non-spontaneous change and is that even possible?

I am struggling with the concept of entropy but might be on the verge of understanding it. The Clausius inequality - $ds>=dq/T$ - is true for all spontaneous changes with the equality for ...
1
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1answer
24 views

How is ethanenitrile protonated?

I know that the proton will attack the HOMO, but I'm having difficulty imagining how this will happen. Thank you.
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0answers
13 views

Find the final temperature and the amount of ice left in the system [on hold]

 10 g of ice at -10°C is added to 10 g of water at 85°C. What is the final temperature and amount of ice left in the system? (System is kept inside an ideal insulator). a) 0°C, 0 g b) 0°C, 2 g c) ...
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0answers
8 views

Q-value for fission [on hold]

if the Q-value for fission of Bi-209 is approximately 160 Mev,estimate the critical energy for fission of this nucleus?
1
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1answer
17 views

Is Benzene Carbaldehyde a correct name?

.. For Benzaldehyde? I'm (always) getting confused between common and IUPAC names. If the above name is correct then is it common one or IUPAC, and why don't we use it more often? Any help would be ...
2
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1answer
37 views

stone which turns to black on exposing to atmosphere?

My mom is using a stone like substance as a dye for hair recommended by a herbalist. That stone becomes black when exposed to air. Do you know which compound is this?
0
votes
1answer
16 views

How is the octane percentage defined?

Normally octane percentage is mentioned on petrol (95% octane). How is this defined? Is it percentage of chemical or some other parameters?
5
votes
1answer
287 views

Why do many pharmaceuticals contain fluorine?

What exactly does fluorination of some compound do in a biological sense? I read the following things about what fluorine does for drugs: Fluorine withdraws electron density and can make an acid ...
1
vote
1answer
23 views

Electrolysis on aqeuous solution

I know when electrolysis on a concentration aqeuous solution which contains halide ions($Cl^-$ , $Br^-$ , $I^-$). The halide ions is discharged although $OH^-$ is more easily to discharged. For ...
2
votes
1answer
19 views

Why are square planar coordination compounds with four different ligands optically inactive?

Why square planar co- ordination compounds of type Mabcd do not show optical activity, although they contain 4 different ligands ( i.e. chiral central metal atom)
0
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1answer
8 views

How can we measure electronic excitation in some “nm”(nanometres)?

I have no idea to which concept this belongs: The widest range over which electronic excitations in organic compounds occur, is A) 200 nm – 780 nm B) 220 nm– 500nm C) 250 nm– 700 ...
0
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1answer
22 views

Which vibrational modes of CO2 and CSO do not lead to IR absorption bands?

I recently came across this question, I have no idea about IR: Which of the following vibrational modes show no IR absorption bands? A) Symmetric CO2 stretch B) Antisymmetric CO2 ...
0
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1answer
19 views

Chemical composition of petrol

What is the chemical composition of petrol? What are the molecular available in petrol? Some time which is marked with 95% octane. So what is the remain element occupied 5%?
0
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1answer
10 views

Fermentation in the presence of UV light

Does the presence of UV light, or any radiation for that matter, affect the process of fermentation? I'm not sure, but I seem to recall somebody telling me before that yeast will not function ...
0
votes
1answer
9 views

Trouble to predict the effect of pressure and temperature for a reaction in equilibrium

I have trouble to predict the effect of decreasing pressure and increasing temperature on the reaction $N_2 +O_2 = NO_2$. Increasing temperature caused this reaction to shift in the forward direction ...
2
votes
1answer
20 views

Why can't the conjugate base of benzoic acid be stabilized by conjugation with the aromatic ring?

All the carbon and oxygen atoms are sp2 hybridised and can have a p orbital in the correct plane yet only conjugation of the COO- group occurs. I can't think why. I can't draw resonance structures for ...
1
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1answer
23 views

Compressible Factor

I 've a soft question on the terminology of compressibility factor. It is termed compressible factor because, its value determines how any reals gas is compressible with respect to an ideal gas ...
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0answers
11 views

Electrochemical Equilibrium with molar mass [on hold]

The electrochemical cell described by the cell notation has an $\mathrm{E^o\ of\ 0.10 V}$. Calculate the maximum electrical work (kJ) the cell has done if $\mathrm{157.41 g}$ of $\ce{H+(aq)}$ (Molar ...
4
votes
2answers
145 views

How can double compounds like XeO4 form tetrahedral structures despite having double bonds?

Xenon tetroxide is tetrahedral despite having double bonds. Is it something to do with d orbitals? Also things like sulfur trioxide (trigonal planar with three double bonds but the sulfur is ...
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0answers
19 views

Why are only ozonides of heavier elements stable?

Most ozonides which are stable are of Cs, Rb, K but not of Na, Li. Why? Why they have no mention often?
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0answers
15 views

Cation exchange capacity via IR spectroscopy? Is it as good as barium exchange? What is the intutition on how it works?

Cation exchange capacity is often regarded as the single best summary statistic for soil fertility. Years ago, I learned how to measure it myself, in a soil lab. I used compulsive barium exchange, ...
1
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3answers
38 views

Plotting p/T against T

This is about the ideal gas equation $$pV=nRT$$ to plot ${p}\over{T}$ against $T$, where ${nR}\over{V}$ is constant. How would this graph look like?
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2answers
49 views

Doubt in Cannizzaro reaction

My doubt is, how do we predict the products of a cross Cannizzaro disproportionation in presence of a concentrated base? Ie, How to judge which of the aldehydes (both don't have any alpha hydrogen) is ...
0
votes
0answers
12 views

Analytical chemistry - solid phase extraction [on hold]

how to use solid - phase extraction of Zn(II) , Cu(II) , Pb(II), Co(II) employing L2 chemically attached to sol-gel ( L2 : N',N'2-bis[ (1E)-1-(2-pyridy1)ethylidene] ethanedihydrozide
0
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0answers
6 views

use solid-phase extraction of Zn(II) ,Cu(II) , Pb(II),Co(II) employing N',N'2-bis[ (1E)-1-(2-pyridy1)ethylidene] ethanedihydrozide to sol-gel [on hold]

use solid-phase extraction of Zn(II) ,Cu(II) , Pb(II),Co(II) employing N',N'2-bis[ (1E)-1-(2-pyridy1)ethylidene] ethanedihydrozide to sol-gel
0
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0answers
28 views

Flakes rather than cubes [on hold]

In the supermarket, I walked to the seafood section. Then, I discover the ice surround is not in cubes, it's in flakes form, meaning thin piece of water. So,my question how do these water flakes ...
1
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1answer
22 views

What is the difference between carboxylate ions and groups?

I would like to know the difference between carboxylate ions carboxyl groups? An example is is $\ce{COOH}$ and $\ce{COO}$.
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1answer
29 views

Oxygen dissolve in water

I know that $CO_2$ and $O_2$ are slightly soluble in water ($H_2O$) In my understanding, when carbon dioxide dissolve in water, they will react to form carbonic acid just like the equation below. ...
3
votes
2answers
26 views

The pH of a neutralized solution

If pH is defined as the concentration of Hydrogen ions in solution, then how can a 'neutralized' solution (defined as having an equal amount of Hydrogen and Hydroxide ions) have a pH other than 7? ...
1
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2answers
23 views

Reactivity series of metal

I have learned about metal and their reactivity series. However, why metals have different reactivity? What are the factors of different reactivity rate for metal? All I can think of is the number of ...
0
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0answers
12 views

determine temperature increased? [on hold]

On heating a gas it pressure and volume both increases.By lowering temperature one fourth of initial number of moles of air are taken in to maintain the double pressure and volume. By what fraction ...
1
vote
3answers
32 views

Strong and weak acid

I know sulphuric acid is a strong acid and acetic acid is a weak acid. However when I write them in their chemical symbol. Sulphuric acid: $\ce{H2SO4}$ Acetic acid: $\ce{CH3COOH}$ And I realise ...
4
votes
2answers
63 views

How ‘lively’ would this ‘health’ potion be?

I’ve stumbled across a rather peculiar recipe for a allegedly ‘health’ potion in a computer game, composed of an unspecified amount of each of the following: rust (iron oxide) saltpetre (potassium ...
0
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1answer
25 views

I need help with finding out how to get 2g of Lead (II) Iodide? [on hold]

I need to get 2 grams of lead (II) iodide precipitate but I don't know how much lead (II) nitrate and potassium iodide I need to get that result. The balanced chemical equation is: $$\ce{Pb(NO3)2 + ...
0
votes
0answers
17 views

Find the amount of moles [on hold]

How can I calculate the amount of moles of water that is formed given a theoretical value of -55.90 kJ/mol $\ce{H2O}$ that is formed and from using the amount of joules of heat that is liberated.
2
votes
0answers
22 views

What are the specific disadvantages of using a bio-catalyst (called Lipolase) in the synthesis of the drug pregabalin?

I am studying the synthesis of a drug pregabalin, for which both chemical and bio-catalysts are used. Using a biocatalyst is way better than chemical route, as explained here. In fact, The invention ...
0
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0answers
9 views

Drabkin Method for Hemoglobin Determination

Good evening, I have done several measurements of whole blood diluting it in Drabkin's solution. I need to plot calibration curve but I don't know how to. The concentration calculation is done by this ...
2
votes
2answers
89 views

Lowest CAS Registry Number on Record

I've been looking for a while and I still can't get a straight answer. I just need to know the lowest CAS Registry Number on record and the corresponding chemical.
4
votes
1answer
85 views

What is 'equality' of chemical bonds?

I was trying to solve a test series and I saw this question: "Why all $\ce{C-O}$ bonds in $\ce{CO_3^2-}$- are equal but not in $\ce{H2CO3}$?" I am completely confused by this question.
2
votes
2answers
46 views

Does dissociation require energy to occur?

I assume spontaneous separation to ions of salt solution (or acid) requires energy to occur, right? Where does that energy come from? Is it from the heat of the solution? Now, if someone devised a ...
0
votes
1answer
15 views

Alkaline and Bases

I learned about acids and bases in the latest chapter. And I saw that my textbook sometimes write alkaline and sometimes it write base. For me, alkaline and bases are metal oxides and metal hydroxide. ...
2
votes
1answer
22 views

How do I achieve same crystallinity when cooling polymers?

I am trying to make "films" of polyethylene glycol by melting them, pouring them into a mold and then cooling the mold down. The plan is to do this with different molecular weights. The problem is ...

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