All Questions

Filter by
Sorted by
Tagged with
5
votes
1answer
431 views

Can a solid and liquid be miscible?

To be specific, what I mean is: is the following situation possible? At given temperature T, there are two substances, X and Y, such that pure X is a solid, pure Y is a liquid, and X and Y mix to form ...
9
votes
2answers
3k views

Why does nitrous acid exhibit (unexpectedly) different bond angles?

Data Point 1 - quantum chemical calculations http://nzc.iap.ac.cn/uploadpdf/Wang_et_al._CSB_2007a.pdf Key points in paper: There is some sort of interaction between the hydrogen and the terminal ...
6
votes
1answer
919 views

Applying the Le Chatelier principle

I am having issues understanding the consequence(s) of a decrease in pressure on a chemical reaction. I have understood that when we increase the pressure, the side having more number of moles wants ...
3
votes
2answers
857 views

Which is the correct way to name pentan-3-one?

I have seen this organic compound named in two different ways. According to some sources it is written pentan-3-one.. Other sources call it 3-pentanone. Which one is correct?
6
votes
2answers
16k views

Why are methanol flames less visible than other flames?

The combustion of methanol tends to generate flames that are less visible than the flames generated by the combustion of other substances? My guess is that methanol burns quickly as it has a ...
5
votes
2answers
7k views

Why is formic acid considered an acid if it is a reducing agent?

My understanding was that since the acceptance of Lavoisier's revised Easter Memoir of 1778, all acids were understood to be oxidising agents.* However, formic acid is often listed as a reducing ...
18
votes
5answers
10k views

Turn lead into gold via radioactive decay

I was looking at the isotope's table and noticed that one of lead's isotopes can actually turn into stable gold through the following mechanism: $$\ce{_{82}^{197}Pb -> _{81}^{197}Tl -> _{80}^{...
1
vote
1answer
13k views

Determining the group number of an element from its successive ionization energies

The successive ionization energies of an unknown element X are: 1st - 9534; 2nd - 11790; 3rd - 13683; 4th - 15309; 5th - 16458. To what group number does X belong? There aren't any significant ...
2
votes
0answers
165 views

Why don't plus one oxidation state metals form stable complexes with hydroxide ion?

For example, why doesn't AgOH exist as a stable compound? I read that it rapidly decomposes to silver oxide and water. $\ce{2AgOH -> Ag2O + H2O}$ $~~~~~~~~~pK_{decomposition}= 2.875$ http://...
2
votes
1answer
1k views

How to create the equivalent of luminol for a compound?

How would you go about creating a compound, like luminol, that would visibly react with monomorine I (5-methyl-3-butyloctahydroindolizine) on a household surface (like a kitchen floor)? It is ok if ...
3
votes
1answer
1k views

Can ionic and atomic radii be compared?

Can ionic and atomic radii be compared? For example, this is a common problem in some intro chem courses: Rank the following from smallest to largest: sodium ion, magnesium ion, neon, fluoride, ...
-2
votes
1answer
216 views

How to use signicant figures?

I am confused about significant figures. In a teaching video, the teacher showed this math: $$ 22.2 + 22.2 + 30.10 + 30.10 = 104.6$$ This is, of course, the actual answer, but in using significant ...
0
votes
2answers
1k views

Can I use Sunflower oil to make soap?

When reading about making glycerine soap, the recipes suggested to melt animal fat and mix it with $\ce{NaOH}$. Could I use Sunflower oil instead? Or a olive oil for nice flavor? Is heating necessary ...
4
votes
1answer
123 views

Where can I find Equilibrium Constants?

When trying to develop mathematical models to show the concentration in a reaction, where can one find a database or good source of known equilibrium constants if it is not necessarily very convenient ...
1
vote
1answer
731 views

Why does lactulose turn dark?

Why does the standard 10gm/15ml lactulose solution turn dark when exposed to heat above 30 degrees Celsius? This is probably a simple question. It is funny that the warnings/important information on ...
0
votes
1answer
4k views

What is the pH of a solution of HCOONa and HNO3?

Calculate the pH of an aqueous solution obtained by mixing 20 ml of $\ce{HCOONa}$ 0,1 M and 5 ml of $\ce{HNO_3}$ 0.2 M. ($K_\mathrm a$ of $\ce{HCOOH}$ $= 10^{-4}$) My try: The number of the ...
3
votes
2answers
13k views

Is it true that a pH higher than the pKa of an acid make the H automatically disassociate?

Will the hydrogen atom always disassociate if the pH of the solution is higher than the pKa of the acid?
4
votes
1answer
3k views

Most negative and most positive value for proton chemical shifts

What are the most negative and the most positive values for proton chemical shifts recorded till present?
10
votes
1answer
4k views

Under what circumstances is working in the chemistry lab hazardous to health in the long term? [closed]

I would like to know when working in the Chemistry lab would be hazardous to health in the long term. Because as everyone who worked in the chemistry lab knows that they would be handling many ...
20
votes
1answer
441 views

Can a multi-species system oscillate around equilibrium?

In reading about chemical oscillations such as those that occur in the Belousov–Zhabotinsky reaction (BZ), it's often reported that these reactions were initially not taken seriously, because of a ...
3
votes
4answers
5k views

Causes of reversible reaction

It is generally said that reactants react so that they can achieve a lower energy state. Then why does a reversible reaction occur in the first place? Since turning reactants into products increases ...
1
vote
2answers
82 views

How can I detect a specific molecule on a surface?

Based on the comments and answers, this question wasn't very clear, so I have completely overhauled this question to make it much clearer in another post: How to create the equivalent of luminol for a ...
2
votes
1answer
833 views

How to calculate the heat absorbed by a reversible process?

Given a nonideal substance inside a box with diathermal walls, the pressure is increased reversibly. How do you calculate the heat absorbed? I assume we use dE = dq + dw = dq - pdV => dq = dE + pdV ...
5
votes
1answer
327 views

Problems with thermodynamic derivatives

How is the following true? $$\left ( \frac{∂S}{∂P} \right )_{T}=\frac{-C_{P}}{T}\left ( \frac{∂T}{∂P} \right )_{S}$$ I know that $$C_{P}=T\left ( \frac{∂S}{∂T} \right )_{P}$$ which means the right-...
3
votes
1answer
110 views

Residual stress in polymer coatings

A paper talks about the residual stress when coating polymers. It says that residual stress is the sum of the "heat stress" (due to the difference in thermal expansion coefficients) and the "shrinkage ...
0
votes
2answers
2k views

Determining boiling point on a created temperature scale

1.Assume that you construct a thermometer using gallium as the fluid instead of mercury, and that you define the melting point of gallium as 0 °G and the boiling point of gallium as 1000 °G. What is ...
1
vote
1answer
69 views

How do scientists check which kind of unit cell is present in a crystal?

There are many types of unit cells like: Tetragonal Monoclinic Orthorhombic Rhombohedral Hexagonal Triclinic Cubic But how do scientists identify the type when a ...
5
votes
2answers
585 views

How do people check the type of defect in a crystal?

There are many types of defects like Vacancy Interstitial Schottky Frenkel Non-Stoichiometric Alien Impurities But given a sample, how do scientists know which kind of defect is present in it [...
5
votes
1answer
5k views

How to calculate the equilibrium composition after a change in partial pressure of one component?

Question Ammonium carbamate dissociates as shown below. $$\ce{NH2COONH4 (s) -> 2NH3 (g) + CO2 (g)}$$ In a closed vessel containing ammonium carbamate in equilibrium with ammonia and carbon ...
10
votes
1answer
3k views

What is C2H5-O-CH=CH2?

Someone painted an original graffiti: source I wonder what kind of reaction was depicted; what's that product substance? The graffiti reads: $\ce{C2H2 + C2H5OH -> C_2H_5-O-CH=CH_2}$ Does it ...
2
votes
0answers
761 views

Is superglue a good thermal insulator?

How good of a thermal insulator is superglue compared to other materials like ceramics, plastics, and metals? I know this might not seem like a chemistry question, but I was hoping someone here could ...
1
vote
1answer
750 views

What is the length of a unit cell of CuCl assuming that it is fcc?

The density of $\ce{CuCl}$ is given – $x\ \mathrm{g/cm^3}$ The crystal structure is assumed to be fcc. My teacher is claiming the we can apply the formula $$\rho=\frac{Z \cdot M}{a^3 \cdot N_\mathrm ...
3
votes
1answer
11k views

What properties does a solvent with a high dielectric constant have?

My professor commented that water has a higher dielectric constant than alcohol. Okay, but on what basis? He didn't elaborate; he asked us which one seemed "more electric" and most answered water. ...
11
votes
1answer
2k views

Coefficients and Parameters for contracted Gaussian basis sets

I'm trying to write a program to calculate fixed-point Hartree-Fock level energies of molecules (for my amusement) and everything makes sense but this. I've been agonizing over this for almost 3 hours ...
3
votes
1answer
1k views

What are the priorities for substituent groups on a cyclohexane?

I was wondering about this specific scenario: If you have a cyclohexane, for example, and the cyclohexane has two consecutive substituent groups, for example a methyl group and an ethyl group, how do ...
1
vote
1answer
2k views

Rate-determining step and steady state approximation failure

1) When can't the rate-determining step be applied, and why? How do you recognize these cases? 2) When can't the steady state approximation be applied, and why?
3
votes
2answers
528 views

Detection of magnesium in a buffer?

I have a PolyA tailing kit for putting PolyA tails on the 3' end of RNA. The kit comes with a proprietary 5X buffer and a 25mM MnCl2 solution, and in the standard set up I use 20uL of 5X buffer and ...
2
votes
2answers
195 views

Using non-food grade NaOH for pH control

I would like to use non-food grade $\ce{NaOH}$ for $\ce{pH}$ water treatment. Any problem with this mixing with water that contains iron? The $\ce{NaOH}$ will be pumped into a well. As a $25\%$ ...
13
votes
3answers
1k views

Biological Consequences of Asteroid Mining—Death by Isotope?

It's been documented that NASA hope to capture an asteroid in 2025, and have subsequent aims to mine that asteroid. If if this is successful, we would expect other asteroids to be mined in the future. ...
17
votes
4answers
5k views

How does sulfuric acid dehydrate sugars?

I know sugars have $\ce{-OH}$ groups, and that sulfuric acid is a strong acid. What I'm failing to see is how exactly sulfuric acid dehydrates sugars. Does it protonate the hydroxyl groups, making ...
1
vote
1answer
1k views

Sulfur Trioxide - Ionic Character

I am told that the sulfur trioxide molecule exhibits charge separation because of poor p-orbital overlap. Sulfur's 3p orbitals are much bigger than oxygen's 3p orbitals, and thus the $\ce{S=O}$ bond ...
7
votes
2answers
33k views

Amount of Phenolphthalein required

We just had chemistry practical few days a go. The topic was strong acid-base titration, in which we had to find the normality and concentration of $\ce{HCl}$. My teacher instructed me to add 2 drops ...
1
vote
1answer
806 views

Nitration of Aromatic Compounds

I am told by Dr. Klein that in the nitration of benzene, hydrogen sulfate anion acts as the base and deprotonates the sigma complex. My question is why would the hydrogen sulfate anion be doing the ...
3
votes
1answer
86 views

How can I measure carcinogenic risks of an M-ENDO-Agar LES substrate after heat destruction?

I'm about to conduct a study of possible toxic traces from the substance M-ENDO-Agar LES in substrate after destruction with heat (I think it is 160℃) for 180 minutes. The substance is carcinogenic. ...
9
votes
3answers
9k views

Why is chloride oxidised instead of water in copper chloride electrolysis?

For the Electrolysis of Copper Chloride: Cathode: $\ce{Cu^{2+} + 2e- <=> Cu}$ Anode: $\ce{2Cl <=> Cl2 + 2e- }$ I am confused about the reaction taking place at the anode. Wouldn't $\ce{...
-1
votes
3answers
3k views

Delocalization of positive charge

How is positive charge delocalized? I understand how negative charge can be delocalized. Electrons are mobile and they can move around. But what about positive charge? For example, consider this ...
1
vote
1answer
3k views

How many empty orbitals do elements have?

A student was contemplating a question regarding elements with "no empty valence orbitals." An argument was made that elements all have infinite number of valence orbitals. Every atom basically ...
4
votes
3answers
2k views

Which has higher rate of hydrogenation - methyl propene or trans-2-butene?

Which has higher rate of hydrogenation- methyl propene or trans-2-butene? I know that cis-2-butene has a higher rate of hydrogenation than both of these due to steric reasons, but here, both of these ...
9
votes
2answers
18k views

Is the valency of carbon satisfied in graphite?

Graphite has hexagonal parallel planes. In a hexagonal structure the carbon atom has three bonds. Since the valancy of carbon is 4 is the valency satisfied in graphite?
15
votes
3answers
6k views

Why is magic acid a superacid?

The above is a representation of magic acid. The left part is the acid; the right part is the solvent. Why would this combination make for a particularly good acid? The left part looks like a ...

15 30 50 per page
1 577 578 579 580 581 659