instruction stringlengths 15 21.8k |
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It seems odd to me that this would be the case, but it also seems odd that it wouldn't.
Imagine a mechanism for a (forward) reaction that includes a slow reversible step and a fast irreversible step:
> A <-> B (slow) <br />
> B -> C (fast)
If the second step is irreversible, it's presumably going to be highly u... |
Can reversible reactions proceed by different mechanisms in the forward and reverse directions? |
I've read that active mass of solids and pure liquids is considered unity. I'm 100 percent sure there is some misunderstanding. I know that concentration of solids doesn't change during the course of reaction, but it shouldn't necessarily be unity either. Consider graphite for example. It's density is $0.00226\pu{g/L}$... |
I've read that active mass of solids and pure liquids is considered unity. I'm 100 percent sure there is some misunderstanding. I know that concentration of solids doesn't change during the course of reaction, but it shouldn't necessarily be unity either. Consider graphite for example. It's density is $0.00226\pu{g/L}$... |
Which one of the three compounds has the highest C-C bond stability?
ethane has sp3 hybridisation so less s character and lesser Electronegativity compared to ethyne. Ethyne has high s character and high Electronegativity. so its covalent character should be strong and be having more stability right?
Some onlin... |
Why are moles written with 'mol' as opposed to something which is easier to write with one character, or even two? |
I have two crystal structures, one in R3m and one in Cm symmetry. Both structures also differ in stoichiometric ratios, $ABC_4$ and $A_2B_2C_8$, respectively. Both structures look nigh on identical, with the exception of double the amount of atoms in one than the other.
How would I go about manually changing the sym... |
This is a question in my textbook. Given in the question that the volume is constant so how are we going to find qp. Since it's a bomb calorimeter so pressure isn't constant. Is the question wrong? |
>In a bomb calorimeter, cyanamide was subjected to combustion at constant volume, and the heat evolved was found to be $\pu{742.7 KJ}$ at $\pu{25 ^\circ C}$. Find qp.
This is a question in my textbook. Given in the question that the volume is constant so how are we going to find qp? Since it's a bomb calorimeter so ... |
>In a bomb calorimeter, cyanamide was subjected to combustion at constant volume, and the heat evolved was found to be $\pu{742.7 KJ}$ at $\pu{25 ^\circ C}$. Find $q_p$.
This is a question in my textbook. Given in the question that the volume is constant so how are we going to find $q_p$? Since it's a bomb calorimet... |
Your question is hard to answer because it lacks a lot of information. $Cm$ (IT #8) belongs to the monoclinic which does not say anything about the threefold symmetry axes present in $R3m$ (IT #160). But it is not unheard to transfer a monoclinic model into one that belongs to the trigonal / rhombohedral system.
... |
so I was doing this question and I have some questions about what I did. Firstly am I correct to say that the concordant results = 24.1 cm^3 because there are 2 of these values. From this I then calculate that M = 32.9 however this can not be true, so what have I done wrong? [![enter image description here][1]][1]
... |
No. Each mole of the compound contains 6 moles of oxygen atoms, and has a mass of about 6 * 16 grams. You don’t have a mole, so use proportional reasoning to determine the actual mass in the sample.
To help to understand why it is simply a factor 6 and does not depend on the total number of atoms in the compound, pe... |
I've read that active mass of solids and pure liquids is considered unity. I'm absolutely sure there is some misunderstanding. I know that concentration of solids doesn't change during the course of reaction, but it shouldn't necessarily be unity either. Consider graphite for example. It's density is $0.00226\pu{g/L}$
... |
Does anyone know if it is possible or if there are any protocols for amide coupling in water (and not a normal polar aprotic solvent like DMSO, DCM, ACN, etc.)? |
How can we do amide coupling reaction in water? |
There is a solution with two chemical species, A and B. Given the equilibrium dissociation constant
$
k_D=\frac{[A][B]}{[AB]}
$
how do I relate the mean dissociation time $t_{off}$ to $k_D$, and initial reagent concentrations, assuming that the reaction time it takes for A and B to bind is much lower than the d... |
How do I compute the mean dissociation time from the dissociation constant, assuming instantaneous binding reaction rate? |
I'm writing a computer program to help a factory produce bottles of mixtures. A mixture is usually alcohol, water and some other stuff, like menthol. But could also be water and NaOH and some oils (think schampoo).
My basic understanding is that if one bottle is 500 ml and contains:
50% water
45% alcohol
5% oils
... |
Are all mixtures linear? |
I'm writing a computer program to help a factory produce bottles of mixtures. A mixture is usually alcohol, water and some other stuff, like menthol. But could also be water and NaOH and some oils (think schampoo).
My basic understanding is that if one bottle is 500 ml and contains:
50% water
45% alcohol
5% oils
... |
The limit of detection ($LOD$) for an analytical method can be derived from its calibration curve using the following equation:
$$ LOD = {\dfrac{(3.3 \cdot {\sigma_
\mathrm{resids}})} {m}} \tag{1} $$ [see reference at bottom]
where:
- $ \sigma_\mathrm{resids} $ is the standard deviation of the residuals of t... |
I've read that active mass of solids and pure liquids is considered unity. I'm absolutely sure there is some misunderstanding. I know that concentration of solids doesn't change during the course of reaction, but it shouldn't necessarily be unity either. Consider graphite for example. It's density is $2260\pu{g/L}$
$$... |
Is there any advanced theory than MOT? |
I am currently learning about Jahn-Teller distortions. For elongation I wondered why the d orbitals with z component are DESTABILISED When the metal ligand bonds are getting longer? I thought a longer bond would mean a less efficient overlap of the d orbital on the transition metal with the orbital on the ligand? And i... |
Why does the glycosidic bond between sugars is always between the anomeric carbon? |
The nonlinearity of volumetric additions can be addressed theoretically. However, in practice, calculating how much material is needed to fill 1000 500 mL bottles containing 50% water 45% alcohol 5% oils (% by weight), can be addressed for one formulation by making a small batch and determining specific gravity. In pra... |
It is somewhat surprising to me that there is almost no data about solubility if potassium silicate in water under normal conditions. The only thing I was able to find is the following:
<0.336 g/L @ 25ΕC, increasing
to 300 g/L @ 80ΕC. Once
dissolved, material will not
precipitate out
However, it is not clea... |
Why is the glycosidic bond between sugars always between the anomeric carbon? |
>Which one of the three compounds has the highest $\ce{C-C}$ bond stability?
Ethane has $\mathrm{sp^3}$ hybridisation so less $\mathrm{s}$-character and lesser electronegativity compared to ethyne. Ethyne has high $\mathrm{s}$-character and high electronegativity. so its covalent character should be strong and be h... |
Today I used a 12 volt power supply to observe electrolysis of water.
The leads coming from the power supply had clamps on their ends.
When in water bubbles started evolving on the clamps.
Does this damage the clamps in any way ?
Is there something I should put in the clamps to improve this experiment ?
|
Does electrolysis of water alter the electrodes? |
The title says it all really.
I thought it would be acetylacetonatobipyridinecopper(II) tetraphenylborate. Is this correct? I feel as though it looks a bit clumsy and wasn’t sure if I was supposed to include as (2,2-bipyridine)? Is it ok to use brackets like this for naming a coordination compound the IUPAC way or i... |
Today I used a 12 volt power supply to observe electrolysis of water.
I mixed table salt into the water, nothing else.
The leads coming from the power supply had clamps on their ends.
When in water bubbles started evolving on the clamps.
Does this damage the clamps in any way ?
Is there something I shoul... |
[![enter image description here][1]][1]
I have trouble understanding as to what the last part of the increase in liquid level mean. I believe this is the foam formed after the fermentation? I am calculating for the pressure but I have trouble as to what volume should I use to find the moles since I don't understand ... |
I am currently going through *molecular orbital theory*(MOT), I should appreciate it's a very nice theory and it's helping me to fill the gaps of *hybridization* and *valance bond theory*(VBT). But I am unaware about it's limitations seemingly it's the most advanced theory and have the capability of explaining everythi... |
I am currently going through *molecular orbital theory*(MOT), I should appreciate it's a very nice theory and it's helping me to fill the gaps of normal *hybridization* concepts and *valance bond theory*(VBT). But I am unaware about it's limitations seemingly it's the most advanced theory and have the capability of exp... |
I wish to use lauryl glucoside in the solution of citric acid. I tried to add it to 5% w/w solution of citric acid in water but after about 24h in the concoction which was previously clear I observed a kind of sediment. It looked like a "white smoke" disspersed in the clear liquid. I wonder whether it can be the effect... |
Is lauryl glucoside stable in low pH? |
My attempt:
$$\text{equivalent of metal oxide = equivalent of H}_2$$
$$\frac{1.80\space\text{gm}}{\text{E gm/eq.}} = \frac{833\text{ ml}}{22400\text{ ml/eq.}}$$
$$\text{E}=48.4\text{ gm/eq.}$$
Now, since $$\text{eq. wt. of oxide = eq. wt. of metal + eq. wt. of oxygen}$$
$$\text{48.4 = 8 + E}_M \rightarrow \text{... |
1.80 gm of a metal oxide required 833 ml of hydrogen at NTP to be reduced to its metal. What are the equivalent weights of the oxide and the metal? |
If we are creating a precipitate of (say) Barium Sulfate from a solution of Barium Chloride mixed with Sodium Sulfate, what determines the particle size?
I assume one of the factors will be concentration of reactants in the solutions, but what else? |
If there is a Na and cl in solid form , There will be atoms inside of them.How do they lose electrons ?.We know solid body has a structure and covering.Just like you can touch is the covering of table that is its outer part.Do we touch the electrons or the atom as we touch a body?.When a body loses electrons from a bod... |
How does a body lose electrons? |
My attempt:
$$\text{equivalent of metal oxide = equivalent of H}_2$$
$$\frac{1.80\space\text{g}}{E \text{ g/eq.}} = \frac{833\text{ ml}}{22400\text{ ml/eq.}}$$
$$\text{E}=48.4\text{ g/eq.}$$
Now, since $$\text{E}_{oxide} = \text{E}_{oxygen} + \text{E}_{metal} $$
$$\text{48.4 = 8 + E}_{metal} \rightarrow \text{E}... |
It is somewhat surprising to me that there is almost no data about solubility of potassium silicate in water under normal conditions. The only thing I was able to find is the following:
> <0.336 g/L @ 25ΕC, increasing to 300 g/L @ 80ΕC. Once dissolved,
> material will not precipitate out
>
> [Technical lDocum... |
Is it possible for a molecule to absorb and emit at the same wavelength? What is the reason behind it?
I’m working on charged Tin porphyrins and got the excitation and emission (fluorescence) wavelength around 400nm. |
Absorption and Emission at same wavelength? |
I've studied that when $1,3-dibromopropane$ (or in general any halogen, not just bromine) is heated with $Zn$ dust, the electrons produced cause the halogens to break away homolytically and two free radicals are formed. These free radicals then combine to form cyclopropane.
[![enter image description here][1]][1]
... |
There is a solution with two chemical species, A and B. Given the equilibrium dissociation constant
$
K_D=\frac{[A][B]}{[AB]}
$
how do I relate the mean dissociation time $t_{off}$ to $K_D$, and initial reagent concentrations, assuming that the reaction time it takes for A and B to bind is much lower than the d... |
I've studied that when 1,3-dibromopropane (or in general any halogen, not just bromine) is heated with Zn dust, the electrons produced cause the halogens to break away homolytically and two free radicals are formed. These free radicals then combine to form cyclopropane.
[![enter image description here][1]][1]
My ... |
I am currently going through *molecular orbital theory*(MOT), I should appreciate it's a very nice theory and it's helping me to fill the gaps of normal *hybridization* concepts and *valance bond theory*(VBT). But I am unaware about it's limitations seemingly it's the most advanced theory and have the capability of exp... |
Is there any theory more advanced than MOT? |
It is somewhat surprising to me that there is almost no data about solubility of potassium silicate in water under normal conditions. The only thing I was able to find is the following:
> <0.336 g/L @ 25ΕC, increasing to 300 g/L @ 80ΕC. Once dissolved,
> material will not precipitate out
>
> [Technical Docume... |
I can't present you a movie of electron interactions, but maybe a fuzzy picture. Imagine a metal body (start with copper): the atoms are held in a solid structure - in a sea of electrons! Those loose electrons can be pushed around easily, so we can make wires out of copper and transmit electricity thru them. If you put... |
In the expression of equilibrium constant, each concentration term is raised to the power of their stoichiometric coefficient. But this could affect the equilibrium constant.
For example, we can write the chemical equation of ammonia in these two ways
$$\ce{N_2(g) + 3H_2(g)<=>2NH_3(g)}$$
and
$$\ce{\frac{1}{2}N_2... |
>A metal oxide ($\pu{1.80 g}$) required $\pu{833 ml}$ of hydrogen at NTP to be reduced to its metal. What are the equivalent weights of the oxide and the metal?
**My attempt:**
$$\text{equivalent of metal oxide = equivalent of } \ce{H2}$$
$$\frac{\pu{1.80 g}}{E \ \pu{g/eq}} = \frac{\pu{833 ml}}{\pu{22400 ml/eq}}... |
I've been trying to find out about this for some time now and when I searched online, I couldn't get any proper reasons.
My question is: **What is the reason for the characteristic colours of elements?** For eg: Why does Sodium have a characteristic colour of silvery-white?
Is there any solid scientific reason ... |
What is the reason behind the characteristic colours of elements? |
I am currently learning about Jahn-Teller distortions. For elongation I wondered why the d orbitals with z component are Stabilised When the metal ligand bonds are getting longer? I thought a longer bond would mean a less efficient overlap of the d orbital on the transition metal with the orbital on the ligand? And if ... |
*The fluorescence excitation spectra show the change in fluorescence intensity as a function of the wavelength of the excitation light.*
I'm interested in the certain physical implications of the above.
Does that mean, that at the wavelength of excitation maximum the most of the molecules get excited? Or do they... |
Room-temperature superconductivity has finally been demonstrated, as reported by [Quanta][1] (and others), with the caveat that it requires compression of the substrate at nearly 2 Mbar. Obviously, this is an impractically high pressure, but if a different material were found that only required a much lower pressure, ... |
Good books have been written to explain all the implications of fluorescence spectroscopy. There is no universal answer because of the complications of the experiment.
In general there are atomic spectra and molecular spectra.
* Atomic spectra tend to give line spectra.
* For molecules however the binding energy ... |
> The fluorescence excitation spectra show the change in fluorescence intensity as a function of the wavelength of the excitation light. Does that mean, that at the wavelength of excitation maximum the most of the molecules get excited? Or do they just emit more photons per molecule per unit time?
You have understan... |
> The fluorescence excitation spectra show the change in fluorescence intensity as a function of the wavelength of the excitation light. Does that mean, that at the wavelength of excitation maximum the most of the molecules get excited? Or do they just emit more photons per molecule per unit time?
You have understan... |
I'm a grade 12 student trying to understand redox reactions. What's the equation for the reduction of water? The back of my textbook says:
2H20 + 2e -> H2 + 2OH-
I get that this makes sense, but I have no idea how to derive it myself. Any help would be appreciated!
|
What is the equation for the reduction of water? |
> The fluorescence excitation spectra show the change in fluorescence intensity as a function of the wavelength of the excitation light. Does that mean, that at the wavelength of excitation maximum the most of the molecules get excited? Or do they just emit more photons per molecule per unit time?
You have to unders... |
I'm a grade 12 student trying to understand redox reactions. What's the equation for the reduction of water?
The back of my textbook says: $\ce{2H2O + 2e- -> H2 + 2OH-}$
I get that this makes sense, but I have no idea how to derive it myself. Any help would be appreciated!
|
As an artist, when disposing of a paper towel or cotton rag containing oil paint, turpentine, odorless turpentine substitute or mineral spirits at the end of a painting session, I generally pour water over the paper towel or cotton rag to reduce its flammability. Sometimes I rinse out the paper towel or rag in the sink... |
Equivalents are part and parcel of Indian chemical education. I don't think college chemistry is going to be updated soon anytime there. I recently heard a complaint by a company to the chemistry chair in an American University. They said that your students do not understand normality! Please teach these concepts to yo... |
The internal pressure is derived by differentiating internal energy with respect to the natural variable in one term while holding the unnatural variable in the other term constant.
$$dE = T dS - PdV$$
becomes
$$(\frac{\partial E}{\partial V})_T = T(\frac{\partial S}{\partial V})_T - P$$
Then, using the re... |
I am still a first year student; I was asked in the exam to identify the meso comound out of some choices. The answer key said that the compound below is meso. But I see no plane of symmetry here. Am I wrong or the question? I hope someone clarifies please. Sorry if the question was super silly.
[![supposed meso compu... |
Reaction that happens at 380k Ds(sys)=-130. Cp(c2h4)=43.6. Cp(c2h5OH)65.9. Cp(h20) 33.6. I need to calculate the dS for reaction
C2H4(g) + H2O(g) <---> C2H5OH(g)
I really have no try, i can calculate it if i was given the entropies for each reactant/product and do products-react... |
Entropy of reaction from these givens? |
It seems odd to me that this would be the case, but it also seems odd that it wouldn't.
Imagine a mechanism for a (forward) reaction that includes a slow reversible step and a fast irreversible step:
> $\ce{A <=> B (\text{slow})}$</br> $\ce{B -> C (\text{fast})}$
If the second step is irreversible, it's presumab... |
It seems odd to me that this would be the case, but it also seems odd that it wouldn't.
Imagine a mechanism for a (forward) reaction that includes a slow reversible step and a fast irreversible step:
> $$
\begin{align}
\ce{A &<=> B} &\quad &\text{(slow)} \\
\ce{B &-> C} &\quad &\text{(fast)}
\end{align}
$$
... |
Reaction that happens at 380 Kelvin
Ds(sys)=-130
Cp(c2h4)=43.6
Cp(c2h5OH)=65.9
Cp(h20)=33.6
I need to calculate the dS for reaction:
C2H4(g) + H2O(g) <---> C2H5OH(g)
I really have no try, i can calculate it if i was given the entropies for each reactant/product and do products-reactant. but can someone gi... |
The internal pressure is derived by differentiating internal energy with respect to the natural variable in one term while holding the unnatural variable in the other term constant.
$$\mathrm dE = T\,\mathrm dS - P\,\mathrm dV \tag{1}$$
becomes
$$\left(\frac{\partial E}{\partial V}\right)_T = T\left(\frac{\pa... |
First of all: Reduction is just a fancy way of saying "gain of electrons".
The posed question is 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 ox... |
First of all: Reduction is just a fancy way of saying "gain of electrons".
The posed question is 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 ... |
[![enter image description here][1]][1]Reaction that happens at 380 Kelvin
Ds(sys)=-130
Cp(c2h4)=43.6
Cp(c2h5OH)=65.9
Cp(h20)=33.6
I need to calculate the dS for reaction:
C2H4(g) + H2O(g) <---> C2H5OH(g)
I really have no try, i can calculate it if i was given the entropies for each reactant/product and d... |
Reaction that happens at 380 Kelvin
$\begin{align} \Delta S^\circ _{sys} &=\pu{-130 J/molK}\\
C_p(\ce{C2H4})&=\pu{43.6 J/molK}\\
C_p(\ce{C2H5OH})&=\pu{65.9 J/molK}\\
C_p(\ce{H2O})&=\pu{33.6 J/molK} \end{align}$
I need to calculate the $\Delta S $ for reaction:
$$\ce{C2H4(g) + H2O(g) <=> C2H5OH(g)}$$
I ... |
>At equilibrium, everything that
$G$ depends on is constant.<br>
The Gibbs' free energy may have been given to you without really emphasizing that it is actually a function of temperature, pressure, and the
moles of involved reactants and products:
$$G=f(T, p, n_i)$$When we are at equilibrium, we really mean al... |
Why isn't standard Gibbs energy zero at equilibrium? |
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... |
Not sure whether this might be a Superuser or StackOverflow question... but I hope some Chemist can help me with this.
I have an Excel table with cells which contain comments "by Cambridge Soft". I assume that these comments somehow contain the ChemDraw data of the structure. It seems to be ASCII-characters only.
... |
How to convert Excel comments to ChemDraw .cdx? |
[![enter image description here][1]][1]
I have trouble understanding as to what the last part of the increase in liquid level mean. I believe this is the foam formed after the fermentation? I am calculating for the pressure but I have trouble as to what volume should I use to find the moles since I don't understand ... |
>Which one of the three compounds has the highest $\ce{C-C}$ bond stability?
Ethane has $\mathrm{sp^3}$ hybridisation so less $\mathrm{s}$-character and lesser electronegativity compared to ethyne. Ethyne has high $\mathrm{s}$-character and high electronegativity. Therefore the covalent character of $\mathrm{sp^3-s... |
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... |
Because you find these entries in a Excel workbook, it is likely that this spreadsheet was created with Chemdraw's add-in for Excel ([company's demo][1]) to embed chemical formulae:
[![enter image description here][2]][2]
([source][3]).
to provide a bridge between the two worlds to display chemical libraries (... |
PQ Corporation sells many compositions of sodium and potassium silicates. Concentrations of potassium silicate range up to 40% in water.
The product literature includes pH, viscosity, SDS and just about every measurable property you could ask for. The reason such data are not in academic literature or book form is p... |
Is it possible to obtain Potassium silicate `(K₂SiO₃)` from Sodium silicate `(Na₂SiO₃)` without using expensive lab equipment such as furnaces etc.?
For example, Calcium silicate may be obtained using the following exchange reaction:
$$\ce{CaCl2 + Na2SiO3 -> CaSiO3 v + 2NaCl}$$
Substituting Calcium chloride w... |
Is it possible to obtain Potassium silicate ($\ce{K2SiO3}$) from Sodium silicate ($\ce{Na2SiO3}$) without using expensive lab equipment such as furnaces etc.?
For example, Calcium silicate may be obtained using the following exchange reaction:
$$\ce{CaCl2 + Na2SiO3 -> CaSiO3 v + 2NaCl}$$
Substituting calcium... |
I wondered what modifications there would be to the Beer Lambert law to find the molar extinction coefficients for the solution if the solvent contained the ligands which bind to the metal centre of a metal compound (ie 2 ligands add along the z axis only) and the complex was tetragonal? |
I used a soft silicon hose to carry ammonia at ~70C. I was surprised to later find the hose had hardened.
A quick materials compatibility search for silicon had given me a lot of info but an "I" (standing for "Insufficient Information") for ammonia. I wrongly assumed it would be ok.
What happened? What was prod... |
What is the product of ammonia reacting with silicon? |
>At equilibrium, everything that $G$ depends on is constant.<br>
The Gibbs' free energy may have been given to you without really emphasizing that it is actually a function of temperature, pressure, and the moles of involved reactants and products:
$$G=f(T, p, n_i)$$ When we are at equilibrium, we really mean all of ... |
What is the product of ammonia reacting with silicone? |
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