instruction stringlengths 15 21.8k |
|---|
The difference between the Enthalpy of Reaction $\Delta_{\mathrm{r}} H$ and the Standard Enthalpy of Reaction $\Delta_{\mathrm{r}} H^{\ominus}$
------------------------------------------------------------------------
The standard value is not related to a standard temperature (although Standard Enthalpies of Reacti... |
The difference between the Enthalpy of Reaction $\Delta_{\mathrm{r}} H$ and the Standard Enthalpy of Reaction $\Delta_{\mathrm{r}} H^{\ominus}$
------------------------------------------------------------------------
The standard value is not related to a standard temperature (although Standard Enthalpies of Reacti... |
For example, this reaction: $$\ce{2NaOH + H2SO4 -> Na2SO4 + H2O}$$
Suppose both concentration are 1M (standard condition). There is 0.02 mol (20$cm^3$) of $\ce{NaOH}$, and 0.01 mol (10$cm^3$) of $\ce{H2SO4}$. So neither reactant is the limiting reactant.
Well, I know one way is to find the standard enthalpy of f... |
I'm going to try out the transesterification of propylene carbonate and methanol. I know that the mechanism is as follows :
![enter Transesterification][1]
-What are the products yielded after the reaction?
-And which catalyst should I use? (reaction is happening at normal air pressure and at room temperature... |
I am not a chemist, I develop software. I'm hoping for a general explanation I can understand in order to assist me with a project I'm working on.
Customers viewing a product online such as peroxide see **97% (dry wt.), wet with 25% water**.
What does this mean? What would you expect the product to be int he form... |
The Lugol solution is a mixture of $(K^+ , I^- )$ and $I_2$ such that $I_{3}^-$ are formed by:
$I^- + I_2 \leftarrow I_{3}^{-}$
I know that the brown color comes from $I_2$, but in this solution one have $I_{3}^-$ not $I_2$, why is it brown?
When I mix Lugol with $H_2 O_2$ without the presence of $H_3 O^+$ the... |
Which reaction between Lugol and Hydrogen peroxide? |
I am not a chemist, I develop software. I'm hoping for a general explanation I can understand in order to assist me with a project I'm working on.
Customers viewing a product online such as peroxide see **97% (dry wt.), wet with 25% water**.
What does this mean? What would you expect the product to be in the form... |
The Lugol solution is a mixture of $(K^+ , I^- )$ and $I_2$ such that $I_{3}^-$ are formed by:
$I^- + I_2 \rightarrow I_{3}^{-}$
I know that the brown color comes from $I_2$, but in this solution one have $I_{3}^-$ not $I_2$, why is it brown?
When I mix Lugol with $H_2 O_2$ without the presence of $H_3 O^+$ th... |
I believe there is no general rule.
In your case (assuming you mean [this][1]) it is a solid. materials can have 25% and even more water and still be solids.
[1]: https://us.vwr.com/store/catalog/product.jsp?product_id=9898342 |
I need to find the ratio of a substance as it converts from a bicarbonate to a carbonate:
ex:
>Fe(HCO3)2 > FeCO3 + CO2 + H2O
>Fe(HCO3)2 / FeCO3 = 3/2 *using molar masses
But what if the substances aren't the same number of moles?
ex:
>2Fe(HCO3)2 > FeCO3 + CO2 + H2O
Would the ratio be:
>2Fe(HCO3)2 /... |
Law of Definite Proportion: Do the numbers indicating moles count? |
I need to find the ratio of a substance as it converts from a bicarbonate to a carbonate:
ex:
>$\ce{Fe(HCO3)2 -> FeCO3 + CO2 + H2O}$
>$\ce{Fe(HCO3)2} / \ce{FeCO3}$ = $3/2$ *using molar masses
But what if the substances aren't the same number of moles?
ex:
>$\ce{2Fe(HCO3)2 -> FeCO3 + CO2 + H2O}$
Would ... |
![enter image description here][1]
[1]: https://i.stack.imgur.com/k5bBn.png
Usually NaNO2 and HCl is used to make diazonium chloride. But, in this compound there are two amine groups adjacent to each other so I doubt whether diazonium chloride would form. Will the two amine groups react in between the reactio... |
Will this reaction lead to diazonium chloride? |
![enter image description here][1]
[1]: https://i.stack.imgur.com/k5bBn.png
Usually $\ce{NaNO2}$ and $\ce{HCl}$ is used to make diazonium chloride. But, in this compound there are two amine groups adjacent to each other so I doubt that diazonium chloride would form. Will the two amine groups react during the ... |
This looks like a homework question, so I won't give you the complete answer.
Convert one of the amine groups to the diazonium chloride. In addition to substitution reactions by loss of $\ce{N2}$, diazonium compounds will react with nucleophiles at the terminal nitrogen atom. The best known examples of this behavio... |
>The stoichiometric coefficients are important. They make sure you have a valid relationship between reactants and products that obeys the Law of Conservation of Mass.
As Jerry hints at in his comment, there is another fundamental law that you need to consider: [the Law of Conservation of Mass][2]. Matter cannot be ... |
I want to remove carbonate ions from dissolved potassium carbonate (potash) by letting an organic compound react with the carbonate ions - I don't have a very good knowledge of organic chemistry; but are there certain types of organic molecules that can react with these carbonate ions to form new compounds?
(and as ... |
Say you have NaOH and CH3COOH and want to make a buffer.
Theory teaches 6 mols of CH3COOH and half, 3 mols, of NaOH would be needed.
Then you'd be left with 3 mols of H2O, 3 mols of NaCH3COO and 3 mols of CH3COOH.
However, what if you mixed 3 mols of NaOH with 12 mols of CH3COOH? According to my calculations, yo... |
Why do buffers need to be composed of equal amounts of the acid and salt? |
Say you have $\ce{NaOH}$ and $\ce{CH3COOH}$ and want to make a buffer.
Theory teaches 6 mols of $\ce{CH3COOH}$ and half, 3 mols, of $\ce{NaOH}$ would be needed.
Then you'd be left with 3 mols of $\ce{H2O}$, 3 mols of $\ce{NaCH3COO}$ and 3 mols of $\ce{CH3COOH}$.
However, what if you mixed 3 mols of $\ce{NaOH}$ w... |
I'll try to figure out the color of every compound separately, but there is a strong interaction between them and the different parameters so this could be quite tricky:
- $I^+ , IO_3^-$ don't absorb in the visible region
- $I_3^-$ I think should be [red](http://rstarchem.weebly.com/experiment-ana2.html)
- $... |
I was under the impression that if I put a semi full bottle of vinegar in the freezer the water would freeze but the vinegar would not until a lower temp. Therefore I could remove the bottle after the water freezes and pour off the vinegar. Apparently the water and vinegar doesn't separate nicely before freezing so th... |
I'm interested in making a liquid freeze spray, for a fun science project. My only experience with this comes in spraying inverting canned air dusters, which spray a -60F mist/liquid (liquid if you spray while the can is inverted). I'd like to make a spray that I can store and use. And if it can't be stored more than a... |
How would one go about making a cheap freeze spray? |
"Magnesium has a very slight reaction with cold water, but burns in steam.
A very clean coil of magnesium dropped into cold water eventually gets covered in small bubbles of hydrogen which float it to the surface. Magnesium hydroxide is formed as a very thin layer on the magnesium and this tends to stop the reaction... |
Why do the reactions of Magnesium in steam and cold water differ? |
A solution prepared by dissolving 2.8 gm of lime, CaO in enough water to make 1.00 L of lime water (Ca(OH)2(aq.)). If solubility of Ca(OH)2 in water is 1.48 gm. The pH of the solution obtained will be:
[log 2 = 0.3, Atomic masses are Ca = 40 , O = 16, H = 1]
[Note : Ca(OH)2 is considered to be a weak base because... |
A box contains a mixture of small copper spheres and small lead spheres. The total volume of both metals is measured by the displacement of water to be 420cm3 and the total mass is 5.4kg.What percentage of the spheres are copper? |
A box contains a mixture of small copper spheres and small lead spheres. The total volume of both metals is measured by the displacement of water to be 420 cm$^3$ and the total mass is 5.4 kg.What percentage of the spheres are copper? |
Hi I am trying too do this problem:
A box contains a mixture of small copper spheres and small lead spheres. The total volume of both metals is measured by the displacement of water to be 420 cm$^3$ and the total mass is 5.4 kg.What percentage of the spheres are copper?
but I can't get the right answer. I tried ... |
A box contains a mixture of small copper spheres and small lead spheres. The total volume of both metals is measured by the displacement of water to be 420 cm$^3$ and the total mass is 5.4 kg.What percentage of the spheres are copper?
but I can't get the right answer. I tried to do this:
Given:
mtotal= 5.4kg--... |
I have to do research on a drug called Amifostine 2-(3-aminopropylamino)ethylsulfanyl
phosphonic acid. ![enter image description here][1]
I'm supposed to say how the organic reaction works inside the body. I understand that it becomes hydrolysed by an enzyme become the active form; 2-((aminopropyl)amino)ethanethio... |
A box contains a mixture of small copper spheres and small lead spheres. The total volume of both metals is measured by the displacement of water to be 420 cm³ and the total mass is 5.4 kg. What percentage of the spheres are copper?
but I can't get the right answer. I tried to do this:
Given:
$m_{total} = 5.... |
I want to extract the $KI$ component of the Lugol solution, is there a method to do it? If not, how can I make a $KI$ solution? |
Can we extract $KI$ from Lugol solution? |
I am currently studying stoichiometry (high school level) and we came across the following equation in school:
2 H2 + 1 O2 = 2 H2O
which is clear to me. We learned in school that reactions in chemistry only happen if there are enough atoms/molecules to react (so every molecule/atom can react), therefore the follo... |
Can 1 mole of H2 react partially with one mole of O2? |
I am currently studying stoichiometry (high school level) and we came across the following equation in school:
$$
2\ H_2 + 1\ O_2 = 2\ H_2O
$$
which is clear to me. We learned in school that reactions in chemistry only happen if there are enough atoms/molecules to react (so every molecule/atom can react), the... |
I am currently studying stoichiometry (high school level) and we came across the following equation in school:
$\ce{2H2 + 1O2 -> 2H2O}$
which is clear to me. We learned in school that reactions in chemistry only happen if there are enough atoms/molecules to react (so every molecule/atom can react), therefore ... |
Can 1 mole of $\ce{H2}$ react partially with one mole of $\ce{O2}$? |
I am currently studying stoichiometry (high school level) and we came across the following equation in school:
$\ce{2H2 + 1O2 -> 2H2O}$
which is clear to me. We learned in school that reactions in chemistry only happen if there are enough atoms/molecules to react (so every molecule/atom can react), therefore ... |
Can 1 mole of H2 react partially with one mole of O2? |
I am currently studying stoichiometry (high school level) and we came across the following equation in school:
$\ce{2H2 + 1O2 -> 2H2O}$
which is clear to me. We learned in school that reactions in chemistry only happen if there are enough atoms/molecules to react (so every molecule/atom can react), therefore ... |
Does Zinc become black & dull after reacting with dil. HCl? |
In the reaction where $\ce{Zn}$ reacts with $\ce{HCl}$ to give off Hydrogen gas & Zinc Chloride solution, does the zinc turn a dull black color after a while? If so, why? |
I am advising a student on her senior math thesis. She would like to involve chemistry somehow (her other major). I know no chemistry. I have read in several places that representation theory features prominently in some areas of chemistry. When I try to read anything online I am not sure how much chemistry one nee... |
I am advising a student on her senior math thesis. She would like to involve chemistry somehow (her other major). I know no chemistry. I have read in several places that representation theory features prominently in some areas of chemistry. When I try to read anything online I am not sure how much chemistry one nee... |
Here are some **standard electrode potentials**:-
$$SO_4^{2-} + 4H^+ +2e^-\rightarrow SO_2 +2H_2O\\E^o=0.17V\\
NO_3^-+4H^++3e^-\rightarrow NO+2H_2O\\E^o=0.97V\\
NO_3^-+2H^++e^-\rightarrow NO_2+H_2O\\E^o=0.78V$$
When nitric acid reacts with a metal, either nitrogen dioxide or Nitric oxide is formed? How do yo... |
There are elements like Neptunium and Plutonium in the periodic table..Did their discovery have anything to do with Neptune and Pluto? or Are they randomly assigned with such names? |
Does an name of an element has anything to do with Planets? |
For a chemistry lab, I'm required to calculate the vapor pressure of some organic solvents... methanol, ethanol, and propanol, in addition to an "unknown" sample of some solvent. In the lab, we were instructed to heat these solvents in a sealed syringe along with 5 mL of air. While they were being heated, I recorded th... |
More than dozen of heavy elements of periodic table do not occur naturally but are prepared artificially at nuclear reactors.. These elements are said to disappear in a flash..
So, why invest lot of money for the discovery of such elements? What are the advantages of such elements which disappear in a flash? |
What is advantage of creating elements that disappear in a flash? |
There are elements like Neptunium and Plutonium in the periodic table. Did their discovery have anything to do with Neptune and Pluto? Or are they randomly assigned with such names? |
Which silver halide is the most soluble? |
Do the names of some elements have anything to do with Planets? |
Asked and answered, but this is a good place to include other astronomically named elements:
- **[cerium](http://elements.vanderkrogt.net/element.php?sym=Ce)** named after the asteroid Ceres (or the Roman goddess of agriculture)
- **[helium](http://elements.vanderkrogt.net/element.php?sym=He)** from the Greek *he... |
For a reaction,
$$aA+bB \rightarrow cC+dD$$
The equilibrium constant is
$$k_c=\frac{[C]^c[D]^d}{[A]^a[B]^b}$$
Regardless of the mechanism of the reaction. Why is this the case? |
How is it that the equilibrium constant does not depend on mechanism? |
For a reaction,
$$aA+bB \rightarrow cC+dD$$
The equilibrium constant is
$$k_c=\frac{[C]^c[D]^d}{[A]^a[B]^b}$$
Regardless of the mechanism of the reaction. Why is this the case?
EDIT: I've seen derivations that use a reaction in one elementary step to demonstrate this, but this obviously doesn't work in general.... |
Why sigma bonds are stronger than pi bonds.? |
Why sigma bonds are stonger than pi bonds.? |
Why are sigma bonds stronger than pi bonds? |
Why are sigma bonds stronger than pi bonds? |
I read that:-
> Take a cupful of water in a beaker and add a few drops of dilute
> sulphuric acid. Heat the water. When it starts boiling add copper
> sulphate powder slowly while stirring continuously.
> Continue adding copper sulphate powder till no more powder can be
> dissolved. Filter the solution. Allow it... |
I am new to this page, so please correct me if I am posting my question in the wrong forum.
I have been looking for a physical explanation for entropy and enthalpy variations. An example would be the air system of the vehicle, where always people say we have a strong enthalpy and entropy variations along the exhaust l... |
Enthalpy ...When and how does it varry? |
I am trying to compute the ionization energy of H2+ molecule ion from the electronic energy spectrum. The question is whether one should use the purely electronic Hamiltonian or the Hamiltonian with the internuclear repulsion term to do that? I illustrated two ways to compute the ionization energy below. Which one is c... |
Here are some **standard electrode potentials**:-
$$SO_4^{2-} + 4H^+ +2e^-\rightarrow SO_2 +2H_2O\\E^o=0.17V\\
NO_3^-+4H^++3e^-\rightarrow NO+2H_2O\\E^o=0.97V\\
NO_3^-+2H^++e^-\rightarrow NO_2+H_2O\\E^o=0.78V$$
When nitric acid reacts with a metal, either nitrogen dioxide or Nitric oxide is formed? How do yo... |
I have been looking for a physical explanation for entropy and enthalpy variations. An example would be the air system of a vehicle, where people say we have a strong enthalpy and entropy variations along the exhaust line, which is not the case in the fresh air line. How could that be possible? |
Enthalpy: when and how does it vary? |
Here are some **standard electrode potentials**:-
$$SO_4^{2-} + 4H^+ +2e^-\rightarrow SO_2 +2H_2O\\E^o=0.17V\\
NO_3^-+4H^++3e^-\rightarrow NO+2H_2O\\E^o=0.97V\\
NO_3^-+2H^++e^-\rightarrow NO_2+H_2O\\E^o=0.78V$$
When nitric acid reacts with a metal, either $NO_2$ or $NO$ is formed? How do you **predict which ... |
NUCLEAR FUSION REACTIONS VIOLATE LAW OF CONSERVATION OF MASS,BUT IT HAS NOT YET BEEN TAKEN INTO ACCOUNT.WHY? |
Nuclear fusion reactions violate law of conservation of mass, but it has not yet been taken into account. Why? |
I am trying to compute the ionization energy of $\ce{H}^{2+}$ molecule ion from the electronic energy spectrum. The question is whether one should use the purely electronic Hamiltonian or the Hamiltonian with the internuclear repulsion term to do that? I illustrated two ways to compute the ionization energy below. Whic... |
I am trying to compute the ionization energy of $H_2^+$ molecule ion from the electronic energy spectrum. The question is whether one should use the purely electronic Hamiltonian or the Hamiltonian with the internuclear repulsion term to do that? I illustrated two ways to compute the ionization energy below. Which one ... |
Imagine a container of fixed volume is taken and hydrogen gas is filled in it, as a result the container floats in air. But if in the same container is filled with so much hydrogen that the hydrogen gas molecules had to compress to fit in the container, will the container still float in air ? |
Will compressed hydrogen float in air? |
Here is a short answer to your question!
The compression will result in increament of density of hydrogen in the container.
Hydrogen will float in the air until its density becomes equal to air through the compression.
Hydrogen's density (0.08988 g/L) is **very much less** than that of air's (1.225 kg/m3).
... |
Here is a short answer to your question!
The compression will result in increament of density of hydrogen in the container.
Hydrogen will float in the air until its density becomes equal to air through the compression.
Hydrogen's density (0.08988 g/L) is **very much less** than that of air's (1.225 kg/m3).
As ... |
Yes. A simple example is an ordinary balloon, which places the gas inside it under pressure (because the tension of the rubber surface adds to the air pressure from outside the balloon), yet the balloon still floats readily.
What you're probably talking about is a theoretical container that can hold highly-compresse... |
Yes. A simple example is an ordinary balloon, which places the gas inside it under pressure (because the tension of the rubber surface adds to the air pressure from outside the balloon), yet the balloon still floats readily.
What you're probably talking about is a theoretical container that can hold highly-compresse... |
Yes. A simple example is an ordinary balloon, which places the gas inside it under pressure (because the tension of the rubber surface adds to the air pressure from outside the balloon), yet the balloon still floats readily.
What you're probably talking about is a theoretical container that can hold highly-compresse... |
Are there any theories about "the first life" i mean the how the first amino acid appeared on earth? |
Is there a prove or a theory that the first amino acid synthesis was influenced by a change in heat, gravitation, radiation or something like that? |
How did the first amino acids appear on earth? |
Pectin is an example of a food safe polyelectrolyte. It acts as an acid because it is a proton donor and develops negative charges along the polymer.
Can you think of any examples of food safe polyelectrolytes that act as bases and develop positive charges along the polymer? |
Food safe basic polyelectrolytes? |
The process of racemization of an optically compound is entropy driven and hence nature prefers a racemic mixture to an optically active one, which is consistent with the idea of the intuitive understanding of entropy as the degree of randomness or disorder. Then, how can the entropy change of a process of conversion o... |
Why does having molecular chirality result in optical rotation? The dissymetry or chirality of molecules translates to the rotation of plane polarized light, the magnitude and direction depending on the concentration and the nature of the substance. But why does molecular chirality cause the rotation of plane polarized... |
why nature choose thermodynamically stable complexes? |
With regards to complexes, I read that thermodynamic products are favored over kinetic products, which are labile. Why wouldn't the first product formed be the most prominent?
|
I used to be under the (wrong) assumption that the density of an element correlates with it's atomic number, since (I thought) having more neutrons meant the atom weighed more. But of course that's wrong.
So why does make osmium with an atomic number of 76 more dense than say uranium with an atomic number of 92? |
What dictates the density of an element? |
I used to be under the (wrong) assumption that the density of an element correlates with it's atomic number $\mathrm{Z}$, I thought that since having more neutrons meant the atom weighed more; but of course that's wrong.
So why does make osmium $\mathrm{Os}$, with an atomic number of $\mathrm{Z}_{\mathrm{Os}}=76$ m... |
What determines the density of an element? |
I used to be under the (wrong) assumption that the density of an element correlates with it's atomic number $\mathrm{Z}$, I thought that since having more protons meant the atom weighed more; but of course that's wrong.
So why does make osmium $\mathrm{Os}$, with an atomic number of $\mathrm{Z}_{\mathrm{Os}}=76$ mo... |
Asked and answered, but this is a good place to include other astronomically named elements:
- **[cerium](http://elements.vanderkrogt.net/element.php?sym=Ce)** named after the asteroid Ceres (or the Roman goddess of agriculture)
- **[helium](http://elements.vanderkrogt.net/element.php?sym=He)** from the Greek *he... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.