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I'm asking this because I found a [link](http://www.sigmaaldrich.com/life-science/core-bioreagents/biological-buffers/learning-center/buffer-reference-center.html) for imidazole-HCl buffer: , but from what I understand, a buffer is a weak acid or base with its corresponding salt. Would imidazole-HCl buffer be a salt so... |
Where can I obtain research material on the synthesis of polypyrrole? |
>A tangent drawn on "conc. of product vs. time" curve of a 1st order reaction makes an angle 30 degrees with the y-axis at 20min. Find the rate after 20mins
I first tried to find the equation like this:
$$k=\frac{2.303}{t}log\frac{a}{a-x}$$
Let k/2.303 be c. Here, 'a' is the initial concentration of reactant.
$$... |
Why don't periodic acids convert alkenes to 1,2 diols? |
It would be useful to be able to predict relative evaporation rates of liquids. For small reduced temperatures the heat of vaporization is relatively constant, but it is not one of the more common properties cited for substances.
Is there any sort of functional relationship between enthalpy of vaporization and comm... |
Is there a relationship between viscosity and enthalpy of vaporization? |
I have two volatile compounds (such as ethyl acetate and ethyl propionate). I am going to separate these compounds by simple and fractional distillation.
How do I calculate mole ratios of the two compounds and determine the boiling point temperatures of the first drop based on the liquid and vapor phase diagram?
|
How to calculate mole ratio of two volatile compounds in distillation? |
I was under the impression that chemistry almost exclusively involves valence electrons because there isn't enough energy to strip off electrons further in. If that is true, and atoms in the same line behave similarly because of the same number of valence electrons, then why is SiO2 a solid while CO2 is a gas? Surely ... |
Why is SiO2 solid while CO2 is a gas? |
I was under the impression that chemistry almost exclusively involves valence electrons because there isn't enough energy to strip off electrons located closer to the nucleus.
If that is true, and elements in the same period have similar properties because they have the same number of valence electrons, then why is... |
Found a question asking the above which states the answer than Sulphur has lesser second EA than Oxygen. But as we see in Sulphur the inter-electronic repulsion is lesser shouldn't it be willing to take up another electron more easily than oxygen uninegative ion ? |
Who has a greater second electron affinity among Sulphur & Oxygen? |
I am an electric engineer, and I read about battery self discharge phenomenon. I was wondering whether a battery self discharge rate is the same when it is unconnected (i.e. in storage) and connected (i.e. when it is plugged into a device and being discharged "normally").
In other words, when I calculate battery life ... |
I am an electric engineer, and I read about battery self discharge phenomenon. I was wondering whether a battery self discharge rate is the same when it is unconnected (i.e. in storage) and connected (i.e. when it is plugged into a device and being discharged "normally").
In other words, when I calculate battery lif... |
Does battery self discharge when connected? |
Would solutions count as an answer? I think picric acid (2,4,6-trinitrophenol) has been used as an etchant in the past. I suspect there are less explosive variants now. |
> A tangent drawn on “conc. of product vs. time” curve of a 1st order reaction makes an angle 30 degrees with the $y$-axis at 20 min. Find the rate after 20 min.
I first tried to find the equation like this:
$$k=\frac{2.303}{t}\log\frac{a}{a-x}$$
Let $k/2.303$ be $c$. Here, $a$ is the initial concentration of reac... |
According to Wikipedia, there are not many problems for which the Schrödinger equation can be solved analytically. [[1]] The $\ce{H2+}$ ion is probably the most complex molecule that can be treated this way.
As far as I know, every diatomic homonuclear system like this can be solved, e.g., $\ce{U2+}$.
Up to this ... |
I'm comparing a model with chemistry at equilibrium versus a kinetic chemistry.
I take a network of two reactions: methane steam reforming (MSR) and water gas shift (WGS) at 700°C.
I calculated extent of reaction of both reaction, with the equilibrium hypothesis, solving a system of two non-linear equation cont... |
First, one have to be really careful with the words. When it is said that the *Schrödinger equation* can be solved the dihydrogen cation completely *analytically*, several remarks has to be made.
- There few different Schrödinger equations out there, so it is better to explicitly mention that one which can be solve... |
> A tangent drawn on “conc. of product vs. time” curve of a 1st order reaction makes an angle 30 degrees with the $y$-axis at 20 min. Find the rate after 20 min.
I first tried to find the equation like this:
$$k=\frac{2.303}{t}\log\frac{a}{a-x}$$
Let $\frac{k}{2.303}$ be $c$ to make calculations less messy. Here, ... |
First, one have to be really careful with the words. When it is said that the *Schrödinger equation* can be solved the dihydrogen cation completely *analytically*, several remarks has to be made.
- There are few different Schrödinger equations out there, so it is better to explicitly mention that one which can be s... |
First, one has to be really careful with the words: when it is said that the *Schrödinger equation* can be solved the dihydrogen cation completely *analytically*, several remarks has to be made.
- There are few different Schrödinger equations out there, so it is better to explicitly mention that one which can be so... |
[![chlorine_trifluoride][1]][1]
Why is the first structure more stable than the second ?
In the first one the angle between the two pair of nonbonding electrons is about 120° which is a lot less than that in the second structure. And it is also very well known that **lone** **pair**-**lone** **pair repulsions**... |
> A tangent drawn on “conc. of product vs. time” curve of a 1st order reaction makes an angle 30 degrees with the $y$-axis at 20 min. Find the rate after 20 min.
I first tried to find the equation like this:
$$k=\frac{2.303}{t}\log\frac{a}{a-x}$$
Let $\frac{k}{2.303}$ be $c$ to make calculations less messy. Here, ... |
[![enter image description here][1]][1]
[![enter image description here][2]][2]
Why is the first structure with $\ce{A=Cl}$ and $\ce{X=F}$ more stable than the second one?
In the first one the angle between the two pair of nonbonding electrons is about 120° which is a lot less than that in the second structure.... |
Is there any gas that contains oxygen in itself so that it doesn't require oxygen from environment for burning?
What I'm actually trying to achieve is to use LPG gas and attach a burner to it through a pipe and then put the burner in an environment that has no air, somewhat like vacuum. Is there still any way to lit... |
[![enter image description here][1]][1]
[![enter image description here][2]][2]
Why is the first structure with $\ce{A=Cl}$ and $\ce{X=F}$ more stable than the second one?
In the first one the angle between the two pair of nonbonding electrons is about 120° which is a lot less than that in the second structure.... |
I have been trying for a while to determine what products are produced when copper sulfate reacts with sodium bicarbonate at room temperature and standard pressure. However, while I was looking, I found conflicting information concerning what products are formed. Some sources claim that the products are copper hydroxid... |
What are the products of a reaction between copper sulfate and sodium bicarbonate? |
I found a question asking the above which states that sulfur has a lesser second electron affinity than oxygen. But since the inter-electronic repulsion in sulfur is lesser, shouldn't it be willing to take up another electron more easily than an oxygen ion with a -1 charge? |
Which element has a greater second electron affinity, sulfur or oxygen? |
I am confused about a specific part of Le Chatelier's Principle. My questions revolves around a homework assignment question:
2SO2(g) + O2(g) ⇌ 2SO3(g) ΔH⁰ = –198.2 kJ/mol
Comment on the changes in the concentrations of SO2, O2, and SO3 at equilibrium if we were to increase the temperature of the system.
... |
Le Chatelier's Principle: What does temperature do to gas concentrations? |
I am confused about a specific part of Le Chatelier's Principle. My question revolves around a homework assignment question:
2SO2(g) + O2(g) ⇌ 2SO3(g) ΔH⁰ = –198.2 kJ/mol
Comment on the changes in the concentrations of SO2, O2, and SO3 at equilibrium if we were to increase the temperature of the system.
... |
I am confused about a specific part of Le Chatelier's Principle. My questions revolve around a homework assignment question:
> $$\ce{2SO2(g) + O2(g) ⇌ 2SO3(g)} \qquad\mathrm{ΔH⁰ = –198.2 \frac{kJ}{mol}}$$
> Comment on the changes in the concentrations of $\ce{SO2}$, $\ce{O2}$, and $\ce{SO3}$ at equilibrium if w... |
In $\ce{ClF3}$ the central chlorine atom is roughly $\ce{sp^2}$ hybridized. This means that we will have 3 $\ce{sp^2}$ orbitals emanating from the chlorine; they will form an equatorial plane and will either contain a lone pair of electrons or bond to a ligand. Further in the case of $\ce{sp^2}$ hybridization, we al... |
[![enter image description here][1]][1]
[![enter image description here][2]][2]
Why is the first structure on the left with $\ce{A=Cl}$ and $\ce{X=F}$ more stable than the second one on the right?
In the first one the angle between the two pair of nonbonding electrons is about 120° which is a lot less than that... |
[![enter image description here][1]][1]
Why is the first structure on the left more stable than the second one on the right?
In the first one the angle between the two pair of nonbonding electrons is about 120° which is a lot less than that in the second structure. And it is also very well known that **lone** **p... |
I am confused about a specific part of Le Chatelier's Principle. My question revolves around a homework assignment question:
> $$\ce{2SO2(g) + O2(g) ⇌ 2SO3(g)} \qquad\mathrm{ΔH⁰ = –198.2 \frac{kJ}{mol}}$$
> Comment on the changes in the concentrations of $\ce{SO2}$, $\ce{O2}$, and $\ce{SO3}$ at equilibrium if w... |
Le Chatelier's Principle: What does temperature do gas concentrations? |
**Short Answer**
The structure on the left is "preferred" because the structure on the right cannot exist. You cannot put 4 electrons in a p-orbital.
**Detailed Explanation**
In $\ce{ClF3}$ the central chlorine atom is roughly $\ce{sp^2}$ hybridized. This means that we will have 3 $\ce{sp^2}$ orbitals emanat... |
I am confused about a specific part of Le Chatelier's Principle. My question revolves around a homework assignment question:
> $$\ce{2SO2(g) + O2(g) <=> 2SO3(g)} \qquad\Delta H^\circ = -198.2\:\mathrm{\frac{kJ}{mol}}$$
> Comment on the changes in the concentrations of $\ce{SO2}$, $\ce{O2}$, and $\ce{SO3}$ at eq... |
Is there any gas that contains oxygen so that it doesn't require oxygen from the environment in order to burn?
What I am trying to do is use LPG gas, which is fed through a pipe to a burner that is placed in an environment that has no air, somewhat like a vacuum. Is there any way to light the burner inside that vacu... |
How can I light a fire in this case? |
I completely agree with Wildcat's answer. Excellent stuff. This part, though, got me thinking:
> Anyway, values of the ionic radii are based on crystallographic data, but what is actually determined in X-ray crystallography is the distance between two ions, not their radii. Then it is basically up to you how to di... |
If you have some sort of sports drink that contains sucrose, how would you take that sucrose and break it down into its components, glucose and fructose? I know that sucrose + water will break it apart, but how can it still remain together (as sucrose) while in the bottle of sports drink?
I'm trying to compare the l... |
If you have some sort of sports drink that contains sucrose, how would you take that sucrose and break it down into its components, glucose and fructose? I know that sucrose + water will break it apart, but how can it still remain together (as sucrose) while in the bottle of sports drink?
I am trying to compare the ... |
Why is microcosmic salt called so? |
I am trying to calculate molar volume of certain crystal lattices to be used for crystal growth kinetics calculations. The information I have is the crystal volume & crystal lattices. For example the crystal $\ce{Cu41Sn11}$ has the structure cF416 and the information taken from a certain crystal database is as follows:... |
i'm an engineering student preparing for my graduation, in one step of my graduation project i used a rechargeable battery(1.2 volt) , i was shocked when this battery is starting to recharge it self until it reach 1.04 volt ( not fully ) for many many cycles and immediately when the voltmeter reads 0 volt from it , whe... |
How could a rechargeable battery recharge itself? |
I'm an engineering student preparing for my graduation, in one step of my graduation project I used a rechargeable battery(1.2 volt), i was shocked when this battery is starting to recharge it self until it reach 1.04 volt (not fully) for many many cycles and immediately when the voltmeter reads 0 volt from it, when i ... |
Most of the common organic solvents are regarded as noncorrosive, but stainless steel can be attacked by formic, acetic, and propanoic acids.
[Corrosion of stainless steel by organic solvent mixtures, Alice Y. Ku , David H. Freeman, Anal. Chem., 1977, 49 (11), pp 1637–1638
DOI: 10.1021/ac50019a044][1]
Are ther... |
Find the average life of a radio nuclide which decays by parallel paths
$$A\rightarrow B$$
$$2A\rightarrow B$$
Where decay constant for first reaction is $\lambda_1=0.018$ and $\lambda_2=0.001$ per second.
Attempt:
I used the formula $$\frac{1}{t}=\frac{t_1t_2}{t_1+t_2}$$ where $t$ represents the mean life. Th... |
I have a sort of high-level question about the theoretical modeling of photocatalysis. Most of the computational work on photocatalysis involves DFT calculations looking at bandgaps, free energy profiles and reaction pathways. I have also seen a handful of papers that use reactive MD to probe how the surrounding water ... |
Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment.
Why are some compounds hygroscopic and others not? What about their structures allows them to hold water? The atoms in them/ a certain bond/ ctructure?
How do you know when a compund is more hygroscopi... |
What is the cause of hygroscopy? By molecular formula/structure? |
Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment.
Why are some compounds hygroscopic and others not? What about their structures allows them to hold water? The atoms in them/ a certain bond/ ctructure?
How do you know when a compund is more hygroscopi... |
How does the following work in Alkyne? |
Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment.
Why are some compounds hygroscopic and others are not? What is it about their structures that allows them to hold water? Is it due to the atoms being arranged in a certain structure due to bonding?
How ... |
What is the cause of hygroscopy? |
I have a sort of high-level question about the theoretical modeling of photocatalysis. Most of the computational work on photocatalysis involves DFT calculations looking at band gaps, free energy profiles, and reaction pathways. I have also seen a handful of papers that use reactive MD to probe how the surrounding wate... |
Do aromatic dienes undergo Diels Alder reaction? My understanding was that the pi bonds in aromatic compounds, are not as localised as in other compunds, like aliphatic dienes. So, the dienophile shouldn't be as willing to go to these compounds. Am I correct? |
Do aromatic dienes undergo Diels Alder reaction? |
Do aromatic dienes undergo Diels Alder reactions?
My understanding is that the $\pi$ bonds in aromatic compounds are not as localised as they are in other compounds, such as aliphatic dienes. Therefore, the dienophile shouldn't be as willing to go to these compounds. Am I correct? |
$$\ce{H2O~(l) + NaCl~(s) ->[\Delta] Na+~(aq) + Cl^{-}~(aq)}$$
When table salt is placed in water, it dissolves due to the polarity of water molecules. When solvation takes place, negatively polar sides of water molecules attach to $\ce{Na+}$ ions, and positively polar sides of water molecules attach to $\ce{Cl-}$ io... |
Do aromatic dienes undergo Diels-Alder reactions?
My understanding is that the $\pi$ bonds in aromatic compounds are not as localised as they are in other compounds, such as aliphatic dienes. Therefore, the dienophile shouldn't be as willing to go to these compounds. Am I correct? |
Do aromatic dienes undergo the Diels-Alder reaction? |
I have two identical graphite strips of dimensions 3.5 cm by 1 cm. Both are 3/4 submerged in aqueous $\ce{NaCl}$ solution (0.34 mol/dm$^3$, 2% wt) separated by a distance of 7 cm. I have attached crocodile clips to each strip and a voltmeter is used to record the potential difference between the two graphite strips.
... |
How do delocalized electrons hold metal atoms together? What are the forces of attraction between the atoms and the electrons called? |
How does a "sea of electrons" hold metal atom together? |
As a computational materials chemist studying photocatalysis, how close to realistic systems can your modeling get?
I have a sort of high-level question about the theoretical modeling of photocatalysis. Most of the computational work on photocatalysis involves DFT calculations looking at band gaps, free energy prof... |
1. Let the reactant be $S$ and the product be $P$. Let $p$ be the dimenionless product concentration, $\frac{P}{S_0}$. First order kinetics:
$$\frac{P}{S_0} = p = 1- e^{-k t}$$
2. Slope of first-order kinetics:
$$\frac{dp}{dt} = k e ^{-kt}$$
3. Slopes and angles. One confusing thing about this problem is... |
1. Let the reactant be $S$ and the product be $P$. Let $p$ be the dimenionless product concentration, $\frac{P}{S_0}$. First order kinetics:
$$\frac{P}{S_0} = p = 1- e^{-k t}$$
2. Slope of first-order kinetics:
$$\frac{dp}{dt} = k e ^{-kt}$$
3. Slopes and angles. One confusing thing about this problem is... |
I mean by "combining" is to make a new half-reaction equation and not an overall equation for a reaction in while.
For instance, I was trying to arrive at the following half-reaction:
$\ce{MnO2(s) + 4H+(aq) + 2e- -> Mn^{2+}(aq) + 2H2O(l)}\quad E^\circ= 1.23\,\mathrm{V}$
by combining
$\ce{MnO4^{-}(aq) + 8H^+... |
Why can some redox half-reactions be combined and some cannot? |
I mean by "combining" is to make a new half-reaction equation and not an overall equation for a reaction in whole.
For instance, I was trying to arrive at the following half-reaction:
$\ce{MnO2(s) + 4H+(aq) + 2e- -> Mn^{2+}(aq) + 2H2O(l)}\quad E^\circ= 1.23\,\mathrm{V}$
by combining
$\ce{MnO4^{-}(aq) + 8H^+... |
Yes. See [this video for a demonstration](https://www.youtube.com/watch?v=LaaORZ0ofCY). You'll get $\ce{AlCl3}(aq)$ and $\ce{H2}(g)$ as products. You can capture the hydrogen and proceed with your experiments. |
Yes. See [this video for a demonstration](https://www.youtube.com/watch?v=LaaORZ0ofCY).
The [reaction is](https://en.wikipedia.org/wiki/Aluminium_chloride):
$$\ce{ 2Al (s) + 6 HCl (aq) -> 2AlCl3 (s) + 3H2(g)}$$
You can capture the hydrogen and proceed with your experiments. |
I am researching this reaction for my Chemistry assessment, and various sources I have dug up state different answers and opinions on what the products are and what the stochiometry is, sometimes giving no answer at all. In one source, sulfuric acid is a catalyst that speeds up the reaction while in another source, sul... |
What is the stochiometric equation of the sucrose and potassium chlorate reaction with sulfuric acid? |
I am currently conducting an experiment into the glucose content of certain sports drinks. However, I have hit a roadblock. A majority of the drinks that I intend to test contain sucrose. I am thinking that by adding 1.0M HCl, to say, 100mL of solution(sports drink), it will decompose the sucrose into its constituents.... |
How Many mL of 1.0M HCl Would be Required to Completely Decompose Sucrose into Glucose and Fructose? |
I am currently conducting an experiment into the glucose content of certain sports drinks. However, I have hit a roadblock. A majority of the drinks that I intend to test contain sucrose. I am thinking that by adding 1.0M HCl, to say, 100mL of solution(sports drink), it will decompose the sucrose into its constituents.... |
I am currently conducting an experiment into the glucose content of certain sports drinks. However, I have hit a roadblock. A majority of the drinks that I intend to test contain sucrose. I am thinking that by adding $\mathrm{1.0M~HCl}$, to say, $\mathrm{100~mL}$ of solution (sports drink), it will decompose the sucros... |
What is the input impedance of your voltmeter? How much DC current does it pass to measure a potential?
In theory, the input impedance is infinite and the DC current is zero, but in practice, this isn't the case.
In the NaCl solution with graphite electrodes, any DC current has to pass through electrolysis or imp... |
I am currently conducting an experiment into the glucose content of certain sports drinks. However, I have hit a roadblock. A majority of the drinks that I intend to test contain sucrose. I am thinking that by adding $\mathrm{1.0M~HCl}$, to say, $\mathrm{100~mL}$ of solution (sports drink), it will decompose the sucros... |
I am researching this reaction for my chemistry assessment. Various sources I have dug up state different answers and opinions on what the stoichiometry is and what the products are, sometimes giving no answer at all.
In one source, sulfuric acid is a catalyst that speeds up the reaction while in another source, su... |
My teacher likes to use household materials to do experiments. Today, we did an experiment that showed the reaction of vinegar and eggshell.
When we were doing the analysis of the experiment, I realized that my teacher used the term acetic acid ($\ce{CH3COOH}$) instead of ethanoic acid. So, my questions are:
1)... |
When you calculate the solubility product constant for a salt and one of its hydrates, you sometimes get drastically different numbers! I don't know how this can be because they both dissociate into the same ions. For example, sodium sulfate heptahydrate $\ce{Na2SO4.(H2O)7}$ is more soluble than anhydrous sodium sulfat... |
How are solubilities of hydrate salts determined when competing equilibria are unavoidable? |
How was the ASTM formula for Viscosity Index derived?
Specifically with reference to the reference oils considered and the table for it.
The viscosity index can be calculated using the following formula:
V = 100*(L-U)/(L-H)
Check this reference for details:
http://www.ptplab.net/upfile/201402/17/112156706.pd... |
How is the ASTM formula used to produce the Viscosity Index derived?
My question is specifically about the reference oils considered and the table for it.
The viscosity index can be calculated using the following formula:
$$V = 100*(L-U)/(L-H)$$
Check this reference for details:
http://www.ptplab.net/upfile/... |
How was the ASTM formula for Viscosity Index derived?
Specifically with reference to the reference oils considered and the table for it.
The viscosity index can be calculated using the following formula:
$$V = \frac{100*(L-U)}{(L-H)}$$
Check [this reference](http://www.ptplab.net/upfile/201402/17/112156706.pd... |
How is this hydride shift reaction type called?
[![enter image description here][1]][1]
I think it's not one of following types:
- cycloaddition (Diels Alder)
- electrocyclic ring opening
- sigmatropic rearrangement
- ene reaction
- cheleotropic reaction
Therefore I'm thinking what else can been th... |
The textbooks starts with the phenomena that double helix is an expression of the rules of chemistry.
> Hydrogen bonds are important in determining the formation of **specific**
base pairs in the double helix. However in single staranded DNA, the hydrogen bond donors and acceptors are exposed to solution and can ... |
Why is the formation of double helix between non complementary sequences disfavoured? |
The claim that "the tars in cannabis are considerably more dangerous than those in tobacco" is made in Patricks An Introduction to Medicinal Chemistry (4th edition, p. 169). It's just a simple one line statement and not much attention is given to it, but from what I already knew this is to say the least a very controve... |
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