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Are multiple transition states possible? Criteria to choose the correct one? |
I am studying a reaction using electronic structure methods using various software packages (ORCA,GAMESS, G09) and have found two possible transition structures between product and reactant. Both have imaginary frequencies, but each has a different energy value, frequencies and geometries. Some software coincide in the... |
I'm really tempted to post an answer, but I'd like to see your attempt first.
If you don't have any idea and [tag:inorganic-chemistry] is the right tag:
- Start with the hypothesis that your starting material is the salt of some metal.
- Some of the test are apparently useful to identify the cation, other... |
Please help me identify the following 5 substances; G, Y, T, L and J
G is a white solid which is insoluble in water. Consider the following reactions carried out on solid G.
Step 1
Excess dilute Nitric acid is added to a small amount of G in a test-tube. A colourless and odourless gas Y is given off and it is no... |
I am trying to make 5N HCl solution. SO far i understood that you need to get the molecular weight (36.5) and dibide i by the number of H that react in the acid-base reactions. The problem is that my HCL stoc is 37 %. how should i take this into account? |
I'm really tempted to post an answer, but I'd like to see your attempt first.
If you don't have any idea and [tag:inorganic-chemistry] is the right tag:
- Start with the hypothesis that your starting material is the salt of some metal.
- Some of the test are apparently useful to identify the cation, other... |
Pure oxygen does not burn. Oxygen is a _supporter_ of combustion, not a combustible material(fuel) itself.
Combustion reactions are as follows:
$$\text{combustible stuff} \ce{+ O2 -> } \text{various oxides} + heat$$
Note that nitrous oxide ($\ce{N2O}$) is also a supporter of combustion, which means that you ca... |
Pure oxygen does not burn. Oxygen is a _supporter_ of combustion, not a combustible material(fuel) itself.
Combustion reactions are as follows:
$$\text{combustible stuff} \ce{+ O2 -> } \text{various oxides} + \text{heat}$$
Note that nitrous oxide ($\ce{N2O}$) is also a supporter of combustion, which means that... |
Ever had a ballpoint pen that would all of a sudden hit a 'dead spot' on a sheet of paper and refuse to write? It's clearly not the pen, because when moved off to the corner it would draw perfect circles instantly. Move it back to the spot, and it stops working again. Usually I can get something blotchy if I write out ... |
What is going on when pen stops working on a section of paper? |
If in doubt, try it out.
I just spilled some olive oil on a sheet of paper and wiped it off again.
Result: The ballpoint pen does not write on the oily spot.
Did you *fat-finger* the paper? |
the specific heat capacity of liquid water is 4.18 J K^-1 g^-1. Calculate the energy required to heat 1.0 mol of water from 298K to 363K.
My question is: do I have to change the moles of water into grams or should I sub in 1.0 into the formula for specific heat capacity? |
Please help me identify the following 5 substances; G, Y, T, L and J
G is a white solid which is insoluble in water. Consider the following reactions carried out on solid G.
Step 1
Excess dilute Nitric acid is added to a small amount of G in a test-tube. A colourless and odourless gas Y is given off and it is no... |
As part of intern work I am running simulations on a group of compounds, but as it is I have little in the way of O-Chem experience and I wanted to be able to at least get some direction on naming these compounds (maybe some examples).
I think I've got the names of the functional groups down right, and I've recogni... |
If in doubt, try it out.
I just spilled some olive oil on a sheet of paper and wiped it off again.
Result: The ballpoint pen does not write on the oily spot.
Did you *fat-finger* the paper?
<hr>
**EDIT**
The experiment above confirmed the finding in the question but didn't give an explanation.
Act... |
I am trying to make 5N $\ce{HCl}$ solution. So far I understood that you need to get the molecular weight (36.5) and divide it by the number of $\ce{H+}$ that react in the acid-base reactions. The problem is that my $\ce{HCl}$ stock is 37 %. How should I take this into account? |
The specific heat capacity of liquid water is $4.18 \, \text{J} \, \text{K}^{-1} \, \text{g}^{-1}$. Calculate the energy required to heat $1.0 \, \text{mol}$ of water from $298 \, \text{K}$ to $363 \, \text{K}$.
My question is: Do I have to change the moles of water into grams or should I sub in $1.0$ into the formul... |
Please help me identify the following 5 substances; G, Y, T, L and J
G is a white solid which is insoluble in water. Consider the following reactions carried out on solid G.
**Step 1:**
Excess dilute Nitric acid is added to a small amount of G in a test-tube. A colourless and odourless gas Y is given off and i... |
According to ModernAtomicTheory :-
The ratio in which the different atoms combine may be fixed and integral but may not always be simple.
The example given is that in sugar molecule the ratio of C ,H and O atoms is 12:22:11 "which is not simple"
Well...what I see here us that 12,22,11 are whole numbers; then w... |
What is a simple ratio in which atoms combine? |
![enter image description here][1]
here is the data booklet we must refer too:
![enter image description here][2]
![enter image description here][3]
Here is the exam paper solution:
![enter image description here][4]
I dont understand how they conclude this.
1. Peak areas and the chemical sh... |
![enter image description here][1]
here is the data booklet we must refer too:
![enter image description here][2]
![enter image description here][3]
Here is the exam paper solution:
![enter image description here][4]
I dont understand how they conclude this.
1. Peak areas and the chemical sh... |
Here is the question and answer out of an exam paper:
![enter image description here][1]
[1]: https://i.stack.imgur.com/Afp3s.png
Firstly, I thought UV-Visible can also use radiation in the visible spectrum. Also when analysing sodium chloride (a molecule), then UV-Visible would be more appropriate than AA... |
Here is the question and answer out of an exam paper:
![enter image description here][1]
[1]: https://i.stack.imgur.com/Afp3s.png
Firstly, I thought UV-Visible can also use radiation in the visible spectrum. Also when analyzing sodium chloride (a molecule), then UV-Visible would be more appropriate than AA... |
I am doing a project in which I fill a cylinder with a volume of $636cm^2$ (made of stainless steel) with molten salt: 60% Sodium Nitrate ($NaNO_3$) and 40% Potassium Nitrate($KNO_3$).
The container might reach (worst case scenario) -35 degrees Celsius in a cold winter night and in the summer (with ideal conditions)... |
I am doing a project in which I fill a cylinder with a volume of $636cm^2$ (made of stainless steel) with molten salt: 60% Sodium Nitrate ($NaNO_3$) and 40% Potassium Nitrate($KNO_3$).
The container might reach (worst case scenario) -35 degrees Celsius in a cold winter night and in the summer (with ideal conditions)... |
##**Why is the smell of smoke so persistent, while many other strong smells are not?**
In fact this is a tricky question, because you can't make such a comparison. According to [IUPAC Gold book](http://goldbook.iupac.org/S05719.html) **Smoke** is:
> An aerosol originating from combustion, thermal decomposition or... |
I'm going to be using a finings agent with a possitive charge to remove negative trub from a solution (beer).
I would like to keep some chelated zinc in the solution - ideally zinc picolinate - so wondering what its' charge is? I'm hoping it's neutral...
Depending on the answer, are there any zinc chelates that c... |
Zinc Picolinate - Possitive, negative or neutral charge? |
I'm going to be using a finings agent with a positive charge to remove negative trub from a solution (beer).
I would like to keep some chelated zinc in the solution - ideally zinc picolinate - so wondering what its charge is? I'm hoping it's neutral...
Depending on the answer, are there any zinc chelates that car... |
Zinc Picolinate - Positive, negative or neutral charge? |
I found it quite hard to follow both the question and the answer, so I am going to state a few relevant things and paraphrase the answers of @LDC3 to add some clarity.
**Chemical shift (ppm) and peak area (integral)**
These are independent quantities. One tells you about the environment (shift) the protons are in... |
You have a standard pot of liquid electrolyte into which are dipped non-touching same-spaced paired strips of different clean metals. The external circuit between the strips is a sensitive voltmeter (with extremely high electrical resistance - hard by zero current flow). You measure the potential (noting direction!) ... |
An equation of heat is s * m * delta T. I know that delta T can be in either Celsius or Kelvin. However, one thing that confuses me is how the units cancel if delta T is in Celsius. How does this work? |
Thermochemistry Delta T? |
How do I prepare a 5N HCl solution? |
So, in mass spectrometry we have the following equation to describe a magnetic sector analyser,
$$\frac{m}{z}=\frac{B^2r^2e}{2V}.$$
Lets say that I have two particles with different mass/charge ratios,
$$\frac{m_1}{z_1} = 120.9,\quad \frac{m_2}{z_2} = 121.0,$$
and I have $B=2\text{T}$, $r=25\text{cm}$. For exampl... |
So, in mass spectrometry we have the following equation to describe a magnetic sector analyser,
$$\frac{m}{z}=\frac{B^2r^2e}{2V}.$$
Lets say that I have two particles with different mass/charge ratios,
$$\frac{m_1}{z_1} = 120.9,\quad \frac{m_2}{z_2} = 121.0,$$
and I have $B=2\text{T}$, $r=25\text{cm}$. For exampl... |
![enter image description here][1]
My working out:
Propan-1-ol : CH3CH2CH2OH
This can be broken up into:
- CH3 + CH2CH2OH
- CH3CH2 + CH2OH
- CH3CH2CH2 + OH
Base peak = most abundant fragment formed (highest peak)
How do i know which fragment is the "most abundant?"
After I know the fragment... |
How to calculate m/e value for the base peak in mass spectroscopy? |
Calculating molar conductance? |
Ok, so the following question is given in my text book.
>Of the molar conductance value of $Ca^{2+}$ and $Cl^-$ at infinite dilution are respectively $118.88\times10^{-4}$ and $77.33\times10^{-4}$ then that of $CaCl_2$ is (all have same unit)
So what I did was I added the molar conductivity of $Ca^{2+}$ and add... |
Yes, the process is correct, but do you understand why? |
I just read about <a href="http://en.wikipedia.org/wiki/Alchemy">Alchemy</a>. And it seems to me that many of their principles are closely <a href="http://en.wikipedia.org/wiki/Alchemy#Relation_to_the_science_of_chemistry">related</a> to chemistry.
So, here is my doubt - **Is it possible to make that alchemist stone... |
In what way does chemistry support the alchemist stone called Philosopher's Stone? |
In a <a href="http://en.wikipedia.org/wiki/Covalent_bond">covalent bond</a> between two <a href="http://en.wikipedia.org/wiki/Atoms">atoms</a>, an <a href="http://en.wikipedia.org/wiki/Electron">electron</a> from one of the either atom is shared by overlapping of their <a href="http://en.wikipedia.org/wiki/Atomic_orbit... |
Humic substance consists of many, to my knowledge poorly understood, species of organic matter, mostly carbohydrates chained in intersting (and also poorly understood) ways. Humic substance is an endproduct of digestion of other organic matter, and is in itself known to be hardly biodegradable. Industrial processes to ... |
How is Humic substance destroyed in nature? |
I just read about <a href="http://en.wikipedia.org/wiki/Alchemy">Alchemy</a>. And it seems to me that many of their principles are closely <a href="http://en.wikipedia.org/wiki/Alchemy#Relation_to_the_science_of_chemistry">related</a> to chemistry.
So, here is my doubt - **Is it possible to make that alchemist stone... |
I have a solution of water and oil mixed to as much as possible, since they won't actually mix. The supply is coming down a pipe at a relatively fast rate and I need to separate it so that the water goes down a pipe and the oil goes through another pipe.
How would this be done, without waiting days for it to occur?
... |
Oil-water separation is a big money industrial process, and there are a number of methods for successfully separating the two. So the answer to your question is best approached in two parts: a theoretical answer, and a practical answer.
Theoretically, yes. A number of systems exist and the best are described below. ... |
Oil-water separation is a big money industrial process, and there are a number of methods for successfully separating the two. So the answer to your question is best approached in two parts: a theoretical answer, and a practical answer.
Theoretically, yes. A number of systems exist and the best are described below. ... |
I have a pretty basic question but the last time I took Chemistry was in 2007. I am studying the Navy's Nuclear study guide for their interviews and one of the question I am faced with is below.
Determine the final pH and temperature when these two solutions are mixed together in a 3L container.
Sol A: 2L, pH = ... |
I working on the Navy study guide for their nuclear engineering programs and I am not a Chemist. Thus, I have come here to try and develop a better understanding of the subject matter. I am trying to answer the question below.
Why is pH important in materials selection?
I know it is a rather vague question, but... |
Metals are overall are attacked by acid, especially plus air. Aluminum and zinc are attacked by both acid and base. Cooling and heating water, and especially boiler water, must be delicately adjusted for pH and solutes to avoid chemical and galvanic corrosion of metal containment.
Seawater is nasty stuff. Seawater... |
The pH scale is merely a way of keeping track of the concentration a species (the hydrogen ion $\ce{H^+}$, $pH = -log\ a_{H^+} \simeq -log\ [H^+]$) in a medium (usually liquid, not necessarily aqueous). You can define arbitrary scales for other species, too. Analytical chemists are more familiar with scales such as p... |
The pH scale is merely a way of keeping track of the concentration a species (the hydrogen ion $\ce{H^+}$, $pH = -log\ a_{H^+} \simeq -log\ [H^+]$) in a medium (usually liquid, not necessarily aqueous). You can define arbitrary scales for other species, too. Analytical chemists are more familiar with scales such as p... |
The pH scale is merely a way of keeping track of the concentration a species (the hydrogen ion $\ce{H^+}$, $pH = -log\ a_{H^+} \simeq -log\ [H^+]$) in a medium (usually liquid, not necessarily aqueous). You can define arbitrary scales for other species, too. Analytical chemists are more familiar with scales such as p... |
![enter image description here][1]
![enter image description here][2]
The exam paper answer is 500, because we need the wavelength of "maximum absorbance." But this graph shows two curves, and the absorbance curve is omitted.
But what is the difference between an emission, absorbance, and an excitation spectr... |
According to Wikipedia, HF is miscible with water. But isn't hydrogen fluoride a gas at RT and a sensible pressure? What would happen if you just kept adding more HF gas to some water? |
HF and water miscible? |
I just read about <a href="http://en.wikipedia.org/wiki/Alchemy">Alchemy</a>. And it seems to me that many of their principles are closely <a href="http://en.wikipedia.org/wiki/Alchemy#Relation_to_the_science_of_chemistry">related</a> to chemistry.
So, here is my doubt - **How is it possible to make that alchemist s... |
What was the principle behind the Philosopher's Stone and how does modern chemistry support it? |
I am supposed to write the precipitation reaction for
$\ce{(NH4)2C2O4 + AgNO3 ->[\ce{H2O}]}$
Is my equation correct? I left out the Spector ions.
$$\ce{4(NH4) + 2 C2 +O4\rightarrow 4(NH4)2CO3}$$
[1]: https://i.stack.imgur.com/6SKUn.jpg |
I have a pretty basic question but the last time I took Chemistry was in 2007. I am studying the Navy's Nuclear study guide for their interviews and one of the question I am faced with is below.
Determine the final pH and temperature when these two solutions are mixed together in a 3L container.
Sol A: 2L, pH = ... |
I'm working on a high school chemistry book and want to double check one of the homework assignments. The question is for students to write the empirical and molecular formula for 1,2-dichloroethane.
I can't find this online. The molecular formula is given as C2H4Cl2, but could this also be the empirical formula? I d... |
I'm trying to do some quantum chemical calculations for the linear molecule FeP$_2$ in the gas phase as well as its crystal ([orthorhombic symmetry like here][1]). It seem that in both cases iron has an oxidation state of +6 and phosphorous -3. My questions are:
* are those oxidation states reasonable assumption for... |
>But isn't hydrogen fluoride a gas at RT and a sensible pressure?
Actually, it depends on the room in question. $HF$ boils at 19.5 C, meaning one can check if it mixes well with chill water or at relatively low pressure.
>What would happen if you just kept adding more $HF$ gas to some water?
Learn about bina... |
Admittedly it is vacuum phase, but are you certain about your oxidation state assignments? "nearly temperature independent susceptibility of -(8.8±0.7)centerdot10-6SI (at room temperature)"
doi:10.1016/j.jpcs.2013.04.015 <BR>
https://sciborg.uwaterloo.ca/~lfnazar/publications/Electrochem_Solid-State_Lett_6_8_A162-... |
I'm trying to do some quantum chemical calculations for the linear molecule FeP$_2$ in the gas phase as well as its crystal ([orthorhombic symmetry like here][1]). It seems that in both cases iron has an oxidation state of +6 and phosphorous -3. My questions are:
* are those oxidation states reasonable assumption fo... |
Here
oh = octahedral
td = tetrahedral
CN = co-ordination number
My problem is that, that why it is not possible to have a void with CN = 5 ?
My reasoning is:
According to the definition of CN i.e. the number of nearest neighbors of a particle (here a void ... |
Asked to write a balanced chemical equation for the reaction between sulfuric acid and sodium carbonate. The balanced equation isn't the problem. The question asks to also show all the state symbols.
All the equations I find online have sodium carbonate as a solution, not a solid. I'm also aware there are two forms o... |
Asked to write a balanced chemical equation for the reaction between sulfuric acid and sodium carbonate. The balanced equation isn't the problem. The question asks to also show all the state symbols.
All the equations I find online have sodium carbonate as a solution, not a solid. I'm also aware there are two forms o... |
I have a frequency calculation by Gaussian09. Now I would like to extract vibrational modes as a set of xyz coordinate files. I would like to manually recompute numerically the points along a transitional vector, since IRC calculations all fail. (I suspect it is no real saddle point, flat PES.)
There was/is a progra... |
I just read about <a href="http://en.wikipedia.org/wiki/Alchemy">Alchemy</a>. And it seems to me that many of their principles are closely <a href="http://en.wikipedia.org/wiki/Alchemy#Relation_to_the_science_of_chemistry">related</a> to chemistry.
So, here is my doubt - **Why is not possible to make that alchemist ... |
What was the misconception about the search of Philosopher's Stone and how does modern chemistry deals with this topic? |
I'm doing revision questions and want to double check something. The opening information reads:
Two chlorides of iron were prepared. One was prepared by reacting iron with dry chlorine
gas. 4.50 g of iron reacted with chlorine gas to produce 13.01 g of the chloride.
The other chloride was prepared by reacting iro... |
I'm doing revision questions and want to double check something. The opening information reads:
Two chlorides of iron were prepared. One was prepared by reacting iron with dry chlorine
gas. 4.50 g of iron reacted with chlorine gas to produce 13.01 g of the chloride.
The other chloride was prepared by reacting iro... |
> Two chlorides of iron were prepared.
I do **not** read that as: $\ce{FeCl_{n}}$ was prepared by two different methods, but as:
1. Reacting iron with dry chlorine gas yields $\ce{FeCl_{n}}$
2. Reacting iron with hydrogen chloride yields $\ce{FeCl_{m}}$
Apparently, iron is oxidized in both cases.
- W... |
Try to follow this reasoning. (mouse over for answer)
Which parameter is mandatory to determine if a substance precipitate or not?
>! solubility
How does this parameter behaves with sulphates?
>! many sulphate are soluble in water. Generally the sulphates become less soluble as you go down the group. So Sod... |
I fully understand and recognise the manner and which the series works.
I cannot find any references for the change in sigma donor capability moving up the series.
For example, comparing Cl- and NH3. Which of the two would be more a more willing sigma donor ?
Does this have something to do with how diffuse the... |
I have I microchannel test rig , I want to push a 150-300 ml/hr from water in my test , I would like to know which pump type i can use ? |
To model early fluid flow which types of pumps should be used? |
Can someone please tell me the chemical formula for just "Hypo"?
This question came up in previous exams and I don't know what is the general /chemical formula for just "Hypo". I can find the formula for hypo chlorite and hypo bromide, but I am unable to find formula for just " Hypo"
|
There are many foodstuffs that are ionically conductive (for example, anything moist and salty). What about foods that have a high electronic conductivity?
The only thing I can think of would be something which has been charred – presumably the char, being mostly carbon, would have a fairly high conductivity. |
Examples of electronically conductive foods? |
I have a frequency calculation by Gaussian09. Now I would like to extract vibrational modes as a set of xyz coordinate files. I would like to manually recompute numerically the points along a transitional vector, since IRC calculations all fail. (I suspect it is no real saddle point, flat PES.)
Consider the formatio... |
The definition:
The abbreviation m/z is used to denote the dimensionless quantity formed by dividing the mass number of an ion by its charge number. It has long been called the mass-to-charge ratio although m is not the ionic mass nor is z a multiple or the elementary (electronic) charge, e. The abbreviation m/e is,... |
We know that Gibbs free energy is same as negative of 8.314 times temperature in Kelvin times natural logarithm of equilibrium constant, or:
![Gibbs free energy][1]
Then, we also know Van't Hoff equation, like:
![Van't Hoff Equation][2]
(R in 8.314 J/mol K)
My question is: what kind of K we use for tho... |
What kind of equilibrium constant we use for Gibbs free energy and Van't Hoff equation? |
Many foods conduct electricity. The charge carriers are ions, and the conductivity is a function of temperature and ion mobility. Liquids, therefore, are generally better conductors. The electrical properties of foods are important parameters to consider in food processing operations such as ohmic heating, microwave he... |
If we have a long-chain hydrocarbon, such as decane, and we split it through thermal cracking (say in an industrial plant), we use high temperatures, and high pressures. Cracking produces smaller molecules - alkanes, and alkenes. It might look like this:
$$\ce{CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3}$$
Which is cr... |
Why are high pressures used in cracking of long-chain hydrocarbons? |
![enter image description here][1]
[1]: https://i.stack.imgur.com/5VMCy.jpg
What would be 'A' in the reaction (see image)? Any help would be deeply appreciated.
I know that Alc KOH does elimination but I was confused whether it would eliminate one bromine each from two rings and create a bond between both ... |
Product of Reaction? |
![enter image description here][1]
[1]: https://i.stack.imgur.com/5VMCy.jpg
What would be 'A' in the reaction (see image)? Any help would be deeply appreciated.
I know that Alc KOH does elimination but I was confused whether it would eliminate one bromine each from two rings and create a bond between bot... |
I absolutely love chemistry and I really want to take part in science fairs. I am also taking an AP chemistry class. Cleaner fuel and energy sources and air pollution (especially due to smog and vehicle exhaust) interest me. My initial idea was to make solar panels work along the lines of Chlorophyll, but that is a bit... |
What are some good research topics for a high school student? |
If you were a refinery, you'd throughput hundreds of tonnes/day from one reactor. To keep process volumes manageable, high gas pressures and fast throughputs. If you thermally cracked long chain alkanes, you would need red heat and get coking. If you did it over acid catalyst, typically zeolite whose pores define pr... |
There is a confusion here: "molecular system" is just a figure of speech, and there is no hard line between molecular systems and e.g. macroscopic solid bodies. It is not strictly about size of bonding type. If you use the definition of molecules as entities where the atoms are connected with covalent bonds then you wi... |
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