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8
votes
1answer
333 views

What does it mean when “a gas is dilute in CO₂”?

I'm reading an article about carbon sequestration, and I came across a strange phrase: "The flue gas is dilute in $\ce{CO2}$". I can't quite ascertain its meaning from the context. I think it means ...
4
votes
1answer
792 views

What is the structure of this molecule?

I need to find the Lewis structure of the ion $\ce{SCH^-}$. I think the Lewis structure should be: $\ce{S=C-H}$ with one lone pair on the carbon and two lone pairs surrounding the sulfur. Is this ...
2
votes
1answer
425 views

Lewis structures of molecules containing oxygen

As far as I know, when writing Lewis structures for molecules, we need to consider the octet rule and the valence electrons each atom has. But, if we take for example, the molecule $ Cl O_2^- $ , we ...
5
votes
1answer
446 views

Does this set of quantum numbers have a unique solution?

I received the following question: Complete the missing values for the four quantum numbers: $n=?$, $\ell = 2 , m_\ell = 0$ , $m_s= ? $ . The problem is that I think $n$ can be any number ...
6
votes
1answer
526 views

How useful is the assumption that water doesn't auto-ionize in the following?

Now in the first row of the iCe-table, $[\ce{H3O+}]$ is said to be 0. But water autoionizes to some extent, so it shouldn't really be 0. I accept that, because the pH of this solution is 2.5, the ...
2
votes
1answer
1k views

Are there ways to predict which chemicals will kill certain bacteria?

Are there ways to compute what chemicals kill a give bacteria but not another given bacteria ? Does that help much to make medication ?
7
votes
2answers
418 views

Why do H₂ and O₂ create H₂O?

Both $\ce{H2}$ or $\ce{O2}$ are stable molecules. However when given energy they heat up and form $\ce{H2O}$. My teacher explained that the increased energy breaks the bonds, allowing new ones to form....
2
votes
0answers
110 views

Maintaining a 40% CO₂ aqueous environment?

I wish to grow algae in a 40% $\ce{CO2}$ (water under air with 40% $\ce{CO2}$ content) aqueous environment. Simple DIY methods are available, but they are generally unreliable (For more info on DIY ...
3
votes
0answers
118 views

How much of the anion species is left over after the first precipitation?

Some barium chloride is added to a solution that contains both $\ce{K2SO4}$ ($\pu{0.050 M}$) and $\ce{Na3PO4}$ ($\pu{0.020 M}$). (a) Which begins to precipitate first: the barium sulfate or the ...
6
votes
2answers
562 views

What meaning do multiple real solutions of a truncated virial equation have, if any?

Let's say I truncate the virial equation after the third term for use as my equation of state: $${P\over\rho RT}=1+B\rho+C\rho^2$$ I have tabulated values for $B(T)$ and $C(T)$. I know $P$ and $T$ ...
5
votes
4answers
2k views

Phase diagram for first 10 elements

I've been looking on the net for a reference which shows a phase diagram for elements at least from $\ce{H}$ up to $\ce{Ne}$. Specifically, I'm looking which of these elements can be solid or liquid ...
1
vote
1answer
3k views

Determining the exact charge of ions that will be formed by an atom using the periodic table

I don't know how to obtain the "exact charge of the ions" that will be formed by each atom mentioned. I also have to figure out whether they are positive or negative. Hydrogen, for example, can form ...
5
votes
1answer
860 views

What components of safety should be included in a chemistry laboratory experiment conclusion?

The focus of my question here is this: In a laboratory there is a Bunsen burner, a hot plate, hydrochloric acid, and concentrated ammonia. What would you mention about safety precautions? As students ...
3
votes
2answers
1k views

How do I find change in Gibbs free energy of water formation?

How do I find the change in Gibbs free energy of the reaction $$\ce{H2 + \frac{1}{2}O2 -> H2O}$$ when it is at $\pu{75^\circ C}$ and $\pu{1 atm}$? Do I calculate the Gibbs free energy of each ...
16
votes
3answers
7k views

Why does hand sanitizer turn into a liquid after coming out of the bottle?

Hand sanitizer is a gel in its bottle, but when I pour it on my palm, it turns into a free flowing liquid. Why does that happen? It doesn't turn to a liquid when I pour it on my floor or my table. ...
19
votes
4answers
19k views

Why are equilibrium constants unitless?

I haven’t quite reached the point where I can read a full-fledged text on chemical kinetics and thermodynamics yet, so bear with me, please. I’m wondering why a value like $K_\text{eq} = \frac{[\ce{...
2
votes
1answer
458 views

What causes reactions to react the way they do?

We were taught that there are primarily four kind of reactions, synthesis, combustion, single displacement, and double displacement. When the reactants are given to you, the reaction can be predicted. ...
-4
votes
1answer
3k views

What makes a molecule a polyatomic ion?

I checked the Wikipedia page, but it did not seem to provide a very intuitive explanation. What distinguishes a molecule such that it behaves like a polyatomic ion? I understand that it is a ...
3
votes
2answers
3k views

Why doesn't water play a role in reactions in aqueous reactions?

$$\ce{Ba(NO3)2(aq) + Na2CO3(aq)}$$ In the above reaction both the substances are in water, however water plays no role in the reaction. Why is it that although water is present in the reaction, it ...
1
vote
1answer
3k views

Is “ice point” the same as “freezing point”?

I am using an old book and they almost use both terms interchangeably sometimes. Do they mean the same thing? Similiarly for "steam point" and "boiling point"
0
votes
1answer
550 views

Why is it called “carbonation”?

Why is it referred to as "carbonation" and we drink "carbonated" beverages when carbonate is $\ce{CO3}$ while $\ce{CO2}$ (carbonite?) is present in carbonation?
5
votes
1answer
1k views

Is there a similar characteristic of the lanthanide contraction in the other transition metal groups?

Basically, does the lanthanide contraction also occur with the 4d, 6d groups as well? I am at a lack of understanding in this topic, I am just wondering what specific elements does this jump in a ...
1
vote
1answer
4k views

Percent composition of nitrogen in fertilizer

The question was posed as follows: Fertilizers supply the essential elements, nitrogen, phosphorus and potassium for plant growth. A bag of fertilizer contains 500g of ammonium sulfate, $ \small \...
8
votes
3answers
5k views

Methane seems to dissolve more readily in cold water. Why?

When you are diluting air in the system and/or properly evacuating it, you must consider water temperature. Methane is completely dissolved in water at 42 degrees Fahrenheit (5.5 C) but can be ...
5
votes
1answer
165 views

Simulation of a particle and chemical molecule

I am currently studying the basics of simulation and want to try out some experiments. It is a known fact that gold nanoparticles can bind to chemical groups which contains thiol (R–SH group). I want ...
5
votes
1answer
891 views

Does “covalent” AgCl (aq) exist and if so, how to quantify its concentration?

I am reading Ionic Equilibrium by James N. Butler. Using silver(I) chloride in excess aqueous chloride as an example it speaks of several forms: $\ce{AgCl (s)}$ i.e. the ionic crystalline salt, $\ce{...
25
votes
2answers
27k views

Why is water a dipole?

Water ($\ce{H2O}$) is a dipole. The reason why is simply because it is not symmetrical, there are more electrons on the oxygen side than on the hydrogen side, and the electronegativity of oxygen. But ...
3
votes
1answer
3k views

How to extract pure caffeine from tablets?

I have some caffeine tablets and I want to extract the pure caffeine from the rest of the ingredients (caffeine 200 mg. Inactive ingredients in order are corn starch, dextrose, dicalcium phosphate, D&...
4
votes
2answers
1k views

Why must an oxidizer not touch rubber?

Why is it that oxidizers (specifically $\ce{KClO3}$) are at risk of causing a fire when they come into contact with the rubber stopper used to contain them in their container, but can be slowly heated ...
8
votes
1answer
46k views

Calculating the heat capacity of a calorimeter

I've been struggling with this problem that I can't seem to figure out. I think I know how to solve it but I think there's missing information. The combustion of 1 mole of glucose $\ce{C6H12O6}$ ...
7
votes
1answer
1k views

What determines the electronegativity of an element?

Is it possible to work out without post-Bohrian mathematics?
4
votes
1answer
4k views

Inherent error in mass and volume?

In one of my chem classes I had to do a lab that involved finding the mass and volume of a substance. I did three trials and for my mass I got 9.3g, 9.3g, and 9.4 g. For my volume, I got 9.7ml, 9....
19
votes
2answers
174k views

Will alcohol or soap damage plastic or rubber?

I have read conflicting advice on various sites about the appropriate methods for cleaning plastic and rubber items and would like to ask people who actually know what's going on what they would ...
7
votes
1answer
219 views

What is the 'ancestral term' in the LS coupling scheme?

On the physics.nist.gov site: http://physics.nist.gov/Pubs/AtSpec/node06.html The table titled "Atomic structural hierarchy in LS coupling and names for the groups of all transitions between ...
9
votes
0answers
428 views

multielectron spin-orbit coupling and energy level

For multi-electron atoms for which the Hamiltonian (including the spin-orbit coupling) reads $$H=\sum_i T_i-Z\sum_i V_i+\sum_i V_i^{\text{s.o.}}+\sum_{i>j}V_{ij}$$ The $T_i$ are the kinetic ...
5
votes
2answers
946 views

Is there an alternative to the half-reaction method to solving red-ox reactions?

The equation for the reaction between a permanganate and iron(II) ions in acidic solution is: $\text{MnO}_4^- + \text{Fe}^{2+} \longrightarrow \text{Fe}^{3+} + \text{Mn}^{2+}$ My book, as well as a ...
18
votes
2answers
446 views

Can molecules diffuse upstream when emptying a cup of tea?

I was drinking some tea, and I randomly decided to pour some into the toilet in an unbroken stream; can particles travel "upstream" quickly enough to reach the mug of tea? How fast can diffusion occur ...
8
votes
2answers
2k views

Is there any scenario in which the size of a molecule increases due to an increase in temperature?

Take an ice cube for example. Heat is applied in a closed container until it is vaporized completely. Will the molecule's size be larger (on average)? Is there a substance that you know of that has ...
1
vote
1answer
776 views

Do dishwashing detergent and stain remover powder/stick have the similar ability to remove collar rings?

For yellow rings on shirts caused by skin grease or sweat: Some recommended to use an "Oxyclean" stain remover or stain remover stick for cleaning. Some recommended to use dishwashing detergent to ...
2
votes
2answers
179 views

Are words on my T-shirt removable? [closed]

I wonder if the words on my T-shirt are removable? If yes, what kind of (chemical or physical) ways are there? They look like paints on the cloth, as the letter "C" has become blurred in the way ...
6
votes
2answers
131 views

Why do collisions in elementary reactions of higher-orders appear to be more likely?

So we are told that a unimolecular elementary reaction has a rate law of $k[\text{A}]$ where a termolecular reaction with three unique reagents, $A$, $B$ and $C$ has a rate law of $k[\text{A}][\text{B}...
7
votes
1answer
703 views

What is known about the phase of matter at very high temperature and enough pressure?

Are there theoretical reasons for or against the existence of materials that will not become solid at some fixed, sufficiently large temperature when enough pressure is applied? Or is this even the ...
1
vote
2answers
2k views

deduce chemical properties of a compound from elements

If we know the properties of two elements e.g Oxygen and Hydrogen. We know the following properties sound speed boiling point melting point refractive index etc. given that information, is it ...
6
votes
2answers
8k views

Is tin and tinware toxic?

I tried to find info on tin toxicity but there is not much. Wikipedia here says that it is not very poisonous; but there could be cases. My question is: is it dangerous to say have a coffee boiled ...
4
votes
1answer
2k views

Moment of inertia for a triatomic molecule

What does the moment of inertia for a molecule mean? How is it useful? Most importantly, how would I go about solving it for a triatomic molecule?
10
votes
1answer
928 views

Isolating salt from sea water using filters

Could a filter be used to isolate salt from sea water? Could we say that the water molecules are smaller than the molecules of salt dissolved in the water. I have no relation to chemistry or physics, ...
12
votes
2answers
13k views

Why are alcohols with longer chains less polar?

In my self-study, I recently came across the following question: "Choose the solute of each pair that would be more soluble in hexane ($\ce{C6H14}$). Explain your answer. (a) $\ce{CH3(CH2)10OH}$ or $...
0
votes
1answer
551 views

Product/(s) of the following reaction

I was wondering what the product will be in the following reaction: $$\ce{H3COOCH3 ->[\ce{H+}]} \:?$$ I was thinking about $\ce{CH3COOH}$ being a product but I do not know the mechanism.
3
votes
1answer
6k views

Reaction between potassium permanganate, alum, and sodium hydrogen sulfite

When I was a teenager, I played with a chemistry set. I tried adding potassium permanganate, alum, and sodium hydrogen sulphite (not sodium hydrogen sulphate) to water. Upon adding the third ...
1
vote
1answer
103 views

Methods: Does failing at intermolecular properties mean the same for intramolecular properties?

Let us consider the following: 1.) Method X fails at describing intermolecular non-covalent interactions. 2.) Method X excels at describing molecules of type Y. 3.) Method X ___?___ at describing ...

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