M.A.R.
  • Member for 7 years, 5 months
  • Last seen this week
  • Tabriz, Iran
What causes the old book smell?
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53 votes

This is a very interesting question. Provided that the materials used in making papers aren't the same around the globe, this is a very broad case of study. However, a study has been conducted in ...

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An introduction to "oxidation state"/"oxidation number"
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32 votes

#TL;DR; Oxidation States are useful tools used in nomenclature, redox chemistry etc. There are a few simplistic rules to determine the oxidation state of elements in an atom; but they're not ...

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Why would breathing pure oxygen be a bad idea?
29 votes

Our body is used to the environment around us. Once you change part of the environment, you have to be ready for the consequences. Inhaling pure oxygen is the cause for what is known as oxygen ...

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What is the meaning of the "dot" notation in chemical formulas?
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23 votes

By writing $\ce{AB.xCD}$ chemists mean that there are CDs are found in the crystalline framework of AB. The most common example of this is water trapped inside the crystal structure of ionic compounds....

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Are all NO3- salts soluble in water? If so, why?
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23 votes

No, the correct way of putting it is $$\mathrm{Almost~all~of~the~\mathbf{inorganic}~nitrate~salts~are~soluble~in~water. }$$ The families of organic nitrate salts are typically nitrates of azoles and ...

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How do I excel in Chemistry?
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23 votes

Chemistry needs a devoting reader. You should try to love chemistry as much as you want! That'll be the ignition for lots of reading and stuff. My pointers: Love chemistry. Learn in an organized ...

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Alkane, alkene, alkyne boiling point comparison
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22 votes

Disclaimer: All of this "jazz" will be about reaching a mere rule-of-thumb. You can't just compare whole families of organic compounds with each other. There are more factors to consider than below, ...

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Why is the specific heat of water high?
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18 votes

Water has hydrogen bonding in it. Hydrogen bonding is some kind of intermolecular force (a tutorial and the wikipedia page) that is usually seen in molecules that have $\ce{OH}$, $\ce{NH}$ or $\ce{FH}$...

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Is 3,5-diethyltoluene an accepted IUPAC name?
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13 votes

Names like toluene are "retained names". In chemistry, a retained name is a name for a chemical compound that is recommended for use by a system of chemical nomenclature (for example, IUPAC ...

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Why are water droplets shaped like that?
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11 votes

From the Wikipedia article on surface tension: Surface tension is responsible for the shape of liquid droplets. Although easily deformed, droplets of water tend to be pulled into a spherical shape ...

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Molecular formula of a hydrocarbon
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11 votes

You're right in thinking that it's an alkane. Now I think I shouldn't blame you for getting confused by $\ldots$ as a molecular formula which is mainly used in cars as fuel $\ldots$ Because ...

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Why don't polar and non-polar compounds dissolve each other?
10 votes

TL;DR It's because the enthalpy changes of a solution generally don't favor dissolution. A longer version: To explain this, usually the enthalpy change explanation is given. For the sake of ...

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Does Cute Poison actually work?
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10 votes

The Wikipedia page on "Cute Poison" episode says that it wasn't anhydrous copper (II) phosphate, but Gypsum. I haven't seen the episode, and the Wikipedia page's reaction seems to be the backwards ...

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Two liquids that react to produce a gas less dense than air at room temperature
9 votes

If the other products aren't significant, I'll recommend the all famous alkali metals' reaction with water: $$\ce{2Li(s) + 2H2O(l) -> 2LiOH(aq) + H2(g)}$$ Hydrogen gas is less dense than air, both ...

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Where does the name ‘aliphatic’ come from?
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9 votes

Olefins are hydrocarbons that contain at least a double bond. The term is used —sometimes misleadingly— interchangeably with alkenes. Although the nomenclature is not followed widely, ...

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Does benzene's resonance structure allow it to enter DNA?
9 votes

Um, what? Toluene — $\ce{C6H5CH3}$, a relatively more reactive derivative of benzene — is highly water-insoluble, so can't be easily disposed of body. A group of six (so is reported) ...

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Is ammonium a strong or weak conjugate acid?
8 votes

Consider these reactions: \begin{equation} \ce{HA + H2O <=> A- + H3O+}\tag{1} \end{equation} \begin{equation} \ce{A- + H2O <=> HA + OH-}\tag{2} \end{equation} The equilibrium constant ...

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Why does thallium form TlF and TlF3 but aluminium only forms AlF3?
7 votes

Ahh, Thallium is a very nice element. Because it's weird. The +3 oxidation states are favorable except for the heavier elements, such as Tl, which prefer the +1 oxidation state due to its stability; ...

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How to determine the sign of the enthalpy of formation?
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7 votes

$\ce{Al2O3}$, upon the formation of its lattice, releases heat. This heats up water. The increase in the temperature is in water, not $\ce{Al2O3}$. We usually refer to the water as the surroundings ...

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Ionic bond and ionic radii in FeS
6 votes

Iron and sulfur ions bond by electrostatic attraction. This is the right answer. I see a hard time maneuvering around it. Breaking an ionic bond between $\ce{Fe^2+}$ and $\ce{S^2-}$ ...

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Why is sulfur dioxide more stable to UV radiation than ozone?
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6 votes

I'm going to attempt to answer this from three points of view. Qualitative considerations and MO theory: First, why isn't ozone linear? You can imagine $\ce{O3}$ like a $\ce{CO2}$ molecule that lacks ...

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Is the fact that table salt is composed of Na & Cl a chemical or physical property?
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6 votes

The problem rises when we are mistaken about what a property is. The different types of matter can be distinguished through two components: composition and properties. UCDavis Do a search about ...

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How to cheaply extract iodine from an alcoholic solution?
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5 votes

Alcoholic solution of iodine What firstly comes to mind is that you meant "iodine tincture". This question must have been frequently asked, since answers are available out there with ...

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Constructing an equation for the precipitation of a salt
5 votes

Precipitation is usually a single or double displacement reaction, and refers to the formation of an insoluble, solid salt from soluble ions. For instance, silver bromide, $\ce{AgBr}$, is insoluble in ...

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How dangerous are these soil organic carbon digestion methods?
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5 votes

$\pu{0.1 M}~\ce{NaOH}$ is potentially corrosive when in contact with metals or human skin (see here), so I advise precautions such as wearing protective standard gloves and keep metals away from ...

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Utility of Delta G
5 votes

$\Delta G$ is a convenient way of determining the spontaneity of a reaction that takes place in constant temperature and pressure. As you might know, a positive $\Delta G$ would mean that the reaction ...

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Valency and chemical formula
5 votes

Max's comment sums it up. Beware, I'm gonna have to use many simplifications in order to explain this. A bit of introduction The species you mentioned are ionic compounds. For your level it's useful ...

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Oxidation state of the sulfur atoms in the thiosulfate Ion
5 votes

Yes, lewis structure does matter. Draw the lewis structure of thiosulfate. How is oxidation state measured? It's a crude way of attributing some charge to the atoms. O is more electronegative ...

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Is Saliva an acid or base?
5 votes

I can count four reasons that say saliva pH isn't the same among humans: As people age, the composition of saliva changes in their body; this is easily explainable with the fact that the body isn't ...

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Why is it obligatory to cool down the container of a sample to measure its mass in a lab?
5 votes

Your gut feeling is right: Very hot crucibles can cause damage to the balance. However, this isn't the main reason for why chemists cool their samples down before measurement. We are all familiar ...

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