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Chemistry / Is the molar mass applicable to both the atomic mass and molecular mass?
« on: 17/09/2018 17:47:28 »
Is the molar mass applicable to both the atomic mass and molecular mass?
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In order to have the octet of each atom filled, an extra electron is required. Here is a website that shows the structure of the nitrite ion. Count the number of valence electrons that each atom contributes: https://chemfiesta.org/2015/09/18/resonance-structures/From where does this ion get an extra electron?
The exchange benefit comes whether the orbital is filled or not.What do you mean by 'there are two sets of 3 equivalent electrons? As I know there are three sets of electrons in p orbitals. Could you let me clarify it, please?
If all p orbitals are half filled, then there are 3 equivalent electrons (one in each p orbital, and all with the same spin, let's say it's "up"). If all the p orbitals are filled then there are two sets of 3 equivalent electrons (the three "up" electrons can exchange, and the three "down" electrons can exchange.)
It has to do with the "exchange energy," which is a measurement of the energetic benefit of having multiple electrons with the same energy and same spin.I understand the concept of half-filled orbitals. They are more stable because they have single electrons with one directional spin But what's about fully filled orbitals because each orbital has two electrons with opposite spins. In the case of full-filled orbitals, how the orbitals can be more stable? Could you explain it, please?
It is a fairly complex topic, and is related to quantum mechanics that is probably far above what is require for the course you are taking, but you can read about it here: https://en.wikipedia.org/wiki/Exchange_interaction
The important thing to know is that the more electrons there are with the same energy and same spin in a small area, the more stable the arrangement is.
↑ ↑ ↑ ↑ ↑
is more stable than
↑ ↑ ↑ ↓ ↓
because in the top case, all of the electrons are equivalent and can exchange with each other, while in the bottom case, there is only a triple and a double.
The exchange energy is maximized when orbitals are half filled and completely filled.
You mean to say If I split H2SO4, we get 2H+ + SO4²⁻, and one H+ combined to form HSO4⁻. After that Na+ from NaOH combined to HSO4⁻ and form neautral compaund NaHSO4? Please let me clear.So why Na+ is combined to HSO4?Na+ and HSO4 - have opposite charges and attract each other.
It is an acid/ base reaction.I got it. But I have two questions from the equation below
A proton is transferred, which is pretty much the definition.
NaOH + H2SO4 = NaHSO4 + H2OSo, which compounds take part in oxidation-reduction reactions?
Any compound can take part in an oxidation-reduction reaction as long as the result of the reaction is a change of the oxidation state of the atoms present. In order to know if an oxidation state has been changed, you need to be able to count how many electrons "belong" to particular atoms. If an atom gains electrons, then it has been reduced. If it loses electrons, it has been oxidized. For example, take the following reaction:
2Ca + O2 → 2CaO
In this reaction, the two calcium atoms and the two oxygen atoms start out with an oxidation state of zero because they are neutral. After the reaction, the calcium atoms have lost electrons to the oxygen atoms, forming Ca2+ and O2-. Since the calcium atoms lost electrons, they were oxidized. Since the oxygen atoms gained electrons, they were reduced.Quoteand what's the name of this reaction?
It's an acid-base reaction. An acid is a substance that donates protons whereas a base is a substance that accepts protons. More specifically, that is the definition of a "Bronsted acid" or a "Bronsted base".
So, which compounds take part in oxidation-reduction reactions? and what's the name of this reaction?NaOH + H2SO4 = NaHSO4 + H2O
So which compound is oxidized and which one is reduced in the reaction?
None of them, actually. Acid-base reactions are not necessarily also oxidation-reduction reactions. In this case, the oxidation states of all of the atoms present does not change.
NaOH + H2SO4 = NaHSO4 + H2OHow should I know that 'Only one hydrogen is replaced (By sodium)'?
The chemical equation you posted tells you. It forms NaHSO4, not Na2SO4. Only one of the hydrogen atoms is removed from the sulfuric acid in that reaction.
My question is 'why does an element become stable'? what is the necessity?Why is O2- less reactive?
I told you, it's because it has a full valence electron shell. Since neutral oxygen atoms only have 6 valence electrons, that gives it room to accept 2 more electrons in order to fill up its shell. Reacting with other atoms is how it can gain those extra electrons. Since O2- already has all 8 valence electrons, it doesn't have room to accept any more electrons from other atoms.
All oxygen atoms are stable unless they are of a radioactive isotope. Perhaps what you meant was "reactive" versus "unreactive"? Atoms prefer to have their outer electron shells filled, which is why O2- is less reactive than O.Why is O2- less reactive?
How should I know that 'Only one hydrogen is replaced (By sodium)'?But in this reaction, NaOH + H2SO4 = NaHSO4 + H2O how to calculate the equivalent weight of H2SO4?
Only one hydrogen is replaced (By sodium).Equivalent weight = molecular weight/number of H+ replaced
As you said 'No, because sodium isn't a diatomic molecule like chlorine is'0.5 Cl atom
I believe you mean 0.5 Cl2 molecule, not 0.5 Cl atoms.QuoteIf I take NaCl a mole of molecules, then there are 2 moles of Na and 2 moles of Cl₂ molecules in both sides or 1 mole of Na and 0.s moles of Cl₂ molecules present.
That would be 0.5 moles of Cl2.QuoteNow my second question is If Cl₂ = 2Cl both mean 2 Cl atoms or 2 moles of Cl atoms, Can I write here Na₂ instead f 2Na such as Na₂ + Cl₂ = 2NaCl?
No, because sodium isn't a diatomic molecule like chlorine is.
1. Na + 0.5Cl₂ = NaClBut how is it possible? If you say 1 mole of Na+ and 1 mole of Cl- form 1 mole of NaCl, then I can write 'Na+ + Cl- = NaCl' but as we know 1 + 1 make 2. So 1 mole of Na+ and 1 mole of Cl- should make 2 moles of NaCl or 2NaCl?
Could you please explain it?
Balance your equation. Count the number of sodium atoms and chlorine atoms on each side. That should give you your answer.