Questions tagged [oxidation-state]

Oxidation state is a concept, which assigns hypothetical charges to atoms in compounds. This tag should be applied to questions which relate to that concept or to oxidation states in atoms of compounds.

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16
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2answers
5k views

Electronegativity Considerations in Assigning Oxidation States

I have never seen anything other than a set of rules like these when textbooks present how to assign oxidation numbers. Such as these: However, if we keep in mind that oxidation numbers are simply ...
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1answer
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An introduction to “oxidation state”/“oxidation number”

I just can't get my head around oxidation states. They're really confusing! Why do I need to assign a number to some element? What are oxidation states? How and why should we assign oxidation states? ...
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Is iron in the brown ring compound in a +1 oxidation state?

In the standard brown ring test for the nitrate ion, the brown ring complex is: $$\ce{[Fe(H2O)5(NO)]^{2+}}$$ In this compound, the nitrosyl ligand is positively charged, and iron is in a $+1$ ...
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1answer
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What allows sulfur and phosphorus to expand their octet?

There are many compounds in which the stability of a molecule is not governed by the presence of octet configuration in central atom. In most of the cases the central atom is generally sulfur or ...
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3answers
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Oxidation state of the sulfur atoms in the thiosulfate Ion

What are the oxidation states of the two inequivalent sulfur atoms of the $\ce{S2O3^{2-}}$ molecule? For all I know is that Lewis Structure does matter in most of the cases.
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1answer
319 views

Why don't we see these lanthanide species?

For most lanthanide metals$^{[1]}$, the stable oxidation state is III. The general electronic structure$^{[2]}$ is $$\ce{[Xe] 4f^{0}^{-14} 5s^2 5p^6 5d^{0}^{-1} 6s^2}.$$ Elements that have the d-...
15
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1answer
712 views

Plutonium having more oxidation states than samarium?

Why does plutonium have more oxidation states than samarium? Electron configuration of Pu: $\ce{[Rn] 5f^6 7s^2}$ Electron configuration of Sm: $\ce{[Xe] 4f^6 6s^2}$ I thought that only the valence ...
10
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1answer
10k views

How to balance more complex redox reactions?

I'm in an advanced level chemistry course, and so far we've been introduced to balancing redox reactions. The basic ones like $$\ce{MnO4- + Cl- -> Mn^2+ + Cl2}\tag1$$ are pretty easy for me, but ...
19
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6answers
5k views

Do atoms form either a positive or a negative charge, but not both?

I do not mean at the same time, of course, but I mean it appears from an overview of the common charges formed from ionizing various elements that each element forms one or more of either positive or ...
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4answers
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What should be the oxidation state of oxygen in HOF (hypofluorous acid)?

What should be the oxidation state of oxygen in $\ce{HOF}$ (hypofluorous acid)? Sources on the internet have confused me. Most state its oxidation state to be 0, while the others state that it is -2 (...
15
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1answer
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What is the nature of the Fe–O2 binding in oxymyoglobin and oxyhemoglobin?

Deoxymyoglobin ($\ce{Mb}$) is known to have iron in the +2 oxidation state; I believe this was deduced from its magnetic moment, which corresponds to four unpaired electrons in high-spin $\mathrm{d^6}$...
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Why does carbon monoxide have a greater affinity for hemoglobin than oxygen?

Hemoglobin is an iron-containing oxygen transport metalloprotein in the red blood cells of most mammals. Simply put, it's a carrier protein. Interestingly it doesn't carry carbon dioxide in the same ...
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3answers
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Oxidation state of fluorine in HOF

What should be the oxidation state of $\ce{F}$ in $\ce{HOF}$. As fluorine is the most electronegative element in the periodic table, it should be $-1$. But when I googled it, I found that many ...
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3answers
9k views

Oxidation states of oxygen

I'm given a question: Oxidation number of $\ce{O}$ in $\ce{BaO2}$ is $x$ and in $\ce{OF2}$ is $y$; then the value of $x+y$ is what? Now my main question is that if $\ce{F}$ has $-1$ valency in $...
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0answers
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Predominance of III oxidation state for lanthanides [closed]

For most lanthanide metals, the stable oxidation state is III [*]. The general electronic structure is $$\ce{[Xe] 4f^{0}^{-14} 5s^2 5p^6 5d^{0}^{-1} 6s^2}\ \ [**].$$ Elements that have the d-electron ...
16
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1answer
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Why can Cu have an oxidation number of +2?

The electronic configuration for $\ce{Cu}$, adjusted for Hund's rule, is: $[\ce{Ar}] 3d^{10} 4s^1$ So, shouldn't $\ce{Cu}$ have an oxidation number of $+1$? whereby it gives off its outermost 4s ...
24
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3answers
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Is it possible for one specific atom in a molecule to have a non-integer oxidation state?

I am wondering if fractional oxidation states of an atom are possible. I'm not referring to cases such as $\ce{Fe3O4}$ or $\ce{Mn3O4}$ where the average oxidation state is fractional, since these ...
5
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4answers
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Are fractional oxidation states possible?

To get the oxidation state of carbon (denoted $x$) in octane, $\ce{C8H18}$, I used the fact that hydrogen has an oxidation state of $+1$: $$8x + 18\cdot 1 = 0 \qquad \Longrightarrow \qquad x = -\frac{...
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2answers
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Why do heavier transition metals show higher oxidation states?

In p-block elements, higher oxidation states are less stable down the group due to the inert pair effect. This is not the case for transition metals. Why do heavier transition metals show higher ...
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2answers
731 views

Oxidation of Carbons

In which of the reactions below is the first compound in the equation NOT oxidized? The correct choice is (D), which can be seen through process of elimination, but I was wondering how to do this ...
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1answer
92 views

How to differentiate the notation of a compounds charge and an anions oxidations state?

I have had the case a few times. Being given something of this form: $$\ce{Cr2O7^2-}$$ How do I know whether the $2-$ is referring to the oxidation of the oxygen anion or the charge of the whole ...
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2answers
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The teacher insists that iodine oxidation number in iodate ion is 7

What started as this question http://chemistry.stackexchange.com/questions/67756/is-it-possible-to-use-the-school-supplied-algorithm-to-build-the-lewis-diagram-o continued with an email from the ...
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3answers
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Oxidation number of phosphorus in phosphine

Electronegativity of $\ce{H}$ is greater than $\ce{P}$, but according to my book in $\ce{PH3}$, $\ce{P}$ has oxidation number of -3. How is it possible? Is any of the data wrong?
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1answer
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Why does tin form tin (II) compounds?

The stability of the +II oxidation state in lead has been widely attributed to the so-called “inert pair effect”: the 6s subshell is stabilized through relativistic contraction due to the near-c speed ...
12
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2answers
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Does fluorine in FNO3 have +1 oxidation number?

According to my textbook and also Wikipedia, fluorine nitrate is a compound which can be created (though it is unstable). Also my textbook says that fluorine has a $+1$ oxidation state. But how is $+1$...
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2answers
965 views

Is ClH7 possible? [duplicate]

Chlorine can be $sp^3d^3$ hybridized. If so, it can form $\ce{ClH_7}$ and then chlorine, being more electronegative, will have (-7) as its oxidation number. But we know that the oxidation number of $\...
5
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1answer
2k views

Difference between oxidation and formal charge

What is the difference between oxidation number and formal charge? I am confused about the two.
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1answer
220 views

Stability of 3d metal fluorides and iodides in different oxidation states

I read that the fluorides of 3d metals in lower oxidation states, e.g. $\ce{VF2}$, $\ce{TiF2}$, and $\ce{CuF}$ are thermodynamically unstable. For example, $\ce{CuF}$ disproportionates to $\ce{Cu + ...
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1answer
333 views

Why are electrons shared equally when calculating formal charge, but unequally when calculating oxidation state?

When calculating formal charge - electrons are shared equally between the atoms in the bond. When calculating oxidation state - electrons are both given to the most electronegative atom. Why is this ...
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2answers
6k views

How to find out oxidation state when compound has multiple electronegativities

How do I solve for oxidation state in something like CH3-O-F? The fluorine is more electronegative than the oxygen which is more electronegative than the carbon which is more electronegative than the ...
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3answers
15k views

Is there any way to determine if the compound is oxide or peroxide or superoxide?

I know that in an oxide oxygen's oxidation number is $-2$, in a peroxide oxygen's oxidation number is $-1$ and in a superoxide oxygen's oxidation number is $-\frac12$. So, how will I be able to detect ...
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1answer
123 views

When will peroxide form?

A very typical example of a compound of peroxide is $\ce{H2O2}$. When like the title says, will such compounds form, despite usually oxygen will have a oxidation number of 2-?
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4answers
780 views

How is it possible to obtain a value of 8/3 as an oxidation state?

Iron's oxidation state in $\ce{Fe3O4}$. I really can't get the logic behind this.
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1answer
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How is the triferric tetroxide of iron possible?

If oxygen has a valency of $-2$, $4$ of it would result in $-8$. But iron doesn't have a (variable) valency of anything that goes to $-8$. Then how is $\ce{Fe3O4}$ possible?
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2answers
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Why is NH2 negatively charged?

Whenever I look up the Lewis structure for $\ce{NH2^-}$, it shows 8 electrons. Now I understand the octet rule, but I still don't see how an electron can just appear from nowhere. There are 5 valence ...
4
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1answer
141 views

Unusual oxidation states of alkali metals

When going through list of oxidation states on Wikipedia I encounterd there that sodium, potassium, rubidium and caesium exhibit oxidation states of -1, but not lithium, even though its ...
4
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2answers
221 views

What's the relation between the octet rule and quantum exclusion and how is it related to oxidation state?

What in the quantum nature of electrons gives rise to the octet rule? How is it related to the fact that an element cannot have an oxidation state higher/lower than the complementary to 8?
4
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1answer
141 views

How does radiation facilitate the formation of tetravalent iron?

In reading the article abstract What Oxidation State of Iron Determines the Amethyst Colour?, the author states that in regards to the gemstone amethyst, from clear quartz: The crystal was ...
3
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1answer
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Why is Mo(VI) more stable than Cr (VI)?

Acids of $\ce{Mo}^\mathrm{VI}$ are more stable than those of $\ce{Cr}^\mathrm{VI}$ in terms of redox reactivity. In p-block elements, as we go down the groups, the stability of lower oxidation state ...
3
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1answer
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Why isn't thallium triiodide stable?

We know that stability of higher oxidation state (+3) decreases and stability of lower oxidation state (+1) increases, so thallium is most stable in its +1 oxidation state due to the inert pair effect ...
2
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1answer
5k views

What are the oxidation states of sulfur in the tetrathionate ion?

What are the oxidation states of the sulfur in the tetrathionate ion $\ce{S4O6^{2-}}$?
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1answer
3k views

How to assign oxidation number of sulfur in thiocyanate anion?

Recently I was trying to balance a redox chemical equation: $$\ce{CuSCN + KIO3 + HCl <=> CuSO4 + KCl + HCN + ICl + H2O}$$ The equation is in principle simple to solve; one element ($\ce{I}$) ...
2
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1answer
10k views

Why is sodium chloride edible whereas both sodium and chlorine are highly reactive?

Sodium chloride is edible. But elemental sodium and chlorine are highly reactive and poisonous. What is the difference? Also, is there any difference in eating sodium chloride in powder form and ...
2
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1answer
1k views

Which element is being reduced in this reaction?

Which element is reduced in this reaction: $$\ce{2KMnO_4 +3NaSO_3 +H_2O ->2MnO_2 +3NaSO_4 +2KOH}$$ I am trying to figure out which elements lose their electrons, but how am I supposed to know ...
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1answer
94 views

Why can some ions have different valence?

Like $\ce{Fe}$, it can be $\ce{Fe^{2+}}$ or $\ce{Fe^{3+}}$, same with $\ce{Ni}$ and $\ce{Co}$, what determines whether the ionic compound will be $\ce{Fe^{2+}}$ or $\ce{Fe^{3+}}$?
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1answer
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How do I find the oxidation number of a coordination complex

I actually know how to calculate the oxidation number for coordination complexes but some complexes like the below are giving some reistance $\ce{[Cu(NH3)_2][Fe(H2O)_3]}$ (diamminecopper(?) ...
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1answer
605 views

Difficulty understanding redox in terms of hydrogen and oxygen transfer?

I have come across 4 ways of defining oxidation: loss of electrons increase in oxidation number gain of oxygen loss of hydrogen From these definitions, I have an idea of what I think 'oxidation' and ...
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1answer
64 views

Question About Reversible Reactions and Batteries

So my book says that the batteries we have considered so far( Daniell cells) are low life span, because they reach equilibrium too fast. In the next paragraph, it says they are also made by ...
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1answer
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Iodate ion and Octet rule

'm trying to figure out why the oxidation state of the iodate ion is +5. The iodine atom has 7 electrons in its outermost shell (comprised of s and p sub-shells). Two oxygen atoms receive 2 electrons ...
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3answers
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Oxidation State Of Propene

I was just trying to understand the oxidation states of organic compounds. A more electronegative atom than carbon increases it's oxidation state by 1 and less electronegaitve atom decreases it's ...