oxidation numbers problem (1 Viewer)

[clicker]

what is the oxidation number of Bi in NaBiO3

 

[queenie]

isnt it:

0 = Bi + 1 + (-3x2)
so Bi = +5?

 

[xiao1985]

affirmative on queenie...

5+

 

[Will Hunting]

isnt it +5?

Right on the mark The compound's sodium bismuthate and it's often used as an oxidising reagent in experiments involving cation separation. In those scenarios, bismuth from the NaBiO3, in sol'n, oxidises cations less electronegative than itself. That's how it can sometimes have a valency of 3+ as well as 5+.

 

[lfc_reds2003]

thanks for tthat will...

 

[funking_you]

Can't you just feel the love in these forums.

Keep up the good work people!

 

[AntiHyper]

How about FeSO₄? I'm always confused with the introduction of 2 non-metals.

 

[shafqat]

How about FeSO₄? I'm always confused with the introduction of 2 non-metals.

remember oxygen is usually -2, unless bonded to itself (and fluorine i think :S)
and also sulfate ion has charge -2. So Fe is +2, and since there are 4 oxygens sulfur must be +6 to balance it up.

 

[Casmira]

precisely where is oxidation number is learnt? i totally forgot how it works, the only books I have on hand (for prelim) is spotlight chemistry, i could try and borrow conq chem ...

 

[richz]

conq chem is no good try and get chem contexts for oxidation numbers.
anyway for the q

0= 3*-2 + 1 + Bi
Bi = +5

 

[richz]

precisely where is oxidation number is learnt? i totally forgot how it works, the only books I have on hand (for prelim) is spotlight chemistry, i could try and borrow conq chem ...

used to tell which one is under oidation and which one is in reduction. A decrease in oxidation number = reduction increase = oxidation

 

[azza_3761]

Heres a summary of oxidation numbers:
The oxidation state of a chemical species is a measure of the degree of oxidation. These are determined by a few rules:
• Uncombined elements or Sum of a combined molecule = 0
• Ions or Sum of polyatomic ions = their charge
• Hydrogen usually +1, Oxygen usually -2
Oxidation states can be used to describe electron transfer in redox reactions:
• Oxidation involves the increase in oxidation state
• Reduction involves the decrease in oxidation state

 

[nit]

Originally posted by shafqat

remember oxygen is usually -2, unless bonded to itself (and fluorine i think :S)

Oxygen can also be in the 1- state in peroxides, and in the "-1/2" state in superoxides which mainly occurs for potassium and rubidium I think. And hydrogen can be in the 1- state in hydrides. Those are the major exceptions to the rules.

Originally posted by Will Hunting

That's how it can sometimes have a valency of 3+ as well as 5+.

The existence of the two states for Bismuth, and group 13 species such as Thallium, Indium and for group 14 species such as Tin and Lead is due to the inert s pair effect - the relativistic contraction of s orbitals which results in increased penetration of these electrons, thus making them more difficult to remove. Electronegativity isn't as directly important in explaining the variability in stable states for these ions - rather it can be thought of as consequential to this inert s-pair effect.

 

[Jumbo Cactuar]

And oxidation states of iron;

Fe(-II) - [Fe(CO)4]2-
Fe(0) - [Fe(CO)5]
Fe(II) - [Fe(H2O)6]2+ , [Fe(en)3]2+
Fe(III) - [Fe(edta)(H20)]-
Fe(IV) - [Fe(As~As)2Cl2]2+
Fe(VI) - [FeO4]2-