Explain how and why the basicity of an oxo anion depends on...

Explain how and why the basicity of an oxo anion depends on its charge, the number of oxo groups present, and the electronegativity. Use your reasoning to try to predict the approximate basicity of the following more complicated oxo anions: $\left(\mathrm{O}_3 \mathrm{P}-\mathrm{O}-\mathrm{PO}_3\right)^{4-}$ (pyrophosphate ion); $\left(\mathrm{O}_3 \mathrm{P}-\mathrm{O}-\mathrm{PO}_2-\mathrm{O}-\mathrm{PO}_3\right)^{5-}$ (tripolyphosphate ion).

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Key Concepts

Impact of Oxo Groups

The number of oxo groups in an anion affects its basicity by influencing both inductive and resonance stabilization effects. Each additional oxo group not only contributes to the overall negative charge but also withdraws electron density from the reactive centers, potentially decreasing the strength of the basic sites due to enhanced charge delocalization.

Electronegativity

Electronegativity refers to the tendency of an atom to attract electrons. In oxo anions, highly electronegative atoms draw electron density towards themselves, thereby reducing the electron availability at the basic sites. This withdrawal of electron density by electronegative atoms serves to diminish the overall basicity of the anion.

Basicity

Basicity is the measure of a species' ability to accept a proton. It is closely linked to the electron density available on the species, which is influenced by factors such as overall charge and the distribution of that charge across the molecule.

Charge Effects

The overall negative charge of an oxo anion generally increases its basicity by providing additional electron density for proton capture. However, when this charge is delocalized over several atoms, the effect can be moderated, reducing the localized electron density that is crucial for protonation.

Transcript

00:13 And this, now we do problem 106.

00:16 Well, you have to draw the structure for also phosphate.

00:20 Okay.

00:24 And we have to find how many ionization ionize proton, right? and so from the, the, every acid fophoric we know.

00:42 For example, with this, right? we get this one.

00:48 Always guess this ball, right? in the compound you should have one ball of the bond with oh and double bond with oxygen.

00:58 So keep that in mind we can write the structure of this ion.

01:15 Now let me let me throw some statements first.

01:20 So you must have p double bond oxygen and p .o .h.

01:47 And i had the v -o -4, joy, yeah, all atom.

02:25 We build that in our minds, so we can write a structure.

02:31 Okay, so we imagine our mind.

02:51 Now we try this, this problem is difficult for you.

02:56 It's not easy.

03:01 So i made the link and they combine together, okay? and now we, i know this soup has, double ball, double ball, okay? now, let's this one.

03:17 Because we don't get oxygen here, hydrogen here, so we just like this one.

03:26 And now when you do formal check, you know this, minus, minus, right? this will be get minus here.

03:35 Let me use another color.

03:40 With the formal check, we know this, six, six electron, minus one bomb, and minus six, electron available...

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