In my NCERT textbook, in the chapter 'The d- and f-block elements', the last paragraph under oxides and oxoanions of metals goes like:

$...$ $\ce{V2O5}$ is, however, amphoteric though mainly acidic and it gives $\ce{VO4^3-} \space\text{&}\space\ce{VO2+}$ salts $...$

What do they actually mean by the phrase amphoteric though mainly acidic?

Wikipedia clearly states that,

Vanadium(V) oxide (vanadia) is the inorganic compound with the formula $\ce{V2O5}$. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because of its high oxidation state, it is both an amphoteric oxide and an oxidizing agent. From the industrial perspective, it is the most important compound of vanadium, being the principal precursor to alloys of vanadium and is a widely used industrial catalyst.

What could the author mean?


I got information from Poutnik that the phrase in concern means that $\ce{V2O5}$ has more of an acidic character than basic character and thus it is known as 'amphoteric though mainly acidic'.

Now my question is, what are the factors which determine whether the basic or the acidic character dominates in an amphoteric compound?

  • 3
    $\begingroup$ The Q can be too broad, as you mere ask what determines the strength of an acid or a base. The rest, related to amphoterism, is just comparative arithmetics. $\endgroup$
    – Poutnik
    Mar 30 at 9:47
  • $\begingroup$ So now I'll look for answers for factors determining strength of acid / base? Thank you @Poutnik! $\endgroup$
    – Chem-geek0
    Mar 30 at 9:48
  • 2
    $\begingroup$ General answer is not much smaller than chemistry. But narrowing it to character of metal oxides, the rule of thumb is that with increasing of metal oxidation state the oxide basicity gets weaker and acidity stronger. Compare with Na2O, MnO, Al2O3, TiO2, CrO3, WO3, Mn2O7. The first is basic, the last acidic. $\endgroup$
    – Poutnik
    Mar 30 at 9:55
  • 2


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