Question

What would be the formula for diphosphorus pentoxide?

Answer 1

`P_2O_5` as written, but this is an empirical formula.

Explanation:

`P_2O_5` is of course an empirical formula. The actual oxide is `P_4O_10`, with an adamantane structure.

Answer 2

Here's my thought process:

• From name: phosphorus `->` `"P"`
• "di" `->` `2`
• From name: oxide `->` `"O"`
• Anion stem: "ox"
• "pent" (instead of "penta", since "ox" starts with a vowel) `->` `5`

`->` `"P"_2"O"_5` (empirical formula)