Something's been bothering me all week...

[Rayquarian]

Dihydrogen Monoxide is the molecular compound H20, while hydrogen hydroxide is the ionic compound HOH.  Both are considered to be water.  Can something explain this?

[HTA!]

Isn't there something called hard water?

I'm guessing one is empirical and one is scientific?

[Daft Pink]

Well, both of them have 2 Hydrogens and 1 Oxygen, so in that way, they're the same. The thing is, they're probably arranged differently, so I don't see how they could be considered the same. As far as I know, there's no way they would be the same. D:

[Friendly Hostile]

The accepted IUPAC name of water is simply "water" (or its equivalent in a different language), although there are two other systematic names which can be used to describe the molecule.

The simplest and best systematic name of water is hydrogen oxide. This is analogous to related compounds such as hydrogen peroxide, hydrogen sulfide, and deuterium oxide (heavy water). Another systematic name, oxidane, is accepted by IUPAC as a parent name for the systematic naming of oxygen-based substituent groups,[23] although even these commonly have other recommended names. For example, the name hydroxyl is recommended over oxidanyl for the –OH group. The name oxane is explicitly mentioned by the IUPAC as being unsuitable for this purpose, since it is already the name of a cyclic ether also known as tetrahydropyran in the Hantzsch-Widman system; similar compounds include dioxane and trioxane.

[edit] Systematic nomenclature
Main article: Dihydrogen monoxide hoax

Dihydrogen monoxide or DHMO is an overly pedantic systematic covalent name of water. This term has been used in parodies of chemical research that call for this "lethal chemical" to be banned. In reality, a more realistic systematic name would be hydrogen oxide, since the "di-" and "mon-" prefixes are superfluous. Hydrogen sulfide, H2S, is never referred to as "dihydrogen monosulfide", and hydrogen peroxide, H2O2, is never called "dihydrogen dioxide"

Thank you Wikipedia.

[Rayquarian]

The accepted IUPAC name of water is simply "water" (or its equivalent in a different language), although there are two other systematic names which can be used to describe the molecule.

The simplest and best systematic name of water is hydrogen oxide. This is analogous to related compounds such as hydrogen peroxide, hydrogen sulfide, and deuterium oxide (heavy water). Another systematic name, oxidane, is accepted by IUPAC as a parent name for the systematic naming of oxygen-based substituent groups,[23] although even these commonly have other recommended names. For example, the name hydroxyl is recommended over oxidanyl for the –OH group. The name oxane is explicitly mentioned by the IUPAC as being unsuitable for this purpose, since it is already the name of a cyclic ether also known as tetrahydropyran in the Hantzsch-Widman system; similar compounds include dioxane and trioxane.

[edit] Systematic nomenclature
Main article: Dihydrogen monoxide hoax

Dihydrogen monoxide or DHMO is an overly pedantic systematic covalent name of water. This term has been used in parodies of chemical research that call for this "lethal chemical" to be banned. In reality, a more realistic systematic name would be hydrogen oxide, since the "di-" and "mon-" prefixes are superfluous. Hydrogen sulfide, H2S, is never referred to as "dihydrogen monosulfide", and hydrogen peroxide, H2O2, is never called "dihydrogen dioxide"

Thank you Wikipedia.

That still doesn't explain how a molecular compound and an ionic compound are the same.  All it says is that my chemistry book is outdated.

[HTA!]

Are you sure both are considered to be water?
Hydroxide is a polyatomic ion, and the bonding should be different than a normal water molecule.

Maybe they aren't the same and you're mistaken...