Chromium(II) oxide

{{chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 451184087

| ImageFile = NaCl polyhedra.png

| IUPACName = chromium(II) oxide

| OtherNames =

|Section1={{Chembox Identifiers

| CASNo_Ref = {{cascite|correct|??}}

| CASNo = 12018-00-7

| ChemSpiderID = 2300900

| PubChem = 3037052

| StdInChI=1S/Cr.O

| StdInChIKey = XVOFZWCCFLVFRR-UHFFFAOYSA-N

| SMILES = O=[Cr]

}}

|Section2={{Chembox Properties

| Formula = CrO

| MolarMass = 67.996 g/mol

| Appearance = black

| Density =

| MeltingPtC = 300

| MeltingPt_notes = (decomposes)

| BoilingPt =

| Solubility = }}

|Section3={{Chembox Structure

| CrystalStruct = cubic, cF8

| SpaceGroup = Fm3m, No. 225

}}

}}

Chromium(II) oxide (CrO) is an inorganic compound composed of chromium and oxygen.{{citation|title=Dictionary of Inorganic Chemistry |author=Satish. Anand, Raj. Kumar|year=1989|publisher=Anmol Publications |url= https://books.google.com/books?id=6yDA6nb5KCUC&dq=%22Chromium(II)+oxide%22&pg=PA65|isbn=978-81-7041-236-6}} It is a black powder that crystallises in the rock salt structure.Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier {{ISBN|0-12-352651-5}}

Hypophosphites may reduce chromium(III) oxide to chromium(II) oxide:

:H₃PO₂ + 2 Cr₂O₃ → 4 CrO + H₃PO₄

It is readily oxidized by the atmosphere. CrO is basic, while {{chem2|CrO3}} is acidic, and {{chem2|Cr2O3}} is amphoteric.Chemistry 7th edition, by Raymond Chang page 645 (problem 15.100)

CrO occurs in the spectra of luminous red novae, which occur when two stars collide. It is not known why red novae are the only objects that feature this molecule; one possible explanation is an as-yet-unknown nucleosynthesis process.{{cite journal|bibcode=2015A&A...580A..34K|arxiv=1504.03421|title=Post-outburst spectra of a stellar-merger remnant of V1309 Scorpii: From a twin of V838 Monocerotis to a clone of V4332 Sagittarii|journal=Astronomy & Astrophysics|volume=580|pages=A34|last1=Kamiński|first1=T.|last2=Mason|first2=E.|last3=Tylenda|first3=R.|last4=Schmidt|first4=M. R.|year=2015|doi=10.1051/0004-6361/201526212|s2cid=118566357}}