via the Bioportal I found:

In the "Units of measurement ontology" http://bioportal.bioontology.org/ontologies/45830 : http://www.berkeleybop.org/ontologies/owl/UO#UO_0000062

  <owl:Class rdf:about="&lt;a href=" http:="" purl.org="" obo="" owl="" UO#UO_0000062"="" rel="nofollow">http://purl.org/obo/owl/UO#UO_0000062">
    <rdfs:label xml:lang="en">molar</rdfs:label>
    <oboInOwl:inSubset rdf:resource="&lt;a href=" http:="" purl.org="" obo="" owl="" obo#unit_slim"="" rel="nofollow">http://purl.org/obo/owl/obo#unit_slim"/>
    <oboInOwl:hasDefinition>
      <oboInOwl:Definition>
        <rdfs:label xml:lang="en">A unit of concentration which expresses a concentration of 1 mole of solute per liter of solution (mol/L).</rdfs:label>
        <oboInOwl:hasDbXref>
          <oboInOwl:DbXref>
            <rdfs:label>UOC:GVG</rdfs:label>
            <oboInOwl:hasURI rdf:datatype="&lt;a href=" http:="" www.w3.org="" 2001="" XMLSchema#anyURI"="" rel="nofollow">http://www.w3.org/2001/XMLSchema#anyURI">http://purl.org/obo/owl/UOC#UOC_GVG</oboInOwl:hasURI>
          </oboInOwl:DbXref>
        </oboInOwl:hasDbXref>
      </oboInOwl:Definition>
    </oboInOwl:hasDefinition>
    <oboInOwl:hasExactSynonym>
      <oboInOwl:Synonym>
        <rdfs:label xml:lang="en">M</rdfs:label>
      </oboInOwl:Synonym>
    </oboInOwl:hasExactSynonym>
    <oboInOwl:hasOBONamespace>unit.ontology</oboInOwl:hasOBONamespace>
    <rdfs:subClassOf rdf:resource="&lt;a href=" http:="" purl.org="" obo="" owl="" UO#UO_0000061"="" rel="nofollow">http://purl.org/obo/owl/UO#UO_0000061"/>
  </owl:Class>

QUDT

unit:MolePerCubicMeter
  rdf:type qudt:MolarConcentrationUnit , qudt:SIDerivedUnit ;
  rdfs:label "Mole per Cubic Meter"^^xsd:string ;
  qudt:abbreviation "mol/m^3"^^xsd:string ;
  qudt:code "1220"^^xsd:string ;
  qudt:conversionMultiplier
          1.0e0 ;
  qudt:conversionOffset
          "0.0"^^xsd:double ;
  qudt:symbol "mol/m^3"^^xsd:string .