Water appears as a clear, nontoxic liquid composed of hydrogen and oxygen, essential for life and the most widely used solvent. Include water in a mixture to learn how it could react with other chemicals in the mixture. Water is an oxygen hydride consisting of an oxygen atom that is covalently bonded to two hydrogen atoms. It has a role as an amphiprotic solvent, a member of greenhouse gas, a human metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite and a mouse metabolite. It is an oxygen hydride, a mononuclear parent hydride and an inorganic hydroxy compound. It is a conjugate base of an oxonium. It is a conjugate acid of a hydroxide.