Editing Anhydrous (section)

==Gases==
Several substances that exist as gases at [[standard conditions of temperature and pressure]] are commonly used as concentrated [[aqueous solution]]s. To clarify that it is the gaseous form that is being referred to, the term ''anhydrous'' is prefixed to the name of the substance:
*Gaseous [[ammonia]] is generally referred to as ''anhydrous'' ammonia, to distinguish it from its solution in water, household [[ammonia solution]], also known as ammonium hydroxide.
*Gaseous [[hydrogen chloride]] is generally referred to as ''anhydrous'', to distinguish it from its solution in water, [[hydrochloric acid]].

Reactions which produce water can be kept dry using a [[Dean–Stark apparatus]].