Substance is generally defined as a physical matter or material so the answer to your question would be yes.
kool-aid is a mixture while water is a compund.
it dossolves into the water and mix with sugar
Well "Kool" is a variation of "Cool" and it was made with the intention of creating a cool, refreshing drink. So, it's just a creative variation of "Cool Aid" : Kool-Aid http://koolaidlovers.com