Is it right to say this on a biology paper

i am trying to explain the factors that affect the rate of diffusion.. i got temperature, surface area, how large the drop of chemical is (concentration gradient) and whether or not the substances are "mixable"
but "mixable" doesn't sound like a term i would find in my biology book.. so i think my teacher would want another way to describe this.. for example, oil and water is not as mixable, as salt and water

The correct word is miscible not mixable. They mean the same thing except mixable isn't a word.

Perhaps the terms "miscible" and "immiscible". Basically, mixable/not mixable.