Those Irritating “In-Between” Mixtures

Some mixtures are difficult to classify as heterogeneous or homogeneous. Example: OJ – may look like a homogenous mixture = solution

However, the natural fruit sediment will eventually settle out (slowly) Ex. Old roommate Joseph who would let his OJ sit in the fridge for months! However….

Actually, OJ is a heterogeneous mixture where particles settle slowly after mixing = suspension Other examples = Italian salad dressing or clay in water

Another difficult example (whether you knew it or not) is milk! The homogenization process used in making milk helps keep the fat globules in the milk

If the particles in a suspension don’t settle much the mixture is called a colloid.

A further example is mayonnaise Mayo is a colloid where particles can be dispersed for even longer by adding an emulsifying agent This mixture is called an emulsion

What about pop? Looks like a single substance, but… It actually has two obvious and distinct parts (the syrup and the gas) = a mechanical mixture (heterogeneous)

Each of the parts in a mechanical mixture are called phases