Video Transcript
Which of the following is true for
mixtures? (A) Mixtures can only be made by mixing
pure substances together. (B) A mixture is always formed when two
substances react together. (C) Pure elements cannot form
mixtures. (D) Mixtures cannot be separated into
their components. Or (E) mixtures consists of particles of
different substances mixed but not reacted together.
We can see in statement A that we can’t
make a mixture by mixing pure substances together, like nitrogen gas and oxygen gas. But there’s nothing stopping us mixing
another gas with that mixture to produce a new mixture. The next statement suggests that a
mixture is always formed when two substances react together. However, if, for instance, we react
carbon and oxygen gas together in a ratio of one carbon atom to one oxygen molecule, we’ll
produce carbon dioxide in its pure form. So we won’t generate a mixture there. We know from mixing nitrogen and oxygen
together that pure elements can form mixtures, so the next statement is false.
The next statement says that mixtures
cannot be separated into their components. But if we have a sample of iron filings
mixed with sulfur, we can use a magnet to pull out the iron filings, separating the mixture,
which just leaves us with a definition of mixtures. Mixtures consist of particles of
different substances mixed but not reacted together.
