VOLUME
Again, suppose we’re thinking about a sample of matter—solid, liquid, or gas.
When we say volume, we’re talking about how much room the sample takes up
in space. The SAT Chemistry Subject Test usually measures volume in liters (L)
or milliliters (mL; 1 mL = 1/1,000 L—also keep in mind that 1 mL = 1 cm^3 , or
cubic centimeter).
How a sample is measured depends on what state it’s in—whether it is a solid,
liquid, or gas. When the sample is a liquid, we can determine its volume by
pouring it into a graduated cylinder or any other measuring flask.
If the sample is a solid, we can immerse it in a liquid and see how much liquid it
displaces. In other words, we can compare the original volume of the liquid and
the volume of the solid/liquid combination, knowing that the difference will be
equal to the volume of the solid.
For samples of gas, the volume of the gas is always equal to the volume of its
container, since a gas always expands to fill its container. How do we learn the
volume of the container? Well, if the volume isn’t marked on the container, we
can just treat the container as a solid object and find out its volume by
immersing it in a liquid.