CHEM 101 Study Guide - Midterm Guide: Chemical Energy, Boiling Point, Kelvin
Document Summary
The nitrogen in air has all the properties of pure nitrogen because both the pure substance and the mixture contain the same nitrogen molecules. ) Physical change: a substance changes its physical appearance but not its composition same substance before and after, all changes of state are physical changes. Chemical change: = chemical reaction, a substance is transformed into a chemically different substance (when hydrogen burns in air it undergoes a chemical change because it combines with oxygen) Thus, if we put our mixture into an appropriate acid, the acid would dissolve the iron and the solid gold would be left behind. The two could then be separated filtration: distillation: important method of separating the components of a homogeneous mixture; depends on the different abilities of substances to form gases. For example, if we boil a solution of salt and water, the water evaporates, forming a gas, and the salt is left behind.
