The big picture
Size of the pieces explains most of this chapter.
| Idea | Remember | Example |
|---|---|---|
| Same all through, or not | A mixture is homogeneous when it is the same all through. It is heterogeneous when its parts are not the same everywhere. | Vinegar is homogeneous. Oil and water is not. |
| Solution, colloid, suspension | A solution has the smallest pieces and a suspension has the largest. A colloid lies in between. Size decides what the tests show. | Salt water, milk, muddy water |
| Light through a mixture | Light scatters off the pieces in a colloid or a suspension. A true solution hardly scatters light. This scattering is the Tyndall effect. | Dust shows in a beam of light. |
| How strong is a solution | Concentration tells how much solute is in the whole solution. Mass by mass percentage is solute mass ÷ solution mass × 100. | 12 g in 100 g is 12 % |
| Picking a method | Each method works on a property in which the parts differ. If the parts do not differ in it, the method fails. | Sublimation takes camphor out of sand. |
| Getting back what dissolved | For most solids, a hot saturated solution holds less when it cools. The extra solute comes out as crystals. | Potassium nitrate gives about 106 g, salt about 2 g. |
| More than two parts | Each part needs its own step. The step uses a property that sets the part apart. Do each step only while its property still works. A later step must not undo an earlier one. | Heat first, then water, filter, boil. |
Chapter 5 of your book, Exploration, is Exploring Mixtures and their Separation. Read the chapter this week, with these seven ideas beside you.