Now we are going to learn very common in industry process, which is called extraction.
Grind a few kernels of walnuts and a handful of sunflower seeds (of course, without husk), put in a test tube and pour the gasoline. Next there should be fire - gasoline can catch fire!
Shake the test tube and let it stand two hours, not forgetting from time to time to shake things up. Then drain the solution on a plate and set on draught. When gasoline evaporates, you will see at the bottom a little oil. So with the help of petrol you have learned (was extracted) oil from seeds. This happened due to the fact that the oil is soluble in gasoline.
Can try to prepare oil from other seeds. Just don't try it for the taste!
Another experience with leaves. For it we will need a water bath and a glass with thin walls (if they are thick, the glass, as you remember, can burst). Fresh leaf of some plants put in a vessel and pour a small amount of diluted alcohol. Heat the water in the bath, remove from heat and place inside a glass sheet. Some time later, tweezers, remove the piece: he bleached and alcohol became emerald color. So you spent the extraction of chlorophyll - the green pigment of plants.
By the way, if you take obviously edible plant lettuce or spinach, it this way, you can extract food coloring to coloring cream or sauce. So come on food plants: edible green dye is removed by extraction from the leaves. To speed up this process, I encourage you chop the leaves and shake from time to time the vessel.
Another experience. In a test tube half filled with water, add about 1 ml of drugstore tincture of iodine; get brownish solution. Add to it an equal amount of gasoline, shake several times and leave the rest. When the mixture will exfoliate, it will appear that the upper, gasoline layer was dark brown, and the lower, aqueous layer was almost colorless. Iodine dissolved in water is bad, and gasoline - well. That's why he's from aqueous solution was passed into gasoline.
On the difference in solubility based our recent experience with extraction. How to quickly distinguish the coffee powder from the powder of chicory? By smell, that's understandable, but if the smell is weak or you don't remember exactly? Then throw a pinch of the powder in a transparent vessel with hot water. Colored substances chicory difficult extracted with water, so it will remain practically colorless. And substances of coffee, by contrast, is easily dissolved in water, and the powder slowly sinks to the bottom, leaving a brown trail.