To a first approximation, oil and water don't mix,
Or, even better:
You can get oil to float on top of water. The mass density of oil is less than that of water, and if you don't stir things up you don't need to worry too much about the oil dissolving into the water or vice versa.
Rationale:
The solubility of oil in water (and vice versa) is not infinite ... but it's a long way from zero. This is a major problem if you're interested in clean water and/or clean oil.
BP managed to dissolve a _lot_ of oil into the Gulf of Mexico.
Water dissolved in fuel oil is a nasty problem, partly because it tends to come out of solution when the temperature changes. Water in lubricating oil is no fun either.
In the U-tube experiment in particular, in principle the oil will dissolve in the water, diffuse to the other side, and then come out of solution ... continuing until in equilibrium you have the same depth of oil on both sides. The process is slow, but that has more to do with kinetics than with solubility per se.
If you want to emphasize the distinction between dissolving and mixing, it is easy to mix oil with a comparable quantity of water. Example: salad dressing. If you do it right, with maybe a little sugar and a little mustard, you get an emulsion that will stay mixed for a week or more.
In section 18.6 on page 489 it says:
It would be better to say:
Or, even better:
The solubility of oil in water (and vice versa) is not infinite ... but it's a long way from zero. This is a major problem if you're interested in clean water and/or clean oil.
BP managed to dissolve a _lot_ of oil into the Gulf of Mexico.
Water dissolved in fuel oil is a nasty problem, partly because it tends to come out of solution when the temperature changes. Water in lubricating oil is no fun either.
In the U-tube experiment in particular, in principle the oil will dissolve in the water, diffuse to the other side, and then come out of solution ... continuing until in equilibrium you have the same depth of oil on both sides. The process is slow, but that has more to do with kinetics than with solubility per se.
If you want to emphasize the distinction between dissolving and mixing, it is easy to mix oil with a comparable quantity of water. Example: salad dressing. If you do it right, with maybe a little sugar and a little mustard, you get an emulsion that will stay mixed for a week or more.