Solids Mix at High Temperatures

A SMALL AMOUNT OF OIL DISSOLVED IN WATER. Test tube 1 has a very small amount of oil in a large volume of w ater. The oil fully dissolves in the 

An oil phase on top of a water phase. Test tube 3 has a higher oil concentration than tube 2. As a result, test tube 3 has a larger volume of the oil phase and a smaller volume of the water phase. This is a two-phase solution. The top phase is not pure oil and the bottom phase is not pure water. Rather, the water-rich phase on the bottom is saturated with oil, having oil concentration x. The oil-rich phase on top is saturated with water, having oil concentration x . 

The oil phase on top of the water phase, but more of it. Test tube 4 continues the trend of higher oil/water ratios. Tube 4 has a larger volume of the oil-rich phase than tube 3, and a smaller volume of the water-rich phase. But the compositions of the oil-rich and water-rich phases remain the same as they are in test tube 3 the bottom phase still has oil concentration x, and the top phase still has oil concentration x . 

A SMALL AMOUNT OF WATER DISSOLVED IN OIL. Test tube 6 Contains a single phase, in which a ery small amount of water is fully dissolved in a large amount of oil. 

Solutions 2 and 5 each define a point on the phase boundary, also called the solubility curve or coexistence curve. A phase is a region in which the composition and properties are uniform. Inside the phase boundary is the coexistence region where two phases are in equilibrium an oil-rich phase sits on a water-rich phase (as in test tubes 3 and 4). Outside the phase boundary, you have a one-phase solution, either oil dissolved in water or water dissolved in oil (test tubes 1 and 6). From the six experiments at temperature T = To, two compositions, x and x , define the phase boundary. 

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