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Brainteaser 8/21/12 Homogenous or heterogeneous?? If you have to use a microscope in order to see the different substances in a mixture, that mixture is _____________. Apple juice, salt water, and soda are all examples of a _____________ mixture. These types of mixtures are also known as _____________. Separation Techniques 1 Separating Mixtures ✦ Most matter exists naturally as mixtures. ✦ Because the substances in a mixture are physically combined, the processes used to separate a mixture are physical processes that are based on the difference in physical properties of the substances. ✦ Sometimes it is very easy to separate a mixture; separating a mixture of pennies and nickels is not a difficult task. Separating Mixtures ✦ Heterogeneous mixtures composed of solids and liquids are easily separated by filtration. ✦ Filtration is a technique that uses a porous barrier to separate a solid from a liquid. 2 Separating Mixtures ✦ Most homogeneous mixtures can be separated by distillation ✦ Distillation is a separation technique that is based on differences in the boiling points of the substances involved. Separating Mixtures ✦ When precisely controlled, distillation can separate substances having boiling points that differ by only a few degrees. 3 Separating Mixtures ✦ Crystallization is a separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance. Separating Mixtures ✦ Chromatography is a technique that separates the components of a mixture (called the mobile phase) on the basis of the tendency of each to travel or be drawn across the surface of another material (called the stationary phase). ✦ The separation occurs because the various components of the ink spread through the paper ant different rates. 4 Separating Mixtures Separating Compounds ✦ Only separation technique that is used for compounds ✦ This is a CHEMICAL separation techniques ✦ Electrolysis is the passage of a direct electric current through an ion-containing solution ✦ In the picture, water is being separated into hydrogen and oxygen gas 5