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Solutions: Mixtures, Solubility and Concentration
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The infamous saltwater crocodile cannot survive in freshwater. It needs a mixture of water and many solutes.
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Mixtures vs. Pure Substances
Mixtures contain two or more pure substances. Mixtures do not
- bey the law of definite composition therefore the relative
amounts of each substance can vary depending on the sample. Pure water Salt water H2O contains H2O, Ca2+, Cl-, Na+..... 89% O, 11% H composition by mass varies chemical separation method physical All mixtures can be separated using physical means while most pure substances cannot with the exception of thermal decomposition of certain pure substances such as metal carbonates and metal chlorates. What are some methods for physically separating mixtures?
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Mixtures
Mixtures are classified as suspensions, colloids, or solutions based on particle size. Suspension Colloid Solution Particle Size
> 1000 nm 1000 nm <-->1 nm
< 1 nm Settling Yes No No Homogenous No Yes
Yes
Tyndall Effect (particles scatter light) Yes Yes No Given the similarity between colloids and solutions, the Tyndall effect is often key to distinguishing them apart. Click here to see a short animation of the Tyndall Effect