Separation Methods

Types of Solutions & Mixtures Solution: A homogeneous mixture of two or more compounds where a solute has dissolved in a solvent Solution: A homogeneous mixture of two or more compounds where a solute has dissolved in a solvent Homogeneous: A mixture that is perfectly uniform throughout, that is the same throughout Homogeneous: A mixture that is perfectly uniform throughout, that is the same throughout

Mixture: A combination of two or more substances that are mixed together but not chemically combined. Mixtures can be either homogeneous or heterogeneous Mixture: A combination of two or more substances that are mixed together but not chemically combined. Mixtures can be either homogeneous or heterogeneous Heterogeneous: A mixture of substances that is not the same through out or not uniform Heterogeneous: A mixture of substances that is not the same through out or not uniform

Examples: Homogeneous or Heterogeneous += += Homogeneous Heterogeneous

+ = += Homogeneous Heterogeneous ++ ++

Examples Heterogeneous Homogeneous

Separating Mixtures Decanting Decanting Definition: A method of separation in which a solution is poured from a container in order to leave the precipitate at the bottom of the original container Definition: A method of separation in which a solution is poured from a container in order to leave the precipitate at the bottom of the original container When to use: When there is presence of a precipitate that is of much greater density than the solution When to use: When there is presence of a precipitate that is of much greater density than the solution

Decanting (cont.) Decanting (cont.) Accuracy: Poor/Rough- usually a small amount of solution is left behind, usually used as a first step in separation Accuracy: Poor/Rough- usually a small amount of solution is left behind, usually used as a first step in separation

Sedimentation Sedimentation Definition: The settling of Definition: The settling of particles that are suspended in a liquid, usually due to gravity When to use it: When time is not a concern (this is a slow process), when only a top layer of something is needed When to use it: When time is not a concern (this is a slow process), when only a top layer of something is needed Accuracy: Poor- for the time it takes it does not produce ideal results. This is however a common separation technique found in nature Accuracy: Poor- for the time it takes it does not produce ideal results. This is however a common separation technique found in nature

Filtering Filtering Definition: A separation technique using a filter to: Definition: A separation technique using a filter to: remove particles that are suspended in a solution remove particles that are suspended in a solution physically block certain substances from passing through while allowing others to pass easily (e.g. a coffee filter) physically block certain substances from passing through while allowing others to pass easily (e.g. a coffee filter) The liquid resulting after a filtration is called the filtrate The liquid resulting after a filtration is called the filtrate

Filtering (cont.) Filtering (cont.) When to Use: When to Use: When a solid is present in a solution but is too fine, small or not a higher density than the liquid to allow for decanting. When a solid is present in a solution but is too fine, small or not a higher density than the liquid to allow for decanting. These solutions usually are cloudy in appearance. These solutions usually are cloudy in appearance. Accuracy: Accuracy: Medium- Very successful in removing fine solid particulates from liquid (or gaseous) mediums but some liquid stays with the particles on the filter Medium- Very successful in removing fine solid particulates from liquid (or gaseous) mediums but some liquid stays with the particles on the filter Some particles may also pass through the filter depending on its thickness/pore size Some particles may also pass through the filter depending on its thickness/pore size

Distillation: Distillation: Definition: A separation method that separates homogeneous mixtures by using the difference in boiling points of the different parts. Definition: A separation method that separates homogeneous mixtures by using the difference in boiling points of the different parts. As the component with the lowest density begins to boil first, the resulting gas can be collected, cooled, condensed and the separated liquid collected.

Distillation (cont.) Distillation (cont.) When to Use: When to Use: When a solution has little to no visible particulates When a solution has little to no visible particulates When the presence of micro-organisms is suspected When the presence of micro-organisms is suspected When there is a need to separate two liquids in solution When there is a need to separate two liquids in solution Accuracy: Good- Since you are boiling the solution you are killing micro-organisms as well as removing dissolved solids, and separating liquids with different boiling points Accuracy: Good- Since you are boiling the solution you are killing micro-organisms as well as removing dissolved solids, and separating liquids with different boiling points