Separating Sand From Sugar

SEPARATING MIXTURES Mixtures are Physically combined. Thus Mixtures can be Physically separated. Separation techniques are based on different physical properties that the materials in the mixture have. These properties include: Boiling Point, Solubility, Density, Attractive Forces, as well as, other common physical properties. 1. Filtration: This separation technique is based on the property of Solubility. This process allows the separation of a soluble substance from an insoluble substance. EXAMPLE: Separating sand from sugar. a) In this mixture the sand is insoluble and the sugar is soluble b) If you have some sand and sugar in a beaker what is the first step that needs to be done? Add water and stir until the sugar 1 dissolves. Sand will NOT dissolve   c) What type of mixture is now in the beaker? Heterogeneous Mixture d) Complete the labels in the diagram below. [Diagram of a filtration setup with labels:] Liquid and insoluble solid Filter paper Filter funnel Filtered solid - Sand - insoluble Filtered liquid - filtrate Salt + H₂O (soluble) Homogeneous Mixture e) What type of mixture is the liquid filtrate left in the flask? Homo Mix f) What needs to be done in order to separate the salt left in the flask? Evaporate off the water and the salt will remain. 2. Chromatography This separation technique is based on the abilities of substances to be attracted to various solids such as paper or starch. This is dependant on the substances differences in attractive forces and it's solubility.   EXAMPLE 1: Separating the different colors of ink. a) Ink is placed at the bottom of a piece of filter or chromatography paper. b) The paper is placed in a beaker or test tube so the bottom of the paper touches the solvent, water or alcohol. c) The different colors of ink will travel up the paper based on their attraction for the paper. d) In the Figure below which color of ink will have the most attraction for the paper? The one that has moved up the paper the most or the one that is still close to the bottom?   The top has the greatest attraction for the paper. [Diagram of a chromatography setup with labels:] Most Attraction! Water Soluble ink Permanent ink Least Attraction Is soluble in alcohol EXAMPLE 2: Separating the components found in a green leafy plant. a) The different pigments in a plant can also be separated by chromatography. b) The difference is the solvent you use to separate the pigments. c) Some inks and pigments are water soluble, some are not!   [Diagram of a chromatography setup for plant pigments with labels:] solvent front carotendids xanthophylls chlorophyll a chlorophyll b leaf extract different solvent 3. Distillation: This separation technique is based on the property of Different Boiling Points. It is generally used to separate a mixture of different liquids. The liquid with the Lower Boiling Point in a mixture will vaporize first and travel through the condensing tube and condense back into a liquid in a separate flask. EXAMPLE 1: This process can also be used to obtain pure water from sea water (salt water). Give a reason for why you would want to separate pure water from sea water. 1   To be used for drinking water. [Diagram of a distillation setup with labels:] Thermometer Water out Condenser Flask Boiling liquid Water in Distillate (pure water) Heat from Bunsen Burner Wooden block a) Given the distillation set up above, what begins happening in the heated flask at 100°C? Water starts to boil and become vapor b) Where does this water vapor go? Into the Condensing tube c) Cool water circulates around the inner tube of the condenser. Why is this required? To cool the vapor and change it to liquid. EXAMPLE 2: Separating alcohol from water. a) Heat a solution of alcohol and water. b) Alcohol has a lower boiling point than water so it will boil and vaporize first c) The Alcohol vapor travels through the condensing tube and cools. d) The pure Alcohol drips into the receiving flask and pure Water remains in the original flask.