Classifying Matter and Separating Techniques

Matter and Chemicals  Matter is anything with mass and occupies space  118 elements in the PT  Properties of matter depend on composition (the atoms), and arrangement (how are they placed within the molecule).  Small changes in composition or structure can DRAMATICALLY change the properties of a molecule. Is energy or radiation considered matter?

Isomer #1 Same formula different structure. Same # of C, H, O but very different in properties Differ in MP, BP, solubility (How it dissolves). BP ethanol = 79 0 C BP dimethyl ether = C (gas, gas, gas!) Ball and Stick Model – accurately shows angles between atoms. Balls are atoms, sticks are bonds.

Isomer #2 (Cis VS Trans) Same formula different arrangement. Same # of elements Differ in MP, BP, solubility (How it dissolves). Cis – the same elements are on one side creating a mirror image. Trans- the same elements are on opposite sides. Ball and Stick Model – accurately shows angles between atoms. Balls are atoms, sticks are bonds.

Classifying Matter Way #1: Gas/Vapor, Liquid, or Gas

Classifying Matter Way #2: element, molecule or mixture A pure substance doesn’t vary from sample to sample. All substances can be elements or compounds. Compounds are substances with two or more different elements (H 2 0) Molecules are any two or more elements. (H 2 ) H 2 0 is both a compound and molecule while H 2 is only a molecule.

Compound, Molecule, Heterogeneous, Homogeneous? Mixtures are a combination of two or more pure substances where each substance keeps its chemical identity. Two types: homogenous (solutions) composed of various substances but are evenly spread out; looks like one thing. Heterogeneous mixtures (suspensions) are unevenly distributed forming layers or spots. ①H 2 SO 4 ②Cl 2 ③Unreactive Xe ④Coffee ⑤Wood ⑥Air Molecule, compound Molecule None (element) Homogeneous Solution Heterogeneous (layers!!!) Homogenous or Solution

Law of Constant Composition Aka law of definite proportion Elements found in a specific compound are always the same. All samples of water will always have 2 H’s and 1O in a 2:1 ratio. For water, 94% of the mass of water and 6% of the mass in hydrogen are the same for any water molecule.

Physical and Chemical Properties PhysicalChemical Are observed w/o changing the identity nor chemical composition. Examples: Color change Odor Density Melting point, boiling point Hardness No bonds are broken, compound and molecules are re-arranged and is usually reversible. Bonds are broken and new bonds are formed to make a new substance. Examples: Rusting Color change Temperature change Formation of precipitate (solid) Usually irreversible.

Separating Mixtures: Paper Chromatography Chromatography: separation of liquid mixture Sample is dissolved in a solvent (liquid or gas) called the mobile phase. Solvent rises due to capillary action and components rise at different rates What can we conclude from the results of this paper chromatography trial? Paracetamol = pain killer Applications: separating colors from dye, separating pigments form colors, separating drugs from blood

Silica gel or alumina is used as a stationary phase Put a mixture into a vertical glass column. Different columns form because one compound may be more polar than the other. The less polar substance spends more time in the solvent and washed through the column faster. Add solvent and elute (remove) each layer. Separating Mixtures: Column Chromatography

Separating Mixtures: Filtration Separation by using a filter resulting a residue and filtrate. Separation by vacuum filtration to separate crystals and liquid. Separate by adding acid resulting in salts and water. Separate based on density using a pipette if there are layers. Separate using a magnet.

Small solid particles in a liquid can pass through a filter paper. For such particles, filtration cannot be used. So, centrifugation is the process of separation of insoluble materials from a liquid. The apparatus used for centrifugation is called a centrifuge. The centrifuge tubes rotate fast, the denser insoluble particles separate from the liquid. The solid particles end up at the bottom with liquid on top. Separating Mixtures: Centrifugation

Simple distillation is used for the separation of a mixture containing two miscible liquids. Distillation involves heating a liquid to its boiling points, and transferring the vapors into the cold portion of the apparatus, then condensing the vapors and collecting the condensed liquid in a container. Separating Mixtures: Simple Distillation Fractional distillation separates more than 2 miscible liquids.