ORGANIC LAB ENDTERM

• Chemical Properties - describe the characteristic ability of a substance to react to form new substances; they include its flammability and susceptibility to corrosion.
• Physical Properties - characteristics that scientists can measure without changing the composition of the sample under study, such as mass, color, and volume (the amount of space occupied by a sample).
• TYPES OF PHYSICAL PROPERTIES

  1. Extensive properties
  2. Intensive properties
• Extensive properties

  • vary with the amount of the substance.
• Intensive properties

  • in contrast, do not depend on the amount of the substance.
• Physical changes

  • are changes in which no chemical bonds are broken or formed.
  • This means that the same types of compounds or elements that were there at the beginning of the change are there at the end of the change.
• Melting Point

  • The temperature where the solid-liquid phase change occurs.
• Melting Point Since this requires that the intermolecular forces that hold the solid together have to be overcome, the temperature at which melting occurs will depend on the structure of the molecule involved - an example of the relationship between structure and properties.
• Thiele tube

  • is a glass tube designed to contain heating oil and a thermometer to which a capillary tube containing the sample is attached.
• Boiling Point

  • is reached when the total vapor pressure of the liquid is equivalent to the atmospheric pressure.
• Vapor pressure

  • is a measure of the tendency of a material to change into the gaseous or vapor state, and it increases with temperature. The temperature at which the vapor pressure at the surface of a liquid becomes equal to the pressure exerted by the surroundings is called the boiling point of the liquid.
• Atmospheric pressure

  • The air around you has weight, and it presses against everything it touches. That pressure is called atmospheric pressure, or air pressure.
• Chromatography

  -is the technique for the separation, purification, and testing of compounds.
• Chromatography is works on the principle of differential partitioning between

  1. mobile phase (like a liquid or gas)
  2. stationary phase (like a solid or a liquid absorbed onto a solid).
• Types of chromatography

  1. Adsorption Chromatography
  2. Thin Layer Chromatography
  3. Column Chromatography
  4. Partition Chromatography
• ascending type or radial paper chromatography

  type of chromatography that is easy to perform
• Selecting a suitable filter paper: Selection of filter paper is done based on the size of the pores and the sample quality.
• Types of paper chromatography:

  1. Ascending Paper Chromatography
  2. Descending Paper Chromatography
  3. Radial or Circular Paper Chromatography
  4. Two-Dimensional Paper Chromatography
• Ascending Paper Chromatography – The technique goes with its name as the solvent moves in an upward direction.
• Descending Paper Chromatography – The movement of the flow of solvent due to gravitational pull and capillary action is downwards, hence the name descending paper chromatography.
• Radial or Circular Paper Chromatography – The sample is deposited at the center of the circular filter paper. Once the spot is dried, the filter paper is tied horizontally on a Petri dish that contains the solvent.
• Two-Dimensional Paper Chromatography – Substances which have the same rf values can be resolved with the help of two-dimensional paper chromatography.