ANACHEM LAB

• Alkali is a base in aqueous solution that can turn red litmus paper to blue
• Reagents are solids or solutions of known substances used to identify or help identify unknown substances
• Test solutions are very dilute solutions used to demonstrate the chemical behavior of a given constituent towards certain reagents
• Colloidal Suspension is a mixture with particles of one component suspended in a continuous phase of another component, with diameters between 10^-7 and 10^-9 meters
• True Solution or Solution is a homogeneous mixture of two or more substances in a single phase, containing a solute and a solvent

  • It is a mixture because it contains two or more substances in proportions that can be varied
  • It is homogeneous because its composition and properties are uniform
• Supernatant liquid or Supernatant is the clear liquid above a sediment, suspension, or precipitate
• Decantation is a method for mechanical dewatering of a wet solid by pouring off the liquid part without disturbing underlying sediments or precipitate
• Dilution is preparing a solution by adding more solvent to an existing solution without changing the number of moles of solute
• Extraction is the process of obtaining something from a mixture or compound by chemical, physical, or mechanical means
• Evaporation is the process of removing or reducing the liquid component of a mixture by heating the mixture over an open flame
• Filtration is the process of separating solid particles from a liquid by pouring the mixture through a filter medium
• Neutralization is the process of making a solution neutral (pH = 7) by adding a base to an acidic solution or an acid to a basic solution
• Precipitation is the formation of a suspension of an insoluble compound by mixing two solutions
• Titration is the controlled addition and measurement of the amount of a solution of known concentration required to react completely with a measured amount of a solution of unknown concentration
• Volatile is a substance capable of readily changing from a solid or liquid form to a vapor, having a high vapor pressure and a low boiling point
• Separations. These are procedures that separate groups of ions from other groups, or individual ions in a mixture of ions.
• Confirmatory tests. These are tests that determine conclusively that a certain ion is present. Interfering ions are removed before a confirmatory test is done.
• Precipitation.

  When we place half ml of a solution of sodium hydroxide in a test tube and slowly add to this half ml of ferric chloride solution.

  Give the balanced chemical equation for this reaction.

  FeCl+ 3 NaOH = Fe(OH)3 + 3 NaCl

  What is the name of the precipitate that was formed?

  Ferric Chloride

  What is the name of the supernatant liquid?

  Sodium hydroxide by adding more Ferric chloride
• The centrifuge

  Put the test tube with the solution from procedure 1 in a centrifuge and centrifuge for 1-2 minutes.

  What is the purpose of placing an qual volume of water?

  To balance and prevent wobbling

  Describe the result after centrifugation.

  hardent/soldified

  What is the function of the centrifuge?

  To divide suspended particles in a liquid
• C. Removal of Supernatant Liquid

  What proper precaution is needed in removing the liquid portion?

  extraction
• D. Washing of Precipitate

  After removal of the centrifugate, the precipitate remaining in the test tube is wet with the solution containing the ions of the centrifugate. These ions may cause interference in the analysis of the precipitate and are usually removed by _

  • CenfriFugation
• What is the purpose of washing the precipitate?

  helps remove any ions
• Heating in Water Bath

  Fill the beaker with 2/3 water and this serves as a water bath. Place 10 drops of lead nitrate in a test tube and 4 drops of 3M HCl. Add 6-7 drops water and heat in a water bath.

  Describe the results

  small bubble begin and precipitation of lead chloride and sodium nitrate is formed. A cloudy white appearance
• Evaporation

  Put 10 drops of sodium chloride solution in a watch glass or evaporating dish. Put the watch glass or evaporating dish on the water bath. Heat the water bath to boiling until all the water in the watch glass or evaporating dish has completely evaporated. Examine the watch glass or evaporating dish and observe for the presence of a residue.

  Result:

  impurities settled out and white crystallized residue and forms salt