CHEMICAL ANAYLSIS

• what is a pure substance?


  a single element or compound, not mixed with any other substances
• what do impurities do to the melting points and boiling points of a substance?


  they decrease the melting point and increase the boiling point
• what is a formulation?


  a mixture that has been designed as a useful product
• what are some examples of formulations?

  - fuels

  - cleaning agents

  - paints

  - medicines

  - alloys

  - fertilizers

  - food
• what is chromatography?


  an analytical method used to separate the substances in a mixture
• what are the two phases in chromatography?

  mobile and stationary
• what happens in the mobile phase of chromatography?

  the molecules can move as a liquid or a gas
• what happens in the stationary phase of chromatography?

  the molecules can't move as a solid or a very thick liquid
• what are the phases in paper chromatography?

  the stationary phase is the chromatography paper and the mobile is the solvent
• what is the Rf value?

  rf = distance moved by substance / distance moved by solvent

  
• what is the test for hydrogen?


  a burning splint which burns rapidly with a pop in hydrogen
• what is the test for oxygen?


  a glowing splint which relights in oxygen
• what is the test for carbon dioxide?


  carbon dioxide is bubbled or shaken into limewater, which turns milky/cloudy
• what is the test for chlorine?


  litmus paper which turns white in chlorine gas
• what are ways to identify metal ions?

  - flame tests

  - sodium hydroxide solution

  - flame emission spectroscopy
• what is the flame test for lithium compounds?


  a crimson flame
• what is the flame test for sodium compounds?


  a yellow flame
• what is the flame test for potassium compounds?


  a lilac flame
• what is the flame test for calcium compounds?


  an orange-red flame
• what is the flame test for copper compounds?


  a green flame
• what is the sodium hydroxide test for calcium?


  a white precipitate
• what is the sodium hydroxide test for magnesium?


  a white precipitate
• what is the sodium hydroxide test for aluminum?


  a white precipitate at first, then colorless (dissolves in excess solution)
• what is the sodium hydroxide test for copper(II)?


  a blue precipitate
• what is the sodium hydroxide test for iron(II)?


  a green precipitate
• what is the sodium hydroxide test for iron(III)?


  a brown precipitate
• what is the test for carbonates?


  carbonates react with dilute acids to form carbon dioxide gas; carbon dioxide can be identified with limewater
• how are halides identified?


  using silver nitrate solution in the presence of dilute nitric acid
• what is the test for (silver) chloride?


  with silver nitrate and nitric acid to form a white precipitate
• what is the test for (silver) bromide?


  with silver nitrate and nitric acid to form a cream precipitate
• what is the test for (silver) iodide?


  with silver nitrate and nitric acid to form a yellow precipitate
• what is the test for sulfates?

  sulfate ions produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid
• what are the advantages of instrumental methods?

  - accurate

  - sensitive

  - rapid
• what is flame emission spectroscopy?

  an instrumental method using a spectroscope and identifying line spectrums
• what is flame emission spectroscopy used for?

  to analyze metal ions in solutions
• Pure substance

  A single element or compound, not mixed with any other substance
• Formulation

  A mixture of compounds in measured quantities that has been designed as a useful product
• Paper chromatography

  1. Draw start line

  2. Place sample on line

  3. Fill beaker with solvent

  4. Hang paper in beaker

  5. Solvent travels up paper

  6. Mark finish line

  7. Dry paper
• Rf value

  Distance moved by the spot / distance moved by solvent
• Rf value of 0.85

  Compound has higher affinity for the solvent than for the paper