Qualitative and Quantitative Analysis

• How many protons, electrons, and neutrons are in a phosphorus atom?

  15 protons, 15 electrons, and 16 neutrons
• How many protons, electrons, and neutrons are in a phosphide ion?

  15 protons, 18 electrons, and 16 neutrons
• Why do giant ionic structures conduct electricity as a liquid but not as a solid?

  In liquid form, ions are free to move, allowing conductivity, while in solid form, ions are fixed in place.
• Why does carbon dioxide have a low boiling point?

  Carbon dioxide has weak intermolecular forces, which require less energy to overcome.
• What are the advantages of instrumental methods of analysis?

  • Improved sensitivity
  • Increased accuracy
  • Faster testing speed
• How can data from a flame photometer be used to determine the concentration of ions in a dilute solution?

  By using a calibration curve to evaluate the data.
• How can you determine the positive ion in a salt using flame test results?

  By observing the flame color produced during the test.
• What are the flame colors for the following cations: Lithium, Sodium, Potassium, Calcium, and Copper?

  • Lithium: Red
  • Sodium: Yellow
  • Potassium: Lilac
  • Calcium: Orange-red
  • Copper: Blue-green
• What is the procedure for conducting a flame test?

  Wash the loop in acid, dip it into the sample salt, and place it into a blue flame of a Bunsen burner.
• What are the advantages of flame photometry over standard flame tests?

  • High sensitivity
  • High accuracy
  • High speed
• How is light emitted during flame photometry analyzed?

  It can be separated using a prism into a spectrum.
• What is unique about the emission/absorption spectrum of every element?

  Every element has a unique series of emission/absorption spectrum, similar to a fingerprint.
• How can emission spectra be used in identifying unknown substances?

  • By comparing the emission spectra of unknowns to known spectra
  • Each substance has a unique spectral fingerprint
• What is the Bohr-Rutherford model used for?

  It is used to explain why elements have unique emission spectra.
• What is the challenge associated with the Bohr-Rutherford model?

  To find out why elements have unique emission spectra.
• What colour is seen during a flame test of lithium chloride?

  Crimson red
• What is the trend in reactivity down the group 7 elements?

  Reactivity decreases down the group
• What are the advantages of instrumental methods of analysis?

  • Improved sensitivity
  • Increased accuracy
  • Faster testing speeds
• How can data from a flame photometer be evaluated to determine ion concentration?

  By using a calibration curve
• What is the first step in calibrating a photometer?

  Prepare standard solutions of known concentrations
• What is plotted on a graph during the calibration of a photometer?

  Light intensity readings against known concentrations
• What are the units for light intensity in flame photometry?

  Units of light intensity
• Why is flame photometry considered more useful than standard flame tests?

  It is more sensitive, accurate, and faster
• Describe how a calibration curve is determined.

  Standard solutions are run through the flame photometer and their light intensity values are plotted on a graph.
• What are the key features of flame photometry compared to standard flame tests?

  • More sensitive
  • More accurate
  • Faster results