CH228 Pre-lab Reading Questions
General Chemistry Laboratory
Winter 2011

Jan. 10, 2011

Pre-lab reading: Experiment #8: Spectroscopy (page 71)
Important: At the top of the page, include your name, your TA name, and the date and time of your lab section. Answers may be hand-written.

Questions:

  1. What is meant by the term spectroscopy?
  2. When viewed through a prism or diffraction grating, atomic emission spectra can be seen to be composed of a series of spectral lines.
This question is best answered during the lab lecture:
  1. Describe how, using the data from the Spectroscopy lab, you will be able to determine a value for the Rydberg constant.

Jan. 24, 2011

No reading questions due this week.

Jan. 31, 2011

Pre-lab reading: Experiment #10: Spectrophotometric Determination of a Food-Dye (page 87) and Volume Measurements (page 31) of the text.
Important: At the top of the page, include your name, your TA name, and the date and time of your lab section. Papers without TA names will not be graded. Answers may be hand-written.

Questions:

  1. Explain what is meant by the notations TC and TD on volumetric glassware.
  2. If a volumetric flask is filled beyond the calibration line, the contents must be discarded and you must start the solution preparation over. What is the best way to avoid this situation?
  3. When using a pipet, a small amount of liquid will remain in the tip after draining. You will be using TD pipets in lab this week. Should you force this liquid out of the pipet when transferring solutions?
This question is best answered during the lab lecture:
  1. Explain how the calibration curve will be used to determine the concentration of Allura Red in the unknown sample.

Feb. 7, 2011

Pre-lab reading: The Ideal Gas Law and the Determination of the Gas Constant, R. download from Blackboard, under Course Documents

Questions:

For the Ideal Gas Law experiment, you will generate oxygen gas and record several measurements that will allow you to calculate the value of R, the Ideal Gas Constant.

  1. How will the number of moles of oxygen, n, be determined?
  2. How will the temperature of the oxygen be determined?
  3. How will the volume of the oxygen be determined?
  4. How will the pressure of the oxygen be determined?

Feb. 14, 2011

Pre-lab reading: Experiment #13: A Fatty Acid Monolayer (page 107)

Questions:

  1. When an oil layer on the surface of water is barely visible, the approximate volume of the oil per area is 50 L/km2. What is this value in units of mL/cm2?
  2. What is a fatty acid and what are the properties that make it suitable for forming a monolayer on the surface of water?
This question must be answered during the lab lecture:
  1. Consider the display on the overhead projector. Propose a method that would allow you to determine the number of BBs without requiring you to actually count the BBs. State any additional information that would be required and assumptions that could introduce errors into your calculation.

Feb. 21, 2011

Pre-lab reading: Experiment #14: Forensic Analysis of Ink Using Thin Layer Chromatography (page 113)

Questions:

  1. Is the Thin Layer Chromatography experiment qualitative or quantitative? Explain your answer.
  2. What are the requirements for selection of an appropriate solvent?
  3. Why are samples from a known pen and an unknown pen run on the same TLC plate?
This question will probably be easier to answer during the lab lecture:
  1. The diagram shown below indicates the chromatograms of an impure cholesterol sample (A) and a pure cholesterol sample (B). How would the Rf value for cholesterol change if the TLC was run in a more polar solvent?
    TLC chromatograms