CH227 Reading Questions
General Chemistry Laboratory
Fall Term 2010
Dr. Deborah Exton

Nov. 1, 2010

Pre-lab reading: Identification of Common Chemicals (Download from Blackboard > Course Information)

Questions:

  1. Silver nitrate will be provided as a testing reagent. Explain what information is obtained from the silver nitrate test.
  2. Name three different physical criteria that would help you identify an unknown liquid.
  3. Explain why potassium permanganate is useful as a testing reagent.
  4. When you go to the laboratory for this experiment, you will be responsible for devising your own experimental protocol. What is the first procedure that you will undertake in the laboratory to begin your chemical investigation?

Oct. 18, 2010

Pre-lab reading: Experiment #4 in the text, "Galvanized Nails, Quality Control, and an Introduction to Green Chemistry" (page 51)
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 and it is not necessary to print out the questions.

Questions:

  1. Explain the purpose of collecting and analyzing class data in addition to your individual data.
  2. What is the most significant personal safety concern associated with this week's lab?
  3. Last week in lab you performed a series of tests to confirm the presence of ions in seawater. For this week, describe a test that you could do that would indicate the presence of hydrogen gas.
  4. Oops! You became distracted in lab and left one of the nails in acid for 20 minutes. Will this have an impact on the results? Explain your answer.

Oct. 4, 2010

Pre-lab reading: "Uncertainty, Error, and Precision", pages 19 - 24 of the lab manual.

Questions:

  1. The mass of an object weighed on an electronic balance in the General Chemistry laboratory was determined to be 19.3200 g. What is the uncertainty in this number?
  2. The student who weighed the previous sample recorded the value in his lab notebook as 19.32 g, rather than 19.3200 g. Was this a correct way to report the mass? Explain your answer.
  3. A coin weighed on an analytical balance was determined to have a mass of 1.9665 g. When the same coin was measured using a "top-loading" balance, the mass was determined to be 1.96 g. Can it be assumed that the mass measured with the first balance was more accurate than the mass measured with the second balance? Clearly explain your answer.
  4. Explain why indeterminate error can never be eliminated from a measurement.