How to time it:

  • You will have 3 weeks of class time.
  • Lab 3 will be open on one weekend.
  • This will not be enough time alone to complete the investigation!
  • You will need at least 4 days to complete the report.

Purpose Statement

  • Needs to investigate variations in the amount of a chemical substance.
  • Must involve the concentration of more than one sample.

Log Book

  • Put everything in your log book.
  • Your log book should record everything to do with your experiment as you do it.
  • Date every entry.
  • It should be in a form that your teacher can read ! (at any point during the investigation)
  • If something is missing from your report but found in your log book, you may get credit for it.
  • Likewise if there is no evidence in your log book of something that you claim to have done in your report, it may be discounted.
  1. Analytical Method Described
  • Is written in own words in enough detail duplication of results.

i.e. there is clear evidence for the provided method being adapted to the specific investigation Safety requirements are noted

  • Method adjusted as a result of trials to ensure appropriate range of data values (greater than 5mL, less than 25mL).

Range should be wide enough and areas suitable, as determined by trials. Modifications are justified

  • Description of method shows clear understanding of overall technique.

General principles are articulated clearly.

  1. Independent Variable
  • Time, location, source, treatment (exposure to heat or light).
  • Cannot simply measure the amount of something.
  • Should include as wide a range as possible.
  • 3 required for achieve
  • 5 or more for merit/excellence
  1. Validity of Results
  • How do you know you’re right?

Do it again.

  • You need triplicate results for each independent variable as a minimum.
  • More will be required if unexpected results occur.
  • One of the independent variable needs to be checked again from scratch.
  • How do you know your standard solutions haven’t changed over the 3 weeks of your experiment?

Test them again!

  • Maybe the concentration of your samples isn’t changing with time – maybe it is the standard that has changed.

How can you be sure?

  • Re-standardise your solution at the end of the experiment.
  1. Data
  • All recorded data must be readily accessible to an independent person so checks can be made on authenticity and processing of data.
  • Solutions must be accurately made up or standardised.
  • Concordant titres must be obtained for averaging (minimum of 3).
  • No room for error in logic process or misinterpretation or application of chemistry involved.
  • Method of processing data can be described in a series of steps or one fully worked example of each type of calculation.
  • Remainder of data can be presented in a table.
  • Level of accuracy in line with requirements for 3.2
  • Quantity is significantly higher than that required for merit (e.g. measuring % alcohol daily during fermentation process rather than 3 or 4 times over a 2-3 week period).
  • For at least 1 independent variable, the entire analytical process must be repeated from scratch to enable conclusion about the validity of the technique to be made.
  1. Significant Figures

Your final result is only as accurate as your least accurate result. Ensure all values are to 3 significant figures. This may mean making up a more concentrated solution and diluting it.

  1. Report
  • Must include the purpose, method and results
  • Includes a summary of relevant data.
  • Where constants (e.g. concentrations of standard solutions) vary between sets of data, this must be clearly indicated.
  • Graphs must be the correct type.


  • Must demonstrate understanding technique and general chemical principles.
  • Comments like “I should have tired harder”, “not enough time are NOT acceptable for excellence.
  • Focusing on trivial sources of error (eye not level with meniscus) is also NOT acceptable for excellence.
  1. Conclusion
  • Your conclusion must relate back to the original purpose.
  • Your research information should be related to your aim, and you discussion of what your results mean should also be related to your aim.
  • Includes a comparison with any values stated my manufacture or compared with typical values quoted in literature.
  • Overall investigation if evaluated with suggestions for improvement, comment on the significance of the investigation.
  1. Bibliography